A fuel cell board

Abstract

A fuel cell board 100 has at least one insulating layer 101, 102 and a heat conductive means in or on the insulating layer to direct heat towards or away from a membrane electrode assembly (MEA) 103.

Description

The present disclosure relates to fuel cell boards, fuel cells, uses of fuel cells, A methods of operating a fuel cells and methods of controlling fuel cell temperature. BACKGROUND A fuel cell (e.g. a solid-polymer-electrolyte fuel cell) is an electrochemical device which generates electrical energy and heat from a reactant or oxidant (e.g. pure oxygen or air) and a fuel (e.g. hydrogen or a hydrogen-containing mixture, or a hydrocarbon or hydrocarbon derivative). Fuel cell technology finds application in stationary and mobile applications, such as power stations, vehicles and laptop computers. Typically, a fuel cell comprises two electrodes, an anode and a cathode, separated by an electrolyte membrane that allows ions (e.g. hydrogen ions), but not free electrons, to pass through from one electrode to the other. A catalyst on the electrodes accelerates a reaction with the fuel on the anode to separate electrons and protons / cations, and oxidant on the cathode to undergo a reduction reaction to water. A circuit can then be formed between the anode and the cathode to generate a current to power a load e.g. an electrical device. A reactant fluid, e.g. oxygen or reactant air, is supplied to the cathode and a fuel, e.g. hydrogen, is supplied to the anodes. A single pair of electrodes separated by an electrolyte membrane is called a membrane electrode assembly (MEA). A fuel cell MEA operating under a moderate load produces an output voltage of about 0.7V, which is often too low for many practical considerations. In order to increase this voltage, MEAs are typically assembled into a stack as shown in FIG. 1. Each MEA has a layer of electrolyte membrane la (such as a Nation™ membrane), which comprises an ion-permeable membrane sandwiched between two electrode layers, and an anode 2 and a cathode 3 on either side of the electrolyte membrane. Adjacent MEAs can be separated by an electrically conducting bipolar separator plate 4, and a fuel (e.g. hydrogen) 6 and an oxidant 5 (e.g. oxygen gas or 'reactant air') flow through the channels provided on opposing sides of the bipolar plate. End plates 9 are connected to an external circuit via an electrical connector 7, 8. The number of these MEAs in a stack in a fuel cell determines the total voltage that can be output, and the surface area of each membrane electrode determines the total current that can be drawn / output. Catalyst layers adjacent to the electrodes increase the rate of and efficiency of the reactions at the electrodes. FIG. 2 shows an exemplary fuel cell of the prior art (see e.g. WO 2012 / 117035) in which a plurality of fuel cell boards 22 are stacked between two endplates 21 in order to provide increased voltage and power. Electrode pairs are arranged in a series along either side of a single layer of polymer electrolyte 10, such as a Nafion™ membrane. Anodes 11 are disposed on one surface of these membranes and cathodes 12, separated by gaps are disposed on the other, opposite, surface of these membranes. The anode and cathode respectively of two adjacent electrode pairs may partially overlap. Through-membrane electrical connectors 13 connect the electrodes across the membrane in the overlapping region, and may be produced by a homogeneous chemical deposition process. A catalyst on the electrodes encourages the reactions at the electrodes. A fuel 17, such as hydrogen gas, flows along the face of the fuel cell board 22 supplying the anodes 11 and a reactant or oxidant 16, such as oxygen gas or air, flows along the surface of the fuel cell board 22 supplying the cathodes 12. One electrode at the edge of the upper surface and one electrode at another edge of the lower surface of the fuel cell board are connected to an external circuit via an electrical connection 18, 19. In this series arrangement, the surface area of an electrode pair determines the size of the current for a fuel cell board 22, but the voltage accumulates in proportion to the number of electrode pairs on that fuel cell board 22. Electrically insulating spacers 20 can be integrated into the stack between each of the fuel cell boards each comprising a spacer composed of electrically insulating material (such as plastic). The size of an individual cell (the surface area of a pair of electrodes) determines the size of the current for a fuel cell board. The total number of individual cells on a fuel cell board determines the voltage produced. The number of fuel cell boards in a stack determines the size of the total current of the fuel cell stack. The end cathodes and anodes 11 on each fuel cell board are connected to respective first and second output lines via electrical connections 18, 19. The connection between each fuel cell board in the stack and the second output line can be controlled by a switch mechanism such as a field-effect transistor (FET) switch providing power handling and control directly at the cell. Each of these switches can be controlled by individual control lines. There are a number of factors that determine the performance and consistency of voltage output / current output of a fuel cell. Maintaining the correct water content in the electrolyte membrane is important to optimising and controlling a fuel cell's performance, as the humidity of a fuel cell board can affect performance and control. MEA ion permeable membranes require a certain level of moisture to operate efficiently and to conduct the ionic current efficiently so that the fuel cell current does not drop. Water produced by the cell is removed by the flow of fluid along the cathode or wicked away. If a fuel cell board is too humid or too dry performance can be sub-optimal or variable during operation. Consistency of voltage output / current of a fuel cell is important for most fuel cell applications. Unless specifically desired, too great a voltage variance can affect performance of the operations downstream of the fuel cell. Particularly, temperature of a fuel cell or fuel cell stack, the temperature variance across fuel cells, cells or MEAs or individual fuel cell boards can affect the performance of a fuel cell and consistency of voltage output / current of a fuel cell or subsequent fuel cell stack. If used, heat exchange fluid (e.g. coolant in coolant channels) can affect fuel cell performance and affect the consistency of voltage output / current of a fuel cell. Heat management system in fuel cells constructed of insulator materials, for example printed circuit boards (PCBs), is very important because the internal core of the PCB board is an electrical and heat insulant. Therefore, in order to have efficient heat management and efficient operation, it is desirable that any fuel cell boards are engineered to be able to transfer and dissipate the heat generated by the electrochemical reactions taking place in the board. For example, testing shows that the internal copper surface in contact with the MEA can reach 80-100°C. To avoid overheating and damage of the MEA the heat needs to be removed from the centre of the fuel cell module by dissipating it. Heat exchange fluids in flow channels are the most explored method of controlling the temperature of fuel cells and individual fuel cell boards. A cooling system where a fluid at a temperature lower than the operational temperature of the fuel cell can be used to remove the heat from the fuel cell module and the stack. The greater the AT between the body from which the heat needs to be removed and the cooling fluid, the more efficient the cooling becomes. To maximise this effect it is important to ensure that areas of the fuel cell boards at higher temperatures, nominally heat conductive (e.g. metal) features, are in proximity to regions of the fuel cell at a lower temperature, for example the channels containing the heat exchange fluid or coolant air flows. Fuel cells utilising insulating material boards, such as PCB boards, comprise electrical and heat insulating cores. The thinner the PCB core between the cooling channels and the heat conductive means, the more effective the removal of heat from the fuel cell stack. Coolant e.g. coolant fluid channels may be used in synergy with and / or additionally to the heat removal via conductive means. A fuel cell operates optimally within a certain temperature range. The power performance capability of fuel cells outside such range is negatively affected. It is important to avoid operating fuel cells above or below an ideal operational temperatures range, but it is equally important to be able to manage the temperature of the fuel cell at fuel cell start up. Around freezing temperatures voltage uniformity of the fuel cell boards will deteriorate, due to uneven distribution of reactant gas and localised water and heat generation in the stack. Also, freeze / thaw cycling of fuel cell boards can cause damage to the MEA, specifically the electrolyte. Being able to supply heat to fuel cell boards may improve fuel cell performance and lifetime of the electrolyte. Conventional metal or graphite comprising fuel cells typically utilise a heating element in proximity of the current collectors at the end plates, to warm up the whole stack when the fuel cell starts, relying on the bipolar plates conductivity to spread the heat within the stack. This approach would not work for fuel cells comprising heat insulating materials, such as PCBs. In view of the foregoing, there is a need to improve control of the temperature of a fuel cell through new methods and novel fuel cell designs. It is also desirable to be able to implement a heat management strategy during operation of fuel cells to ensure different areas of the stack requiring different amount of heat to be provided to, or to be removed from, are catered accordingly. Means to control the temperature of fuel cell boards are needed, for example to remove heat or to add heat to the fuel cell where the electrochemical reaction is taking place, respectively in operation and in cold mode. It is desirable to provide improved fuel cells, uses of fuel cells, methods of controlling fuel cell temperature, components for fuel cells. SUMMARY A first aspect of preferred embodiments provides a fuel cell board comprising at least one insulating layer, at least membrane electrode assembly (MEA), the MEA comprising an ion permeable membrane and at least one anode and at least one cathode. Each or all cathodes are arranged across a first surface of the ion permeable membrane and each or all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane. The fuel cell board comprises heat conductive means in or on the insulating layer to direct heat towards or away from the MEA. The insulating layer may be electrically and / or thermally insulating. The heat conductive means in or on the insulating layer to direct heat towards or away from the MEA may be a solid heat transfer means. These means may be thermally connected or coupled to further heat transfer means, for example a heat sink, further solid heat transfer means, a thermal management fluid (e.g. a coolant). Heat may be dissipated or transferred externally to the fuel cell. The present invention addresses heat management of fuel cell stacks made of insulating materials, such as PCBs. It utilises heat transfer means, for example solid heat transfer means such as heat traces, thermally conductive vias or conductive material plating to transfer heat within a fuel cell stack. Depending on the means employed, or where they are employed, heat could be transferred towards or away from the fuel cell board and / or towards or away from the MEA. These means enable the effective heat removal from fuel cell by working in conjunction with other heat exchange systems, such as air or liquid coolant by overcoming the thermal insulating nature of the plates. These means can be to heat or cool, i.e. transfer heat to or away from, fuel cell boards or MEAs. Thus, these can be utilised to manage the temperature of the fuel cell stacks at start up (heating) or during operation (typically cooling, but also possibly heating). They may be used separately to or in conjunction with liquid or air coolant systems, as described herein. They may be utilised in different environmental conditions, i.e. heating may be utilised more in cooler environments. These means allow control of the temperature of a fuel cell, and consequentially the humidity of the fuel cell more locally than in a regular fuel cell made with bipolar plates of metal and / or graphite. These fuel cells being made of insulating materials, such as PCBs, allow for a tailored localised heat management, contrasted with metal and / or graphite bipolar cell, as mentioned earlier. In fuel cells which utilise bipolar plates the plates themselves are conductive, being made of metal and or graphite, therefore the conduction of heat and current is indiscriminate. Insulating materials prevent indiscriminate conduction of electricity and heat, allowing more accurate targeting of the heat removal and heat delivery when and where it is needed in a fuel cell stack. This is possible due to the insulating materials used to form the fuel cell boards of the present invention, and would not be applied to conventional graphite and metal fuel cells, as it would not work correctly. In fuel cell boards made of non-conductive material, the conduction of heat and current can be directional and preferential paths can be engineered, using heat conductive means, or conductive features. Heat management in air-cooled and liquid cooled systems using heat transfer means, or conductive features, to manage the temperature and by proxy the humidity within the fuel cell stack by removing heat from part of the fuel cell module and / or the fuel cell stack experiencing higher temperature than the rest of the module and / or stack and alternatively providing additional heat to the stack in operational conditions where the temperature of the fuel cell is too low to produce a uniform current generation to reach optimal performance of the fuel cell module and the homogeneous performance of the fuel cell stack. The ability to target heat removal and heat delivery when and where it is needed in a fuel cell stack includes being able to asymmetrically provide or remove heat throughout a fuel cell stack, allowing for dynamic monitoring and alteration during fuel cell operation. This represents an improvement on previous PCB-based fuel cell technologies, as those do not explore utilising heat conductive means to transfer heat to or from fuel cell boards, and certainly not the improvements demonstrated herein. The heat conductive means may comprise means to conduct heat parallel to the MEA along the fuel cell board, horizontally along at least part of the at least one insulating layer. Preferably, the heat conductive means comprises conductive material located on a surface of the at least one insulating layer, this surface of the at least one insulating layer facing the MEA of the fuel cell board, wherein the conductive material located on a surface of the at least one insulating layer is connected (i.e. connected thermally so that heat can transfer) to heat conductive vias, provided orthogonal to the MEA through at least part of the at least one insulating layer. The conductive material and heat conductive vias are capable of transferring thermal energy away from the MEA. The vias may be through the insulating layer or through the whole fuel cell board. Or they may only be partially through the insulating layer or the fuel cell board. Or they may be buried in the fuel cell board. Preferably, the insulating layer comprises a further conductive material located on the opposite surface of the at least one insulating layer to the surface of the at least one insulating layer facing the MEA of the fuel cell board. Heat conductive vias can be used to move heat from one area of the fuel cell to another, such as from the conductive material located on a surface near or in contact with the MEA to an external surface of the insulating material or fuel cell board, in proximity to a means to cool the fuel cell board (such as a coolant channel), or a further heat transfer means, to take the heat to, for example a heat sink. These establish a low thermal resistance path from the internal surface of the insulating layers / fuel cell board, adjacent to the MEA to the external surface of the fuel cell board. They act as a highly thermal conductive bridge to permit a considerable amount of heat flux to flow from the membrane electrode assembly to an external environment. Using these means in combination with other heat exchange means, as described herein, allows the creation of a three-dimensional heat exchange architecture to control the temperature of a fuel cell. The fuel cell boards described herein are structures comprising at least one insulant core sandwiched between at least one, possibly two conductive surfaces, for example a metal, for example copper. So that a core of insulating material is sandwiched or layered between conductive material. Multiple conductive features, surfaces or other can be present between the two outer conductive surfaces. This means the outer surfaces of the insulating layers will at least partially be able to conduct heat (and electricity) towards or away from the MEA and fuel cell board, depending on the design. Preferably, the heat conductive means transfers heat to a means to absorb or dissipate heat. The means to absorb or dissipate heat may be a thermal management fluid, coolant fluid, heat sink, a vent to outside the fuel cell, a heat spreader, a heat pipe, another fuel cell board in the fuel cell, a vent or an opening in the fuel cell housing, or any combination thereof. Preferably, the heat conductive vias are selected from the group consisting of through holes, buried vias, blind vias or any combination of these, optionally wherein the holes or vias are plated or filled with a conductive material. Preferably, the heat conductive vias have a diameter of 100pm to 5mm, preferably between 125 pm and 2mm, preferably between 150 pm and 1mm, preferably between 200 pm and 700 pm, preferably around 300 pm. Preferably, the heat conductive vias have a diameter of at least 150 pm. Preferably, the heat conductive vias have a diameter less than 3mm. Preferably, more heat conductive vias are located in one or more of the following: i) areas of the fuel cell board which experience a higher temperature in fuel cell operation than those areas of the fuel cell board which experience a lower temperature in operation; ii) areas of the fuel cell board which require cooling; iii) areas of the fuel cell board experiencing a greater exotherm from the electrochemical reaction in operation; iv) sections of the flow-field where at least one of the reactant-flows is hotter; v) in areas where anode and cathode flow fields are adjacent or closer to each other or cross over; v) areas of the fuel cell board with a lower water concentration. Preferably, the density of heat conductive vias is preferably between 5 PTH per cm2 and 20 PTH per cm2, preferably between 7 PTH per cm2 and 18 PTH per cm2, preferably between 9 PTH per cm2 and 15 PTH per cm2, preferably about 11 PTH per cm2. Preferably, the heat conductive means is one or more means to direct heat towards the MEA. The heat conductive means comprise one or more heat traces to conduct heat parallel to the MEA along the fuel cell board. The heat traces may be capable of transferring thermal energy to the MEA. These means can be used to transfer heat to the fuel cell board and MEA to raise the temperature of the board, for example as part of a cold start operation of the fuel cell. These conductive means are separated from the main electrical conduction means in the fuel cell board, so that they are solely used for heat conduction and so as to not be affected directly by fuel cell operation. So when a fuel cell stack is in operation, because the heat transfer means are separated from the electrically conducting means, due to the insulating nature of the insulating layers utilised, it is possible to use these means to independently raise the temperature of fuel cell boards which might be operating at a lower temperature than the rest of the fuel cell boards, which might increase operational efficiency of these boards and thus the whole stack overall. Preferably, the one or more heat traces are located inside or on the first insulating layer, and / or wherein the one or more heat traces are located inside or on a further insulating layer, and / or wherein the one or more heat traces are located between the first insulating layer and a further Insulating layer, and / or wherein the one or more heat traces are located between two or more further insulating layers. The heat traces of adjacent fuel cell boards may be connected to one another. Heat traces may be connected in series or connected in parallel. The heat traces may also be individually switchable. Preferably, the one or more heat traces are connected to one or more means to conduct heat from the at least one insulating layer to a further insulating layer. The means to conduct heat from the at least one insulating layer to a further insulating layer may comprise one or more of heat conductive through vias or an edge of plate connection to a further insulating layer. The heat conductive through vias are, provided orthogonal to the MEA through the at least one insulating layer and / or through one or more of the further insulating layers, wherein the conductive material and through vias are for transferring thermal energy to the heat traces, wherein the heat conductive vias connected to the heat traces do not conduct electrical current away from or towards the MEA. The edge of plate connection to a further insulating layer comprises a plating of metallic material around the end of the first insulating layers. The vias may be through the whole fuel cell board. The conductive through vias connected to the heat traces may be separate to or a different via system to the heat conductive vias provided for transferring thermal and electrical energy away from the MEA. The heat conductive through vias are not connected to the conductive material on the surface of the at least one insulating layer facing the MEA of the fuel cell board because they are not connected to the MEA or any conductive material adjacent to the MEA. Preferably, the heat traces are tracks of heat conductive material. Preferably, the heat conductive means is connected to a means to transfer heat or energy capable of generating heat to the fuel cell board Preferably, the means to transfer heat to the fuel cell board is a source of electrical energy Preferably, this is a battery, or the fuel cell itself. Preferably, the heat conductive means, means to conduct heat parallel to the MEA along the fuel cell board and / or the heat conductive vias comprise a conductive material. Preferably, the conductive material is a metal. Preferably, the conductive material is copper, nickel, a copper alloy, a nickel alloy, graphite or an ink. Preferably they are filled with a conductive material such as carbon, resin, metal or a conductive polymer. In order to maximise a fuel cell's power-density, it is possible to have the heat conductive means on the same plane as the outer conductive surface of a fuel cell board, a surface used to transfer electricity through the stack as part of the main circuit, as a track insulated from such surface, so that the two conductive means do not come into contact. This requires careful design of both conductive features, both the track and the surface, for the two separated circuits ensuring robust separation. However, fuel cell environments inherently contain some humidity and water. This can act to crystallise as particles of ice and melt when the cell is powered, for example during the cold start. Therefore if the separation is not sufficiently robust, for example when the channel is thinner than the diameter of a water droplet, such water can bridge the two circuits causing possible shorting of the fuel cell board. Embedding the horizontal means, preferably the heat trace, inside an insulating layer or capping inside a further insulating layer will robustly separate the heat transfer means from the main electrical circuit means. This further reduces any possibility of electrical shorting in the fuel cell module. This further insulating layer may be thinner than the other layer so as to minimise the size of the fuel cell board, increasing fuel cell stack density. Preferably, the fuel cell board comprises a further or second insulating layer. Preferably this comprises electrically conductive through vias to conduct electrical current from the anodes through the first of the insulating layers. The first insulating layer is adjacent the anode side of the MEA. The fuel cell board comprises electrically conductive through vias to conduct electrical current to the cathodes through the second of the at least two insulating layers, wherein the second insulating layer is adjacent the cathode side of the MEA. Or, preferably the first insulating layer, the second insulating layer and the MEA comprise electrically conductive through all three, connecting one face of the fuel cell board to another face of the fuel cell board. These would electrically connect the first insulating layer to the second insulting layer. Preferably, the heat conductive vias are selected from the group consisting of through holes, buried vias, blind vias, or any combination of these, optionally wherein the holes or vias are plated or filled with a conductive material. Preferably, the heat conductive means, means to conduct heat parallel to the MEA along the fuel cell board and / or the heat conductive vias comprise a conductive material. Preferably, the conductive material is a metal. Preferably, the conductive material is copper, nickel, a copper alloy, a nickel alloy, graphite or an ink. Preferably they are filled with a conductive material such as carbon, resin, metal or a conductive polymer. Preferably, the at least one insulating layer is a printed circuit board (PCB), Preferably, any other insulating layers in the fuel cell board are also PCBs. Preferably, the MEA comprises at least one gas diffusion layer (GDL) and / or a catalyst. A further aspect of preferred embodiments provides a fuel cell comprising at least one fuel cell board of any of the fuel cell boards of the first aspect, or any fuel cell board as described herein. Preferably, the fuel cell comprises one or more further fuel cell boards of the fuel cell boards of the first aspect, or any fuel cell board as described herein. Preferably the heat conductive means is different in at least two of the fuel cell boards. Preferably, one or more of the fuel cell boards closer to the end plates or closer to the peripheral point(s) of the fuel cell stack or further away from the central fuel cell board or further away from the central point of the fuel cell stack comprise heat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards. Preferably, the two fuel cell boards at the top and bottom of the fuel cell stack or adjacent the fuel cell end plates comprise heat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards. Preferably, one or more of the more central fuel cell boards or those fuel cell boards further away from the fuel cell end plates or the peripheral point(s) of the fuel cell comprise increased heat conductive means in or on the insulating layer(s) to direct heat away from the MEA compared to the other fuel cell boards. The presently described inventions are of a modular nature, where fuel cell boards can be stacked with means to cool the boards and / or means to provide the reactants to the fuel cell boards. The modular nature allows an increased control over the design of the fuel cell stacks, allowing for easy customisation in size, shape, power and voltage-current characteristics of the fuel cells. Individual boards can be individually switchable or removable, causing a change in capacity. Fuel cells of varying design can easily be manufactured from the same components. PCB technology has the advantage of enabling the elements to be manufactured in large quantities and at low cost. For example, multiple flow field boards can be manufactured at the same time, by using thin laminate boards which are stacked and then simultaneously routed or drilled. Individually routed boards are then stacked and laminated together. PCBs have a high mechanical strength, whilst being light, and when laminated together provide a solid structure, with good contact between the individual layers. Accordingly, a monolithic, light, and completely sealed structure is produced. Use of PCBs also enables the present fuel cells, fuel cell boards and components to be constructed without a mass or size penalty which may be present using other materials such as metal. These can be easily plated with copper and / or have vias or other means to conduct electrical current through the plates. This allows improved control of current through stacks, as not all of the plates, spacers etc need be conductive, like when prior art bipolar plates or conductive metal components are utilised in prior art stacks. Different areas of the stack may be engineered (different thickness of the conductive material, e.g. copper thickness) to receive a greater amount of heat; for example area of the fuel cell stack which may often be colder than the rest of the stack, for example peripheral modules in proximity of the end plates. Preferably, each fuel cell board in the fuel cell is arranged such that the cathodes of each fuel cell board face the anodes of the adjacent fuel cell board and wherein each fuel cell board is arranged such that the anodes of each fuel cell board face the cathodes of the adjacent fuel cell board. Preferably, each fuel cell board in the fuel cell is arranged such that the cathodes of each fuel cell board face the cathodes of the adjacent fuel cell board and wherein each fuel cell board is arranged such that the anodes of each fuel cell board face the anodes of the adjacent fuel cell board. Preferably, the Membrane Electrode Assembly (MEA) further comprises at least one gas diffusion layer. The one or more gas diffusion layer(s) may be between the at least one cathode or all of the cathodes and the first insulating layer and at least one or all of the first fluid path(s). The one or more gas diffusion layer(s) may be between the at least one anode or all of the anodes and the second insulating layer and at least one or all of the second fluid path(s). The MEA may comprise multiple gas diffusion layers as described herein. Preferably, the fuel cell comprises a means to air cool at least one of the fuel cell boards. Preferably, each fuel cell board may have a power rating of at least 10W. Preferably, each fuel cell board may have a power rating of up to 1000W. Preferably, each fuel cell board may have a power rating of 10W to 1000W. Preferably, a fuel cell comprising multiple fuel cell boards may have a power rating of at least 20W. Preferably, each fuel cell comprising multiple fuel cell boards may have a power rating of up to lOOOkW. Preferably, each fuel cell comprising multiple fuel cell boards may have a power rating of 20W to lOOOkW. Preferably, one or more of the layers described herein are laminated together. This lamination may be achieved by chemical bonding by heating layers of prepreg between the insulating layers under pressure and an increased temperature, as described herein. Use of an epoxy resin prepreg also maintains compression of the gas diffusion layer of the MEAs, a critical component in maintaining fuel cell performance as it provides a sufficiently low resistance electrical path without compromising distribution of reactant fluids. Preferably, the fuel cell board comprises means configured to supply the cathodes with an oxidant fluid and the fuel cell board comprises means configured to supply the anodes with a reductant fluid. Preferably, the means to supply the cathodes with an oxidant fluid is an insulating layer comprising at least one first fluid path, and / or wherein the means configured to supply the anodes with a reductant fluid is an insulating layer comprising at least one first fluid path. Preferably, the at least one first insulating layer comprises at least one first fluid path and is either the means configured to supply the cathodes with an oxidant fluid or is the means configured to supply the anodes with a reductant fluid. One of these insulating layers will be the 'first insulating layer' described earlier. Preferably, the oxidant fluid described in any aspect of the invention described herein is air and the reductant fluid is hydrogen gas. Preferably, the first or second insulating layer comprises at least one fluid path for a heat exchange fluid. Preferably, a second insulating layer of the fuel cell board further comprises the at least one further or a third fluid path for a heat exchange fluid. The at least one further / third fluid path is arranged so that the heat exchange fluid can control the thermal properties or control the temperature of the fuel cell board, preferably at least the thermal properties or the temperature of the at least one anode. The heat exchange fluid is separated from the oxidant fluid, these are different fluid flows. Preferably, the at least one further / third fluid path is on the opposite face of the insulating layer to the at least one first fluid path or the at least one second fluid path. Preferably, the oxidant fluid, the reductant fluid and / or the one or more heat exchange fluids enter and leave the relevant fluid paths described herein via inlets and outlets. These inlets and outlets may connect the fluid paths to manifolds which supply the relevant fluids to the fluid paths. These manifolds are those described herein, but may be apertures in the insulating layers. Preferably, the at least one ion permeable membrane is bonded to the at least one insulating layer. Preferably, the one or more insulating layers are PCB boards. The insulating layers of the embodiments herein can be printed circuit board (PCB) layers, as described herein. Boards of insulating materials, such as FR.-4 epoxy resin boards, have the advantage of enabling the elements to be manufactured in large quantities and at low cost. For example, multiple flow field boards can be manufactured at the same time, by using thin laminate boards which are stacked and then simultaneously routed or drilled. Individually routed boards are then stacked and laminated together. PCBs have a high mechanical strength, whilst being light, and when laminated together provide a solid structure, with good contact between the individual layers. Accordingly, a monolithic, light, and completely sealed structure is produced. Use of insulating materials to construct such fuel cell also enables the present fuel cells, fuel cell boards and components to be constructed without a mass or size penalty which may be present using other materials such as metal. These insulating material plates can be plated with conductive material and / or have vias or other means to conduct electrical current and / or heat through or across the plates. This allows improved control of current and temperature through stacks, as not all of the plates, spacers etc need be electrically or heat conductive, like when prior art bipolar plates or conductive metal components are utilised in prior art stacks. The fuel cell boards as disclosed herein may comprise single or multiple anodes and single or multiple cathodes. All cathodes are arranged across a first surface of the ion permeable membrane and all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane. The anodes and cathodes of the fuel cells or fuel cell boards described herein may be described as or referred to "segmented" throughout. Segmented anodes or cathodes are those with a gap between adjacent anodes or cathodes. Segmented anodes and cathodes form segmented membrane electrode assemblies (MEAs) or 'cells'. Each MEA can be formed of one anode and one cathode, each on an opposing face of an ion permeable membrane. One ion permeable membrane can have multiple anodes or cathodes or multiple MEAs across its surface(s). Multiple segmented MEAs can be found on a single fuel cell board of the present invention. MEAs may also be referred to as 'cells' herein. There may be multiple ion permeable membranes across a fuel cell board, each with one or more anodes or cathodes. Each MEA may be one anode, one cathode and one ion permeable membrane. These are arranged such that each anode overlaps with at least one cathode through the ion permeable membrane and / or such that each cathode overlaps with at least one anode through an ion permeable membrane. The anodes and the cathodes have a gap between the adjacent anodes or cathodes on the same fuel cell board. Variation in the conditions fuel cell boards are subject to, for example variance in temperature, humidity and fuel concentration, as described in greater detail herein, can be accounted for by varying the properties of the individual cells individually. These variances will result in a variation in current density across fuel cell boards. Design can account for variation across a fuel cell board which can occur depending on the fuel flow paths across boards. Tailoring heat or temperature control for different fuel cell boards to account for variance in conditions boards are subject to will result in a reduction in potential variance across the board. A reduction in potential variance across the board may be referred to as a flattening of the voltage (i.e. keeping the voltage within a certain range a reduction in potential variance across the board). A reduction in potential variance of fuel cell boards through a stack is also desirable. Reduction in the potential variance across the board results in improved performance of the fuel cell boards, and increased fuel cell board efficiency. The fuel cells and fuel cell boards described herein can be tailored to give the same power output but at a different voltage. This is uniquely possible with the insulating material (e.g. PCB) fuel cell boards as described herein, because of their heat and electrical insulating properties and because of how they can be manufactured, when compared to for example metal or graphite fuel cell boards. Because PCBs are insulating material, unlike metal or graphite based fuel cell boards of the prior art where the whole board is conductive, the fuel cell boards described herein can be designed to ensure that current only passes in specific locations, for example plated holes, use of conductive material (e.g. copper) plating in selective areas of the PCB board, or electrical connection tabs at the edges of the MEAs. These may be connected so that the connections can dynamically be varied to maintain a desired voltage range (whilst keeping the KW power output constant), providing a consistent output if desired. This is not technically possible in, for example, metal fuel cell boards. The designs described herein reduces boards of the fuel cell stack ending up at a relatively low potential during operation. This is beneficial because large variance in potential can accelerate degradation of fuel cell boards. Thus, the fuel cell boards described herein have improved degradation resistance / longer lifespans. Improved heat management will also improve the lifespan of the fuel cell, particularly the fuel cell boards, particularly the MEA. The careful design of the heat transfer means as described herein, e.g. to remove excess heat from the MEA, reduces parts of the fuel cell ending up at a relatively low potential during operation, or constant temperature cycling which can damage the MEA. A fuel cell of any aspect disclosed herein may comprise at least one fuel cell board, particularly a fuel cell board of the first aspect of the invention. Each fuel cell board comprises at least one first insulating layer, at least one ion permeable membrane, and at least one or multiple anodes and at least one or multiple cathodes. All cathodes are arranged across a first surface of the ion permeable membrane and all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane. These are arranged such that each anode overlaps with at least one cathode through the ion permeable membrane and / or such that each cathode overlaps with at least one anode through the ion permeable membrane. If more than one of each, pairs of anodes and cathodes across the at least one ion permeable membrane are electrically connected in parallel with adjacent pairs of pairs of anodes and cathodes. Individual cells comprise at least one anode and at least one cathode on opposite faces of at least one ion permeable membrane such that the anode and cathode can exchange ions across the at least one ion permeable membrane. Each individual cell is connected in parallel across the fuel cell board. Preferably, an oxidant fluid is initially supplied to the cathodes of the fuel cell board in a direction substantially opposite to direction in which a reductant fluid is initially supplied to the anodes of the fuel cell board. Preferably, any heat exchange fluid supplied to the board is initially supplied to the fuel cell board either in a direction substantially similar to the direction in which a reductant fluid is initially supplied (to the anodes) of the fuel cell board or in a direction substantially similar to the direction in which an oxidant fluid is initially supplied (to the cathodes) of the fuel cell board. Preferably there may be 2, 3, 4, 5, 6, 7, 8, 9, 10 or over 10 MEAs on a single fuel cell board. Preferably there may be 20, 30, 40, 50, 60, 70, 80, 90, 100 or over 100 MEAs on a single fuel cell board. Preferably, fuel cell boards comprise means to conduct electrical current from one face of the fuel cell board to the other face of the fuel cell board. Preferably, these means are plated holes. These plated holes may be plated through holes. These holes may go through the whole fuel cell board and can carry electrical current in series across a fuel cell board. Preferably, the means may conduct electrical current to or from copper plating on the insulating layer. Preferably, the means may also comprise blind and / or buried vias. Preferably, the fuel cell board comprises means to conduct electrical current from the anodes through the at least one insulating layer to the surface of the at least one first insulating layer, and the fuel cell board comprises means to conduct electrical current to the cathodes through the at least second insulating layer from the surface of the at least one second insulating layer. Preferably, these means are plated holes. These plated holes may be plated through holes. Preferably, the number or frequency of the means to conduct electrical current vary across the fuel cell board. These can vary to account for variance in the anode and / or cathode design across the fuel cell board. A higher number, concentration or density of these can relate to a higher current density across a fuel cell board. Preferably, the means may conduct electrical current to or from copper plating on the insulating layer. Preferably, each anode may overlap with at least one cathode through the ion permeable membrane and / or each cathode may overlaps with at least one anode through the ion permeable membrane. Overlaps refers to the body of the anode or cathode on one face of the ion permeable membrane at least in part overlapping with the body of the anode or cathode on the other face of the ion permeable membrane. Preferably, the first insulating layer comprises at least one first fluid path. Preferably, the first insulating layer comprises multiple first fluid paths. Preferably, the multiple first fluid paths are substantially parallel to each other. Preferably, the fuel cell board comprises a second insulating layer. The first insulating layer may comprise at least one first fluid path, the second insulating layer may comprise at least one second fluid path. The at least one ion permeable membrane and the multiple anodes and the multiple cathodes may be located between the first insulating layer and the second insulating layer so that the at least one first fluid path is arranged such that an oxidant fluid can be supplied to one or more of the cathodes (all of the cathodes) of the at least one fuel cell board and so that the at least one second fluid path is arranged such that a reductant fluid can be supplied to one or more of the anodes (all of the anodes) of the at least one fuel cell board. The MEA, the first insulating layer and the second insulating layer may be laminated together to form the fuel cell board. Preferably, at least two of the layers of the fuel cell board are laminated together. Preferably, the first insulating layer comprises multiple first fluid paths. Preferably, the multiple first fluid paths are substantially parallel to each other. Preferably, the second insulating layer comprises multiple second fluid paths, Preferably, the multiple second fluid paths are substantially parallel to each other. Preferably, at least one of the at least one first fluid paths has a different flow path pathway / design to the at least one second fluid path. Preferably, the fuel cell comprises a plurality of fuel cell boards, of any fuel cell board described herein. The fuel cell boards may be arranged such that the first insulating layer and the one or more cathodes of each fuel cell board face the second insulating layer and the one or more anodes of an adjacent fuel cell board. The at least fuel cell board may be arranged such that the second insulating layer and the one or more anodes of each fuel cell board face the first insulating layer and the one or more cathodes of an adjacent fuel cell board. Preferably, at least one of the first fluid path, the second fluid path or the third / further fluid path is substantially linear. Preferably, at least one of the first fluid path, the second fluid path or the third / further fluid path is serpentine. Preferably, the fuel cell board comprises multiple first fluid paths and / or multiple second fluid paths and / or multiple third / further fluid paths. Preferably, the fuel cell board comprising at least one of the following: multiple first fluid paths which are substantially linear and substantially parallel with each other, multiple second fluid paths which are substantially linear and substantially parallel with each other and / or multiple third / further fluid paths which are substantially linear and substantially parallel with each other. Preferably, the at least one further / third fluid path has a different flow path to the at least one first fluid path or the at least one second fluid path. For example, one of the paths may be substantially linear and the other may be serpentine. Preferably there are more of one of the multiple first fluid paths and / or multiple second fluid paths and / or multiple third / further fluid paths than the other fluid paths, for example there may be more third / further fluid paths than the first fluid paths. Preferably, the fuel cell further comprises further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards. The means to control the temperature of the at least one fuel cell board comprises at least one further insulating layer, the further insulating layer comprising at least one further / fourth fluid path for a heat exchange fluid. This at least one further insulating layer is arranged between the first insulating layer of the fuel cell board and the second insulating layer of an adjacent fuel cell board. This at least one further insulating layer comprises means to conduct electrical current from one face of the at least one further insulating layer to the other face of the at least one further insulating layer. This may allow it to act as a bipolar plate. This may enable electrical contact of anodes and cathodes of adjacent fuel cell boards, as described herein. The heat exchange insulating layer may be laminated to the first or the second insulating layer of the fuel cell board. Preferably, this further means laminated to the second insulating layer, i.e. adjacent to the anode side of the MEA. Lamination of the further means to the fuel cell board allows increased energy density because in this further means there may be just one further layer, as opposed to multiple layer means or thicker means as described previously. Further, sealing the further means plate to the fuel cell board simplifies assembly of the fuel cell stacks, due to there being fewer components and fewer non-built-in seals to the stack. Preferably, this further / fourth fluid path carries a coolant fluid to cool the fuel cell board or an adjacent fuel cell board. Preferably this heat exchange fluid is the same as the heat exchange fluid in the third / further fluid path located in / on the first insulating layer and / or located in / on the second insulating layer. Preferably this heat exchange fluid is different to the heat exchange fluid in the third / further fluid path located in / on the first insulating layer and / or located in / on the second insulating layer. This further means to control the temperature of the at least one fuel cell board or adjacent fuel cell board may be present when neither of the at least one of the first insulating layer or the second insulating layer comprises at least one further / third fluid path for a heat exchange fluid (i.e. in the absence of the at least one further / third fluid path for a heat exchange fluid). Preferably the further means to control the temperature of the at least one fuel cell board comprises a second further insulating layer, wherein the second layer seals or caps the flow path of the further / fourth fluid path (acting as described for other embodiments herein). The first insulating layer of this further comprises further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards may be thicker than the second further insulating layer, or the second further insulating layer may be thinner than the first insulating layer of this further comprises further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards. This further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards may have multiple fluid paths for heat exchange fluid, of different sizes, shapes and / or dimensions, different fluid types, or fluids at different flow rates or different fluid temperatures. Fluids could be at different temperatures or different flow rates in different plates, or at different temperatures or at different flow rates in different flow paths within the same plate. This can address varying coolant need throughout a fuel cell. Preferably, where multiple further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards are present in a single fuel cell stack, each further means to control the temperature of the at least one fuel cell board or adjacent fuel cell boards may have different fluid paths, different sized, shaped or dimensioned fluid paths or be designed to carry different fluids, or different temperature fluids, or fluids with different flow rates. This can address varying coolant need throughout a fuel cell. The further / fourth fluid path can be routed or depth routed into the insulating layer of this plate. Preferably, the face or surface of the first insulating layer adjacent to the cathodes in the fuel cell board is the face or surface which comprises the at least one first fluid flow path or channel, so that oxidant fluid can flow to or diffuse to the one or more of the cathodes of the MEA (all of the cathodes). This may be through a gas diffusion layer. Preferably, the face or surface of the second insulating layer adjacent to the anodes in the fuel cell board is the face or surface which comprises the at least one second fluid flow path or channel, so that reductant fluid can flow to or diffuse to the one or more of the anodes of the MEA (all of the anodes). This may be through a gas diffusion layer. Preferably, a fuel cell may comprise one or more spacers between one or more fuel cell boards. Preferably, the spacers have a means to conduct electrical current from one face of the spacer to the other face. Preferably, the means to conduct electrical current can be substantially at only one end of the spacer. This allows the design and creation of conductive paths up / down a fuel cell stack. Fuel cell boards in a stack can be put in series or parallel depending on how these are configured. Preferably, at least one of the spacers is an anode spacer, comprising at least one insulating layer and is a means to cool at least one fuel cell board. The anode spacer is located between the second insulating layers of the adjacent fuel cell boards. The anode spacer comprises at least one third fluid path arranged to carry coolant fluid. Here, the coolant fluid is air and wherein the fluid flow path is from the atmosphere outside of the fuel cell to the further fluid path arranged to carry coolant fluid. Preferably, at least one of the spacers is a cathode spacer and comprises at least one insulating layer. The cathode spacer is located between the first insulating layers of the adjacent fuel cell boards. The anode spacer comprises at least one further fluid path arranged to supply an oxidant fluid to the at least one first fluid path. Here, the oxidant fluid is air and wherein there is a direct fluid flow path from the atmosphere outside of the fuel cell to the further fluid path arranged to supply an oxidant fluid to the at least one first fluid path. An 'anode spacer' can be used to give a gap where coolant air from the atmosphere can be supplied. A 'cathode spacer' can be used to give a gap where reactant air from the atmosphere can be supplied. Spacers may be configured with an integrated coolant conduit defining fluid paths. They can be integrated reactant conduits defining at least one fluid paths for supplying a reactant fluid to the at least one fuel cell board, cathodes or anodes. Spacers may be configured without integrated conduits, but so that fluid flow is directed in the desired direction, for example by having entry and exit points so that pressurised air enters or leaves the spacers in the desired directions (e.g. perpendicular to entry). Spacers can have fluid entry and / or exit points to direct the fluid paths. Spacers could have multiple different fluid paths, of different sizes, shapes and / or dimensions or different coolant types. Fluids could be at different flow rates or different fluid temperatures in different spacers, or at different flow rates or temperatures in different flow paths within the same spacer. This can address varying coolant or reactant need throughout a fuel cell. Preferably, when multiple spacers are present in a fuel cell stack, each spacer may have different fluid paths, different sized, shaped or dimensioned fluid paths or be designed to carry different fluids, or they may have fluids at different flow rates or different fluid temperatures. Multiple anode or multiple cathode spacers could be different from each other, as well as anode and cathode spacers being different from each other. This can address varying coolant or reactant need throughout a fuel cell. In these designs it is not necessary to stack the anode of one fuel cell board next to the cathode of the next, adjacent fuel cell boards may have their anode sides (or cathode sides) facing each other, in which case spacers can be provided as there is no risk of the gases mixing. This results in a significant increase in packing density of the fuel cell as one gas flow can serve two fuel cell boards, reducing the number of seals, and increasing the power density. Repeat distances (i.e. the thickness of the combined fuel cell board and feed region) may be as low as about 0.2 mm. Hence a far higher volumetric power density of the fuel cell system is achievable. Further, the channels in the surface are easily formed for gas circulation and internal conduits are easily integrated into the spacer, allowing coolant and / or water to circulate and providing a cooling and water distribution system for the stack. Channels provided for the reactant gases and channels or conduits associated with the cooling and / or water distribution system are separate as discussed in more detail below. Preferably, the fuel cell comprises multiple fuel cell boards, multiple anode spacers and multiple cathode spacers. The fuel cell may comprise a single fuel cell board or a plurality of fuel cell boards. In some embodiments, the or each fuel cell board may comprise a plurality of anodes and a plurality of cathodes arranged in pairs, and a plurality of electrical connectors configured to connect adjacent pairs of anodes and cathodes through the at least one ion permeable membrane. By providing a fuel cell board with a plurality of anode-cathode pairs, the total output voltage of the fuel cell board is increased. Preferably, the first insulating layer comprises multiple first fluid paths to supply the oxidant fluid to the cathodes at multiple points across each or all cathodes of a single MEA. The multiple first fluid paths are channels or holes through the body of the first insulating layer. The parts of the first insulating layer with channels or holes not formed in the insulating layer are in contact with the cathodes to provide an electrically conductive path from the cathode through the first insulating material layer. Here, the oxidant fluid is air and wherein there is a fluid flow path from the atmosphere outside of the fuel cell to the further fluid paths arranged to supply air to the multiple first fluid paths. Preferably, at least 40% of surface area of the first insulating layer comprises channels or holes or wherein the ratio of surface area of the first insulating layer comprising channels or holes to surface area of the first insulating layer not comprising channels or holes is 60:40, and / or wherein there are at least 100 channels or holes in the first insulating layer to provide the fluid paths. The multiple fluid paths can be in the form of multiple holes through the whole body of the plate to form the multiple first fluid paths to direct the oxidant fluid to the cathodes at multiple points across each or all cathodes. The nature of the structure of the plate is so that the cathode(s) are exposed to the oxidant fluid at multiple points and to ensure high level of reactivity. Open space above a cathode ('fluid path' or 'channel') serves to deliver reactant air and any unexposed space (referred to as a land herein) is making electrical contact to the cathode, to provide a conductive path. Holes are highly manufacturable and these designs have as much area open as possible without compromising the compression of the land on to the cathode gas diffusion layer. Preferably, each fuel cell board described in any aspect of the invention described herein is connected to an electronic circuit to produce an electrical output, and wherein the connection between each fuel cell board and the electronic circuit is individually switchable. Preferably, the connection between each fuel cell board in the fuel cell and an output line can be controlled by a switch mechanism such as a field-effect transistor (FET) switch, providing power handling and control directly at the cell. Each of these switches can be controlled by individual control lines. This can be by providing a switch on each fuel cell board. Preferably, one or more of the flow paths described herein is routed through the whole body of the layer. Preferably the fluid paths are routed into the insulating layers. Preferably, the fluid paths are routed into the insulating layers prior to copper plating of at least part of the insulating layers. Preferably, one or more of the fluid flow paths are formed within the insulating layer such that the fluid flow path is routed or grooved within the insulating layer without the routing or groove extending all the way through the insulating layer. In embodiments, a fluid flow path is formed within or on an insulating layer such that the fluid flow path is routed or grooved within or through part of the body of one or more faces of the layer. In other words, the fluid flow path is formed without the routing or groove extending all the way through the layer. As can be seen throughout the figures herein, a fluid flow path or so-called depth route, provides a flow path for fluid within a single layer, as opposed to requiring one layer to provide a flow path, and another layer to provide a sealing face sealing the fluid path, as may be required in arrangements of the art. Depth routing to a depth of up to 1mm may be applied in embodiments. Depth routing to a depth of up to 3mm, 2 mm or 1mm may be applied in embodiments. Depth routing of around 3mm, 2mm, 1mm, 0.9mm, 0.8mm, 0.7mm, 0.6mm, 0.5mm, 0.4mm, 0.3mm, 0.2mm or 0.1mm may be applied in embodiments. Depth routing of around between 3mm and 0.1mm, or of around between 1mm and 0.3mm, or of around between 0.9mm and 0.4mm, or of around between 0.8mm and 0.4mm may be applied in embodiments. Here depth routing can be used because it maintains the sealing integrity of any one individual layer. Preferably, depth routing is where the whole layer (e.g. PCB board) is not routed through, i.e. only 10%, or only 20%, or only 30%, or only 40%, or only 50%, or only 60%, or only 70%, or only 80%, or only 90% of the depth of the layer is routed through. Preferably only 10% to 90% of the depth of the layer is routed through, preferably only 20% to 80% of the depth of the layer is routing through, preferably only 50% to 75% of the depth of the layer is routing through. This may also be referred to as depth drilling. Preferably at least 0.1mm of layer remains below the routed or drilled area after depth drilling. Preferably between about 0.10mm and 0.40mm of layer remains below the routed or drilled area after depth drilling. Preferably, at least one of the insulating layers are at least partially coated with a passivating layer after copper plating at least part of the insulating layers. A further aspect of preferred embodiments provides a method of operating a fuel cell. The method comprises controlling the fuel cell temperature, the fuel cell comprising at least one fuel cell board. The at least one fuel cell board is any one of the fuel cell boards described herein, or related to the earlier aspects of the invention. Preferably, the fuel cell board comprises at least one insulating layer, at least membrane electrode assembly (MEA), the MEA comprising an ion permeable membrane and at least one anode and at least one cathode, wherein each or all cathodes are arranged across a first surface of the ion permeable membrane and each or all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane. The fuel cell board comprises heat conductive means in or on the insulating layer to direct heat towards or away from the MEA, and the method comprises transferring heat towards or away from the MEA or the fuel cell board. The fuel cell board of the method may comprise any of the features described herein related to the fuel cell boards above. Preferably, the method comprises transferring heat towards the MEA or the fuel cell board during a fuel cell start-up procedure using the heat conductive means. Preferably, the method comprises transferring heat towards the MEA or the fuel cell board when the fuel cell is not in operation (when fuel is not being provided to the fuel cell boards). This can be after the fuel cell has operated. Heating fuel cell boards when the fuel cell is not operational keeps any residual water from freezing as the system dries out. This also means the fuel cell does not need to heat up again from fuel cell start up. Preferably, the method comprises transferring heat away from the MEA or fuel cell board during operation of the fuel cell using the heat conductive means. Preferably, the method comprises transferring heat to one or more fuel cell boards using heat traces. Preferably, the method comprises using a battery and / or diverting the power of the fuel cell to send a current through the heat trace creating resistance to generate heat. Preferably, heat is transferred to areas of the fuel cell board which experience a lower temperature in fuel cell operation than or compared to those areas of the fuel cell board which experience a higher temperature in operation. Preferably, more heat is transferred to fuel cell boards at the peripheral of the fuel cell stack, adjacent or closer to the end plates or one or more of the last fuel cell boards of the fuel cell stack. The power of the fuel cell itself may power the heat traces, when the fuel cell is in operation. Power from the fuel cell output may be diverted to one or more heat traces (e.g. via a star point). This would be during fuel cell operation, so as to keep one or more fuel cell boards at an optimal temperature. This heat during operation could be delivered asymmetrically throughout a fuel cell stack, for example more heat could be provided to those fuel cell boards at the peripheral of the fuel cell stack, adjacent or closer to the end plates or one or more of the last fuel cell boards of the fuel cell stack. Preferably, the method comprises transferring heat away from the MEA or fuel cell board during operation of the fuel cell using the heat conductive means bringing the heat in proximity to means to absorb or dissipate the heat. Preferably, the means to absorb or dissipate heat is a thermal management fluid, coolant fluid, heat sink, a vent to outside the fuel cell, a heat spreader, a heat pipe, another fuel cell board in the fuel cell, a vent or an opening in the fuel cell housing, or any combination thereof. Preferably, the method comprises transferring heat to or transferring heat from different fuel cell boards or MEAs at a different rate or amount to other fuel cell boards or MEAs in the same fuel cell during fuel cell start up or during fuel cell operation. Preferably, the method comprises transferring heat towards the MEA or a fuel cell board when a fuel cell board is performing at a lower power or operating efficiency than other fuel cell boards in the stack, the method first comprising monitoring the temperature of that fuel cell board. Preferably, the method comprises monitoring the temperature of at least one or multiple fuel cell boards or MEAs of the fuel cell. Preferably, one or more of the fuel cell boards closer to the end plates or closer to the peripheral point(s) of the fuel cell stack or further away from the central fuel cell board or further away from the central point of the fuel cell stack comprise heat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards. Preferably, the two fuel cell boards at the top and bottom of the fuel cell stack or adjacent the fuel cell end plates comprise heat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards. Preferably, one or more of the more central fuel cell boards or those fuel cell boards further away from the fuel cell end plates or the peripheral point(s) of the fuel cell comprise increased heat conductive means in or on the insulating layer(s) to direct heat away from the MEA compared to the other fuel cell boards. A further aspect of preferred embodiments provides a method of controlling fuel cell temperature the method comprising operating a fuel cell according to any the earlier described aspects. The method may comprise operating a fuel cell comprising a fuel cell board according to any the earlier described aspects. The fuel cell board may comprise heat conductive vias, provided (vertically or orthogonally) through at least part of the fuel cell board, and means to transfer heat horizontally along the fuel cell board, e.g. a heat trace or conductive material plating as described herein. The fuel cell may comprise at least one fuel cell board. The at least one fuel cell board may be any one of the fuel cell boards described herein, or related to the earlier aspects of the invention. Preferably, the fuel cell board comprises at least one insulating layer, at least membrane electrode assembly (MEA), the MEA comprising an ion permeable membrane and at least one anode and at least one cathode, wherein each or all cathodes are arranged across a first surface of the ion permeable membrane and each or all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane. The fuel cell board comprises heat conductive means in or on the insulating layer to direct heat towards or away from the MEA, and the method comprises transferring heat towards or away from the MEA or the fuel cell board. The fuel cell board of the method may comprise any of the features described herein related to the fuel cell boards above. An aspect of the present invention provides the use of any fuel cell or fuel cell board described herein. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments of the present disclosure will now be described with reference to the accompanying drawings, in which: FIG. 1 shows a schematic side view of a stacked fuel cell of the prior art; FIG. 2 shows a cross-section of a fuel cell of the prior art comprising a stack of fuel cell boards; FIG. 3 shows a schematic of a single fuel cell board or a single fuel cell module 100; FIG. 4 shows a schematic of two fuel cell boards or two fuel cell modules; FIG. 5 shows the heatmap of a section showing PTH on copper lands in proximity of a reactant; FIG. 6 shows the coolant at the coolant inlet; FIG. 7 shows the coolant temperature at the coolant outlet; FIG. 8a shows a thermal map of a cathode inlet and FIG. 8b shows the heat surrounding the MEA 804 resulting from the exothermic electrochemical reaction; FIGs 9 and 10 show PTH location on the outer surface of cathode plates; FIG. 11 shows normalised iR recorded in correspondence of different current densities. Both curves are normalised against the iR <0.5 A cm'2; FIG. 12 shows the experimental equipment used and conditions to test embodiments; FIG. 13 shows the logarithmic trendline of the two experimental datas; FIG, 14 shows a cathode side of a fuel cell board where a routed air channel is visible; FIG. 15 shows a plate with a heat trace; FIG. 16 shows a stack of insulating layers making up a fuel cell board of an embodiment, and FIG. 17 shows a stack of insulating layers making up a fuel cell board of a further embodiment; FIG. 18 shows an expanded embodiment of a fuel cell board; FIG. 19 shows a schematic of a fuel cell stack of an embodiment; FIG. 20 shows a simplified schematic of the fuel cell board layers of an embodiment; FIG. 21 shows a fuel cell of an embodiment; FIG. 22 shows an expanded further embodiment of a fuel cell board of the present invention; FIG. 23 shows a schematic of plated through holes in the MEA of an embodiment; FIG. 24 shows a schematic of a fuel cell stack of an embodiment; FIG. 25 shows a simplified schematic of the fuel cell board layers of an embodiment; FIG. 26 shows a possible electron pathway in a segmented active area of a fuel cell board; FIG. 27a shows a fuel cell stack according to an embodiment; FIG. 27b shows an alternative view of a fuel cell stack according to an embodiment; DETAIL DESCRIPTION Embodiments will now be described in detail with reference to the accompanying drawings. The same reference signs indicate the same or similar features in different figures and embodiment of the invention, although this is only for reference and is not limiting on the invention. In the following detailed description numerous specific details are set forth by way of examples, in order to provide a thorough understanding of the relevant teachings. However, it will be apparent to one of ordinary skill in the art that the present teachings may be practiced without these specific details. Figure 3 shows a schematic of a single fuel cell board or a single fuel cell module 100. Two insulating layers or PCB boards 101, 102 are shown, with a MEA 103 located between the two boards 101, 102. A gas diffusion layer (GDL) 104 is also present adjacent each side of the MEA. Each board 101, 102 has a layer of insulating material 105, with conductive material plating 107 on the surface adjacent to the MEA 103 and conductive material plating on the surface 108 opposite the MEA adjacent surface. A layer of insulating material 105 plus the conductive material layers 107, 108 may be called an insulating layer, or a PCB board or a conductively plated PCB board. Not all areas of conductive material plating are labelled in FIG. 3. The internal surface and its conductive material plating 107 of each board 101, 102 is proximal to the MEA 103. The external surface and its conductive material plating 108 of each board 101, 102 is proximal to the cooling architecture of the fuel cell. Not all areas of the insulating material are plated, areas of the insulating material 105 can be seen not plated or covered in the conductive material. There are two conductive material coated or plated surfaces; the external is more accessible than the internal surface in contact with the MEA. The conductive materials are heat conductive means, which can conduct heat parallel to the MEA along the fuel cell board, horizontally along the at least one of the fuel cell boards. The fuel cell board has vias or holes 110 shown, which are heat conductive vias. These are heat conductive through holes. They are orthogonal or perpendicular to the MEA. Here these are shown through each layer of insulating material 105. These are connected to both layers of conductive material 107, 108. These vias act as thermal vias, which work with double-sided boards with copper connecting the top and bottom surfaces of the PCB. They can also connect multiple layers of a PCB, creating conduits, outside the MEA region, to dissipate the heat throughout a stack of fuel cell boards. Heat is transferred or conducted through, up or via these through vias. Cooling channels or other cooling areas of the board (not shown) may be located in proximity of the copper surfaces to improve the heat transfer. Fuel cell boards comprising insulating materials with conductive means designed and included as such are unique. Insulating materials prevent indiscriminate conduction of electricity and heat and allow the accurate targeting of the heat removal and heat delivery where it is needed. Here is shown a core of electrical and heat insulant material, sandwiched between conductive material layers, capable of conducting electricity and heat. When considering a PCB fuel cell LT PEM (Low temperature polymer electrolyte membrane), testing has shown that in fuel cells comprising such fuel cell board designs, the internal conductive material surface in contact with the GDL / MEA can reach around 80 to 100°C. Temperature ranges may be different for differently operating fuel cells. To avoid overheating and damage of the MEA the heat may be removed from the centre of the board, for subsequent dissipation through the fuel cell. Cooling systems where a fluid is at a temperature lower than the operational temperature of the FC can be used to remove the heat from the fuel cell module and the stack. These have been previously described, see WO2022 / 106818 and WO2023 / 052789, which are incorporated herein by reference. The greater the AT between the body from which the heat needs to be removed and the cooling fluid the more efficient is the cooling. The cooling channels can be preferable located in proximity of the copper surfaces to improve the heat transfer. Figure 4 shows a schematic of two fuel cell boards or two fuel cell modules 200. Two insulating layers or PCB boards 201, 202 are shown for each board 200, with a MEA 203 located between the two boards 201, 202. A gas diffusion layer (GDL) 204 is also present adjacent each side of the MEA. Routed reactant channels are shown in each board 201, 202. Four channels are shown for each board, not all labelled. Board 201 is an anode board, with anode reactant (e.g. hydrogen) flow channels 211 routed. These provide reactant to the anodes of the MEA 203. Board 202 is a cathode board, with cathode reactant (e.g. oxygen) flow channels 212 routed. These provide reactant to the cathodes of the MEA. Coolant channels 214 are also shown in the anode boards 201, four for each board, not all labelled. Each board 201, 202 has a layer of insulating material 205, with conductive material plating 207 on the surface adjacent to the MEA 203 and conductive material plating on the surface 208 opposite the MEA adjacent surface. Not all areas of conductive material plating are labelled in FIG. 4. The internal surface and its conductive material plating 207 of each board 201, 202 is proximal to the MEA 203. The external surface and its conductive material plating 208 of each board 201, 202 is proximal to the cooling channels 214 and the boards. The external conductive material plating 208 two of the boards 201, 202 is adjacent to adjacent boards. The conductive materials are heat conductive means, which can conduct heat parallel to the MEA along the fuel cell board, horizontally along the at least one of the fuel cell boards. As in FIG. 3, areas of the insulating material 105 can be seen not plated or covered in the conductive material. There are two conductive material coated or plated surfaces; the external is more accessible than the internal surface in contact with the MEA. The fuel cell board has thermal through vias 210 shown, which may be plated through holes. They are orthogonal or perpendicular to the MEA. Here these are shown through each layer of insulating material 205. These are connected to both layers of conductive material 207, 208. Here, two adjacent fuel cell boards 200 and the possible location of cooling channels 214 are shown in relation to the surfaces 207, 208 of the boards 201, 202. Heat generated by the MEA 203 will be conducted by the thermal through vias 210 from the internal surface 207 to the external surface 208 of each board 201, 202. The heat can then be dissipated by the cooling channels 214, as the external surfaces 208 of both boards 201, 202 are closer to the coolant channels 214. The temperature of the external surface 208 should be lower than the internal surfaces 207, as the internal surfaces 207 are adjacent MEA 203 and the external surfaces 208 are more proximal to the coolant channels 214. The thermal via construction can be used very effectively to remove the heat from the MEA region where the electrochemical reaction occurs to the outer surfaces of the fuel cell boards. This heat could then be dissipated to the coolant channels or to end plates, or other such heat sinks. Thermal vias can connect multiple layers of fuel cell boards, conduits, outside the MEA region, to dissipate the heat throughout the fuel cell stack. If the temperature varies between fuel cell boards, the thermal vias can distribute or dissipate heat to even out the temperature of the fuel cell boards. This allows for a more consistent voltage across the fuel cell stack and a more consistent current generation. The thermal vias allow modification of the thermally insulating properties of the insulating material. The thermal vias and conductive material layers enable a three-dimensional heat exchange mechanism. The heat dissipation occurs through a combination of horizontal thermal conduction through conductive material, connected by vertical thermal conduction through an array of thermal vias. Thermal vias establish a low thermal resistance path from the internal copper surface to the external surface of the PCB. This and other fuel cell boards herein have vias annulars or holes shown, which are conductive through holes. These conductive through vias are provided orthogonal to the MEA through at least part of the at least one insulating layer. The conductive through holes act as highly thermal conductive bridge to permit heat to flow from the hotter parts of the fuel cell board, for example from the membrane electrode assembly to the external environment. They will also act to conduct electricity when electrically connected to the MEA (e.g. via other plating on the fuel cell board). If the holes pass through to the depth of the MEA / conductive material plating connected to the MEA (but not through the MEA, as shown in Figure 3 and 4) then current will flow from these from or to one side of the MEA (e.g. from or to one of the cathode or the anode side). Or, these can be drilled through the MEA and act to pass current from one surface of a fuel cell board to the opposite surface of the fuel cell board. These are described in alter figures. These conductive through vias are through holes, and may be plated through holes (PTH), for example copper plated through holes. The terms "vias", "thermal vias", "annulars", "conduits", "heat conductive vias", "heat conduits", "heat conductive conduits", "thermal conduits", "thermally conductive vias" are used interchangeably throughout. When referred to as a "through via" or "through", the vias are found at least partially through a layer, typically an insulating layer. They may also go through multiple insulating layers in a single via, and / or through the MEA when in a fuel cell board. The "means to conduct electricity" or "heat conductive vias" as referred to herein may be plated through holes. "Plated through holes" (PTHs) are holes that form a conduit through one or more insulating material layers, said conduit running substantially perpendicular to the planar surfaces of the fuel cell boards. These are plated with a conductive material, for example copper, to act as a conduit for electricity. The Plated though holes are necessary because PCB material (e.g. FR-4) is electrically insulative so PTHs must be introduced so that electricity can pass through the plates. These may be formed by holes bring drilled through the layer of insulating material (for example a PCB plate) and then lining with a conductive material. For example, they may be lined with a conductive material by an electroplating dip process such that copper lines the edge of each hole. Optional additional steps can occur after electroplating, wherein i) resin can be used fill the remainder of the hole, which is achieved by forcing resin over the PCB such that it flows through any holes present; ii) electroplating dip processing again such that the resin filled holes are capped with copper on both sides; and iii) there may be a mild milling process after this to ensure the surface of the PCB is flat. When these are found through PCB layers they can create continuity between two layers of copper plating on either side of the PCB material. PTHs may be formed through only certain layers of the insulating materials described herein, or through only some layers of the fuel cell boards described herein (for example through just the anode and cathode plates, to be able to carry current to / from the anode / cathode to the outer surface of a layer of insulating material). PTHs may be formed through the whole fuel cell board (for example through both the anode and cathode plate with the same hole, to be able to carry current to / from one surface of the fuel cell board to the other surface of the fuel cell board). The process of creating such plated through holes in a layer of insulating material are as follows: Drilling - Small holes are first drilled into the layer of insulating material substrate at precise locations; Cleaning: After drilling, the holes are cleaned to remove any debris; Plating: The drilled holes undergo a two-step plating process; Electroless plating: The holes are chemically activated to promote adhesion, and a thin layer of copper, is deposited on the hole walls; Electroplating: An additional layer of copper, is electroplated onto the hole walls by immersing the PCB in an electrolyte solution and applying an electric current; and Resin filling: Filling of the holes to protect the hole metallization &prevent the passage of fluids. The "heat conductive vias" as referred to herein may also be conductive nonplated holes, for example holes filled with conductive material. These may be filled with a conductive material such as carbon, resin, metal or a conductive polymer. This removes the need for a plating step in manufacture. The thermally conductive vias may be blind vias. Blind vias are a known component of modern printed circuit boards (PCBs), found in multi-layered PCBs. Blind vias are holes located in the boards which can connect different layers of boards. Blind vias only go part of the way through a board, stopping at specific layer rather than running through the entire board. They go through at least part of a layer. This allows for the more complex and possibly more compact board layouts. Blind vias can be used to conduct thermal or electrical energy between layers while minimizing the number of layers needed. This can reduce the cost and size of the fuel cell board. The thermally conductive vias may be buried vias. Buried vias are a known component of modern printed circuit boards (PCBs), found in multi-layered PCBs. Buried vias are holes located in the boards which can connect different layers of boards. Buried vias differ from blind and through hole-type vias because they are located between two inner layers of the PCB and do not penetrate through either of the two surface of the board. This allows for the more complex and possibly more compact board layouts. Buried vias can be used to conduct thermal or electrical energy between layers while minimizing the number of layers needed. This can reduce the cost and size of the fuel cell board. An insulating layer or fuel cell board may comprise any combination of through holes, blind vias and buried vias. Reference herein to "surface" of a board or insulating layer refers the surface of the board or insulating layer which faces the MEA when arranged to sandwich an MEA, and the surface opposite to that. These are the two largest surfaces of such boards, typically rectangular in shape. The optimal parameters for plated holes to be used as thermal vias can be calculated. The X axis shows PTH diameter plotted against the Y axis of effective conductivity. Based this, the optimal diameter of PTH is around 250-350 pm, preferably around 300 pm. A coating thickness may preferably be between 10 and 30 pm, or preferably around 20 pm. The effective conductivity of PTH as a function of their diameter keeping the plating thickness constant is shown. These are just optimal for the PCB plates utilised in the examples - which have a thickness of between 0.5 to 1.2mm. Optimal parameters may depend on many factors. The number and position of thermal vias in the insulating materials has a direct impact on thermal resistance. Placing the vias as close to the heat source, lowers thermal resistance by improving heat dissipation. The thermal via array in a fuel cell board can be designed in a custom arrangement in such a way that there are distinct operating advantages keeping a fuel cell operating in a thermally optimised way - for example: o a fuel cell board can be designed in such a way that there is a greater concentration of thermal vias in areas where additional cooling would be required (e.g. - towards the cathode outlet); o In addition thermal vias can be located in areas of high local compaction (e.g. - where anode and cathode flow field lands "cross over") because the need to connect two conductive material surfaces, to create a highly effective contact areas with the porous carbon gasdiffusion layer -GDL; o Thermal via design can be engineered to equalise the thermal profile of the fuel cell stack from cell to cell; for example in a staggered fashion, varying configuration from cell to cell; and o Thermal vias can be concentrated in areas where there is greater electrochemical activity and therefore the exotherm is greater than in other section of the board. Testing and modelling has confirmed how the heat is dissipated through the fuel cell boards and channels described herein. Figure 5 shows as an example of a heatmap of a section showing PTH on copper lands in proximity of a reactant flow field. Lighter areas show a higher temperature, darker areas a lower temperature. 600 highlights the PTHs. Figure 6 shows the coolant at the coolant inlet and Figure 8 shows the coolant temperature at the coolant outlet. Lighter areas show a higher temperature, darker areas a lower temperature. 600 highlights the PTHs. Thermal vias are much more effective at transferring heat than the insulating material that the fuel cell boards are made of, as can be seen in Fig.s 5, 6 and 7, where the temperature of the insulating material around the thermal vias is cooler than the thermal vias. Consequentially the reactant flowing in the insulating material channel is cooler than the conductive material (copper) areas in contact with the MEA and the thermal vias. The use of optimally placed thermal vias to provide an effective bridge between copper surfaces is highly desirable for localised thermal management required for effective fuel cell operation. Thermally insulating materials such as FR4 have a very low heat conductivity, two orders of magnitude lower than the copper (copper 350W / mK and FR4 0.25 W / mK); therefore, introduction of thermal vias into insulating materials increased its thermal conductivity. For cooling to be as effective as possible the heat resulting from the exothermal reaction at the MEA needs to be transferred as efficiently as possible to a cooling area of the fuel cell, so it can be transferred externally to the fuel cell stack. Figure 8a shows a thermal map of an example of a fuel cell configuration showing a close-up of cathode inlet, PCB FR4 boards, MEA 804 and copper PTHs 800. The thermal map identifies areas at different temperatures. Lighter gradations indicate higher temperature areas. In this example a coolant inlet channel section (dark rectangle on the left top corner), 802, is also shown. The internal copper surface of the PCB facing the MEA experiences the highest temperature. The temperature of the PCB around the MEA, resulting from the exothermic electrochemical reaction, is higher than the temperature of the PTHs which are very effective at transferring heat to the next conductive means away from the MEA. This heat transfer is more effective where copper features are in close proximity to the cooling section of the board. The copper architecture (comprising copper lands facing the MEA collecting the current and the heat, PTHs and the copper external PCB surface) conducts the heat to the cooling channels to be dissipated more effectively. Copper architecture in conjunction with the cooling channels synergically draw and dissipate the heat very effectively from one copper surface in contact with the MEA to the other copper surface in proximity of the cooling channels. Figure 8b shows instead an example of a cathode outlet where the partial pressure of the oxidant is lower, the heat exchange fluid is balancing the PCBFC operational temperature and the temperature of the area surrounding the MEA has decreased. PTH 800 continue to transfer heat through the module at the same rate. The effectiveness of the PTHs as thermal vias can be seen in the following two experiments. Two PCB single layers were prepared for assessing the effectiveness of the PTHs as heat bridge. The second experiment uses double PTH density than the first experiment. All of Figures 9 and 0 show PTH location on the outer surface of cathode and anode plates. Rows of PTHs are noted with 900 in these figures, only two rows in each is labelled. Figure 9 shows PTH rows on a cathode plate, Figure 10 shows PTH rows on a cathode plate. The cathode plate Figure 10 has double the rows of PTHs, double the density of PTHs. Here it is demonstrated that doubling the amount of PTHs improved the heat transfer from these boards of insulating material. The graph in Figure 11 shows normalised iR recorded in correspondence of different current densities. Both curves are normalised against the iR <0.5 A cm'2. The iR in the first experiment increases from the nominal because the PTH arrangement cannot remove heat as effectively, thus increasing electrolyte resistance because the fuel cell cannot retain moisture, whereas in the second experiment iR decreases because the heat is being removed and moisture in electrolyte is retained. This behaviour is more prominent at higher current densities, where the overall ohmic resistance IR has almost halved from 70 mQ cm2 to 35 mQ cm2 as a result of doubling the amount of PTH, which has the improved ability to remove heat from the cell. IR thermographic evaluation- was also conducted to determine the efficiency of heat removal related to the quantity of PTH. The fuel cell used for the experiments to generate the data for Fig. 11 was opened and only the cathode side comprising external copper surface / FR4 / internal copper surface facing the MEA / GDL was used for the experiment. Figures 9 and 10 show the two different samples used in the experiment to evaluate the efficacy of the PTHs in transferring heat. The board of Fig. 9 has a density of 9PTH / cm2 the board of Fig. 10 has a density of 17PTH / cm2. Figure 12 shows the experimental equipment used and conditions to generate the graph of Figure 11. Wood 910 has a heater mat 913 placed on it. A silicone adhesive pad 912 is placed on this, with the board sample 911 placed on that. This is inside black carton box 914 with black curtain 915. The IR thermographic experiment was conducted using a thermal camera FLIR A6750sc, set at a distance of 0.5 m from the PCB sample surface. The external surface of the PCB layer was blackened to create an even and high thermal emissivity (emissivity= 0.98) and the plate was placed on a heat source, with the internal copper layer, normally facing the MEA, facing the heat source, and heated up to 60C. The PCB plate, the heat source [26W] and the camera were placed in a dark environment, in a black box 914 under a black curtain 911, to avoid reflections, maximizing the emissivity and avoiding the narcissus effect, Fig. 12. Once the heater reached 60C the sample 911 was placed on the silicon heat pad 912 and allowed to equalised to the temperature of the heater. Effective adherence of the PCB plate 911 to the pad was ensured by a silicon adhesive pad 912. The PCB internal copper surface is at a constant temperature (T_heater), T_heater = 60°C, Where the measured T is the mean temperature obtained from a selected rectangular region of interest from the external surface, T(t), where t=time. The difference in PTH number between Exp A and Exp B is 170 and 320, corresponding to 9 PTH / cm2 and 17 PTH / cm2 respectively. The results are displayed in Fig. 13, showing the logarithmic trendline of the two experimental data. From the plotted experimental data, a logarithmic function representing the trend temperature increase of the outer copper surface on the PCB sample is interpolated. T pthexpb^ = 5.6014 ln(t) + 33.208 T pthexPa^ = 7.4722 ln(t) + 24.483 Disregarding the contribution of convection at the measurement area, d in an environment with calm air at ambient temperature. The following equation can characterise the phenomenon: 9T / 9t= o VA2 T a = k / QCp k=thermal conductivity, Cp (1) Where T is Temperature, t is time, a is the thermal diffusivity. It is assumed that the two proposed designs, in terms of thermal behaviour, have a negligible difference in the trend of the temperature distribution and that the only difference in the distribution is due to its linear coefficient, i.e., thermal diffusivity. Accordingly, the temperature Laplacian is assumed to be constant to solve a two-equation system: VA2T=const (2) Both configurations are based on copper surfaces connected by thermal vias. Assume both configurations to behave thermically homogeneously: cp_effective=vol%_FR4 cp_FR4 + vol%_Cu q>_Cu (3) Where cp is a property linked to the thermal transfer described here in the PBC sample, where FR4 is an example of insulating material and Cu stands for copper. Using the finite difference method and Equation (2), where Ti and T2 and ti and t2 are taken from the experimental data for the sample with the higher amount of PTHs, as this system is more akin to the assumptions made that the material PTH + FR4 between the 2 copper surfaces behave homogeneously. aeff const (4) Being the thermal property <p =f(keff, Qeff, Cpeff, aeff) known, const= 7^2 T can be obtained. Once demonstrated the relationship reflects the experimental observation for ExpB, the same process can be repeated for ExpA. T1 and T2 at 5 time tl and t2 are used to obtain const= VA2 T. T2, experimentally measured, can be predicted using Equation 4. T2, as temperature of the external Cu surface, at each time tn can be calculated as function of the effective conductivity of the PCB with different density of PTH and keff, where keff depends on the volume of PTHs / volume of PCB, provided the io PTHs density is sufficiently high to continue to consider the FR4-PTH combination an homogenous material. ID model is used to describe the physical observations, where the following relation is respected: W = - keff with keff = vol%FR4 kFR4 + vol%Cu kCu (5) 15 Where: (Table 2) Material Description Sample Thermal conductivity k(W / mK) Thermal diffusivity o=k / eCp ExpA Experimental model 24.1 W / mK 1,002 xlO’5 m2 / s ExpB Experimental model 31.5 W / mK 1,253 xlO'5 m2 / s Cu literature 400 W / mK 1.14 x IO'4 m2 / s FR4 literature 0.3 W / mK 1.47x IO'7 m2 / s Table 2 shows the difference in thermal conductivity and thermal diffusivity of the two PCBs used in ExpA and in ExpB with 9 PTH / cm2 and 17 PTH / cm2 respectively. At t=5 sec the temperature of the external copper surface with a PTH density of 9 PTH / cm2 corresponds to T=37.87C and the relationship taking into account the calculated thermal conductivity k, and the thermal diffusivity o, at 6 sec return = 38.36C. The experimental values show it is possible to approximate the material [FR4 + PTHs] as a homogeneous medium when the density of PTHs is above a certain number, deemed necessary to carry out a certain heat flux corresponding to 17 PTH / cm2. However, the mathematical relationship enables the correct calculation of a predicted temperature also for active area with a PTH density of 9PTH / cm2, lower than 17PTH / cm2. Heat transfer property of thermal vias can be improved by altering the pattern and thickness of the conductive material that the thermal vias are thermally connected to. Conductive material plating on the boards is typically between 20 and 50 pm, preferably around 35 pm when it is metal plating such as copper. The location and quantity of thermal conductive vias can be specifically engineered to remove different amount of heat from different areas of the fuel cell boards, for example from well-known heat spots, a challenge which needs addressing in fuel cells. For example the particular aggressive environment of the cathode outlet in a cross-flow FC. Figure 14a shows an example of cathode side of a fuel cell board where a routed air channel is visible. Thermal vias are visible in the copper lands facing the MEA as small circles / dots. Thermal vias are a versatile feature to conduct heat and electricity and can be not only arranged with a more or less density in accordance to the heat and electricity they need to manage but can also be confined to the depth of the fuel cell board or either the cathode or the anode without piercing the MEA, or they can be drilled throughout the entire fuel cell board to transport heat and electricity from a board to the adjacent one using the real estate of the board and the correspondent spacers between boards connecting the fuel cell boards within fuel cell stack. These can be buried or blind vias, as described herein. Thus, as demonstrated herein, heat conductive means which conduct heat parallel to the MEA or horizontally along the fuel cell board (e.g. copper plating) can be combined with heat conductive vias (e.g. PTHs) to help transfer heat away from fuel cell board MEAs, improving performance. Heat can also be provided to (as opposed to away from) a fuel cell module via designed heat traces. Heat can be provided and not just removed from the fuel cell board module and / or stack. For example, this may be when the operational condition of the fuel cell are suboptimal, such as in cold start mode. Additionally or alternatively, heat traces could also be used to help the fuel cell stack to reach homogeneously an optimal operational temperature by supplying heat selectively to fuel cell modules performing less efficiently; for example fuel cell modules positioned at the proximity of the endplate may struggle to heat up as quickly as the rest of the stack. This could be as part of a cold start program, for example. A heat conductive medium (e.g. heat traces) within an insulating material core, or sandwiched / placed between insulating material layers, can also be used to carry heat to fuel cell boards or fuel cell board stacks to raise the temperature of the module to operational temperature. This can be done for all modules in the stack using the same heating exchange A°C / s [same heat trace -thickness and length], or different areas of the stack may be engineered [different thickness of the conductive material, e.g. copper thickness] to receive a greater amount of heat; for example area of the fuel cell stack which may often be colder than the rest of the stack, for example peripheral modules in proximity of the end plates. End plate, normally in Aluminium can work as heat sink, leaving the adjacent fuel cell module at lower temperature than the optimal for the fuel cell. A cold start program can use any source of stored energy, for example a battery, to provide the system with the required power to reach the stack operational temperature. In addition, when the fuel cell stack is operational, thanks to the insulating nature of the insulating material core, it is possible to use a conductive material trace, separated from the other fuel cell electrical circuits to independently raise the temperature of the fuel cell modules which due to the configuration of the fuel cell are predominantly operating at lower temperature than the rest of the fuel cell, for example those in the proximity of the end plates. The environment of a fuel cell in operation contains water. In cold temperatures, water remained in the fuel cell could crystallise as particle of ice and melt when the cell is powered during the cold start. When a heat trace lays on the same surface of the copper surface conducting electricity via the main fuel cell circuit, it can be separated by a route removing the copper and exposing the non-conductive insulating material core, to avoid any possible shorting of the fuel cell module. However, if residual water droplets of a diameter sufficient to equate to the rout width and bridge the two different circuits (external power to bring the fuel cell up to operational temperature and the fuel cell main circuit), it could short the cell. To avoid the possibility of water entering the system, the copper trace needs to be embedded into the PCB- fuel cell module, sandwiched between layers of insulating material or found within an insulating material layer. Thin layers of insulating material can be used so as not to affect the power density of the stack. Thin insulating materials are also more effective at conducting the heat throughout the PCB- fuel cell module from the heat trace, acting as less of a block to the heat from the trace transferring to the MEA. A heat conductive material can be patterned into a heat trace to conduct heat as evenly as possible. For example, copper plated PCB could be etched in a pattern designed to distribute the heat as evenly as possible, as shown in Figure 15. The lighter colour of the heat traces shown all over the surface of this PCB board. The thickness and width of the heat trace determine the resistance and therefore the heat developed and delivered by the feature. Table 3 shows copper traces, for example, parameters in relation to their resistance. A heat trace may be 50 pm to 600 pm width, preferably 100 pm to 550 pm width, preferably 150 pm to 500 pm width, preferably 200 pm to 450 pm width, preferably 250 pm to 425 pm width, preferably 300 pm to 400 pm width, preferably 320 pm to 370 pm width, preferably 330 pm to 360 pm width. 'Width' refers to the horizontal width of the trace. A heat trace may be 18 |jm to 50 pm in height, preferably 22 pm to 45 pm in height, preferably 24 pm to 40 pm in height, preferably 28 pm to 35 pm in height. 'Height' of the trace refers to the height of the trace from the layer of material it is on. This may be referred to as 'thickness'. Heat traces are lines or tracks of conductive material e.g. copper, of a certain thickness. The thickness is related to the resistivity. For example to carry more electricity you need thicker wires otherwise you build up too much resistance. Here the goal of the traces is to build resistivity to generate heat. Lines / traces are very versatile and can be designed to have higher density [e.g. through number of turns in the serpentine] in certain areas and lower density in others. In the systems described herein, copper will be exposed not only to humidity but also to the acidic environment created by the hydrogen ions, therefore to avoid the formation of copper ions, which can migrate to the membrane and deplete the performance of the fuel cell, a passivation layer may be employed. A passivation layer may be placed over the copper trace, for example a passivation ink, for example a carbon ink or any other such layer as described herein. These heat traces or heat trace layers may be located in the anode plate of the fuel cell boards. Trials show that a trace developing a resistance of 15-19 ohms raises the temperature of the stack sufficiently to support the cold start mode for a fuel cell stack. A battery 8V could be a sufficient source of power for this. The time required for the heat trace to discharge the necessary heat over time, is dependent from the environmental conditions. The power of the fuel cell itself may power the heat traces, when the fuel cell is in operation. Power from the fuel cell output may be diverted to one or more heat traces (e.g. via a star point). This would be during fuel cell operation, so as to keep one or more fuel cell boards at an optimal temperature. This heat during operation could be delivered asymmetrically throughout a fuel cell stack, for example more heat could be provided to those fuel cell boards at the peripheral of the fuel cell stack, adjacent or closer to the end plates or one or more of the last fuel cell boards of the fuel cell stack. When connected to a battery of 8V an individual modules operating at suboptimal temperature such as in cold start operational mode could receive a burst of power of up to 50 W, or more,to kick start its activity. The heat traces may all be connected in parallel, so if the 8 V from the battery is applied, the power will be around 16W supplied. The heat traces could also help to improve the performance of the stack when the stack is at suboptimal temperature. In this case the fuel cell itself can power the heat traces and about 20% of the available power to input SOW in the system for as long as the system need to get up to the performance required and stop when the parasitic load is too high for the energy balance of the fuel cell. Figure 16 shows a stack of insulating layers making up a fuel cell board 1000. 1003 shows an MEA sandwiched between two insulating layers / plates 1001 and 1002, 1001 being a cathode plate and 1002 being an anode plate. These are layers of insulating material as described herein. 1010 is a further layer of insulating material which comprises the heat traces 1020 as described herein. These can act to conduct heat to the MEA, though the anode plate. The heat traces are sandwiched between the anode plate and the further insulating layer 1010. The heat trace plate may look like the plate shown in Figure 15. This fuel cell board has a conductive vias 1030 which can act to conduct the thermal energy to the heat trace from elsewhere in the fuel cell (i.e. from a heat source or a battery to send a current through the heat trace creating the resistance to generate heat). These can also pass heat through the board. These thermal vias can pass heat from this fuel cell board to other fuel cell boards. Vias 1030 can be heat conductive vias as described herein, for example plated through holes. Figure 17 shows a similar fuel cell board to Figure 16. However in this fuel cell board 1100, the heat trace 1020 is not connected to heat conductive vias, but an edge of plate connection to a further insulating layer 1040. These edge of plate connection to further insulating layers are conductive material capable of transferring the thermal energy from one layer to another, which are wrapped around the edge of the plate. These may be metal plating, for example copper. They connect to further conductive means on other insulating layers, to transfer heat to the MEA or to other plates in a fuel cell stack. The heat traces of adjacent fuel cell boards may be connected to one another for example through vias, which are plated or filled with heat conductive or electrically resistant material as described in relation to the heat traces. Or, the heat traces may be connected by the edge of plate connections as described in relation to Figure 17. Heat traces may be connected in series or connected in parallel. The heat traces may also be individually switchable by any mechanism known in the art, so that heat traces from one or more fuel cell board may be turned on or off, whilst other traces may remain on or off (on being heating and off being not heating). The temperature of a fuel cell board can vary across the board due to a number of factors. For example, if the location on the fuel cell board is near the exit of a heat exchange fluid (e.g. coolant) fluid flow, then that area of the fuel cell board is likely at a higher temperature as the heat exchange fluid is likely warmer. Further for example, if the ion permeable membrane on the board next to a location in question is locally dry, then there will be a decrease in fuel cell performance, there will be a lower voltage for equivalent current which means more waste heat will be generated, and this location of the fuel cell board may have a higher temperature than other areas. The humidity of a fuel cell board can vary across the board due to a number of factors. For example, typically those areas of a fuel cell board with a higher temperature (as described above), will have a lower humidity. Water is generated by the cathodes of a fuel cell board, but this can diffuse to the anodes of a fuel cell board. At the inlet for the reductant fluid (e.g. H2 gas) there is typically more water generated, as the fuel concentrations are higher and because the system is wetter. Further, H2 may be re-circulated in fuel cell stacks, and re-circulated H2 fluid may have a higher water content then previously circulated H2. This may diffuse to drier areas of the fuel cell board. Generally, an MEA with higher humidity will have lower resistance and achieve higher current density for the same voltage. Generally, the flow directions of the fuels and heat exchange fluids can affect humidity variations across fuel cell boards. But there is typically always some sort of humidity variation across a fuel cell board in normal operation. Fuel concentrations or partial pressure of reactants can vary across a fuel cell board due to a number of factors. For example, the concentration of reactant in the fuels (the reductant fluid or the oxidant fluid, e.g. H2 and 02) decreases as the fuels react with the anodes and cathodes across the fuel cell board. The number or frequency of the means to conduct electrical current to or from the anodes, or the layout of the means to conduct electrical current from one face of the fuel cell board to the other face of the fuel cell board can vary across a fuel cell board to account for variance in the anode and / or cathode design across the fuel cell board. The number or frequency of the heat conductive means (i.e. the heat conductive vias) can vary across a fuel cell board to account for all of these variances. 'Fluid path', 'fluid channel', 'flow path', 'fluid flow path' 'fluidic path', 'flow field' and 'channel' may all be used interchangeably herein and may be substituted for one another herein. They all refer to means by which fluids can flow or travel along, down or through. Fluids may be substantially directed, either with or without assistance, along fluid flow paths, channels or the like. In operation, a fuel cell can be enclosed in a housing and is sealed from the atmosphere. Reactants are fed into the fuel cell channels through sealed connections. Seals may, for example, be made of Polydimethylsiloxane (PDMS). In particular, fuel or reducant (e.g. H2) and oxidant (e.g. air) are fed into appropriate fluid channels of the fuel cell stack, with fuel being supplied to the anodes and oxidant to the cathodes. The electrical current thus formed can be taken directly or the output of the fuel cell board. A constant power output of the stack may be achieved in a variety of ways. For example, all fuel cell boards may be loaded at all times. Alternatively, the fuel cell boards may be divided into groups and these groups may be "switched on" in turn in a synchronous manner (i.e. switching occurs at a defined time for all fuel cell boards). The fuel cell boards may also be switched in an asynchronous or quasi-asynchronous manner - i.e. each fuel cell board is connected and disconnected to the load for a defined period and frequency individually specified for each fuel cell board. By switching the fuel cell boards so that they are only connected to the load for a proportion of the time according to a duty cycle, the output power of the stack can be continuously modified. For example, if over a given sample period of time only 50% of the fuel cell boards are connected to the load, then the output power of the fuel cell stack will be similarly reduced. The manner in which this 50% is achieved may be brought about in a multitude of ways - for example half of the fuel cell boards may be disconnected from the load and half connected for the entire period; alternatively all fuel cell boards may be connected to the load, but each connected for only half of the sample period. Alternatively again, half of the fuel cell boards may be connected to the load for one quarter of the sample period, and the other half for three quarters of the sample period etc. The choice of the specific scheme or duty cycle used may depend on the performance of individual fuel cell boards, the need to avoid localized heating or 'hot spots', the need to avoid flooding of cathode sites with product water, the need to prevent dehydration of the membrane, or the need to counteract poisoning of the electrodes. It will be noted that the duty cycle may be predetermined or may be controlled in real time based on monitored performance of the fuel cell, for example in a closed feedback loop with a voltage measuring apparatus. Part-time use of fuel cell boards may also improve efficiency as one can achieve optimum load conditions and power conversion for each individual fuel cell board rather than for the fuel cell stack which is a limitation of current designs. By including additional switching and filtering components on the fuel cell boards, a smoothly varying output, for example a sinusoidal wave, may be obtained, in addition to simple "changeovers" or steps from one potential to another. Each fuel cell board can carry its own electronic circuitry, with each module feeding the power into an electrical bus. That is, each board contains its own power electronics and controller. The latter monitors the performance of the fuel cell electrodes, local humidity and temperature. It can also control the shape memory alloy (SMA) valves to throttle the flow of reactant to the electrodes on that board, as described in more detail below. Thus the power electronics can be put directly onto each horizontal board. In this manner, the status of each electrode can be monitored for degradation. This information gives feedback to enable the electronics to be modulated so a particular board of electrodes can be used less, thereby slowing the degradation process, or by completely shutting down a board of electrodes. This control enables the protection of underperforming boards, thereby increasing the longevity of the entire fuel cell stack. FIG. 18 is a schematic diagram of one view of an expanded PCB fuel cell board 2000. Fuel cell board 2000 is shown expanded for the purposes of this figure, to show the membrane electrode assembly layer 1103 separated from cathode plate 1101 and anode plate 1102. The cathode plate may be the first insulating layer as described herein. The anode plate may be the second insulating layer as described herein. This board may have the heat conductive means in or on any of the present insulating layers to direct heat towards or away from the MEA as described herein. MEA layer 1103 has ten cells or MEAs 1113 which are visible in a planar arrangement. Each MEA 1113 comprises an ion permeable membrane, an anode and a cathode. Two MEAs 1113 are labelled in FIG. 18, but all 10 are in part visible. MEAs 1113 of this embodiment have all cathodes are arranged on a first surface of the ion permeable membrane and all anodes are arranged opposite the cathodes on the other surface of the ion permeable membrane. Only a single membrane is present. In this embodiment MEAs 1113 are laminated between the cathode plate 1101 and anode plate 1102, but are shown separated / expanded in this figure just to show their presence. The lamination process is described later. Here anodes face anode plate 1102 (face up in FIG. 18) and cathodes face cathode plate 1101 (face down and not visible in FIG. 18). This shows one embodiment of an MEA suitable for use for the embodiments described here. Other MEA designs, shapes, orientations would be known to a person of skill in the art and understood to be suitable with the present embodiments. Variation in MEAs can be as described herein. Just variation in size of MEAs is visible in this embodiment. The MEA layer 1103 comprises a sealing / lamination material such as prepreg, visible in MEA layer 1103 as the non-MEA 1113 area. 1113 shows the MEA which can include a gas diffusion layer. The ion permeable membrane extends beyond this area for a small distance (around 0.2 mm all the way to the edge of the module), to form a seal with the prepreg. The ion permeable membrane is sandwiched between prepreg in this area. Cathode plate 1101 and anode plate 1102 here are partially copper plated printed circuit boards (PCBs), but in embodiments herein could be layers of any insulating material as described herein. In a fuel cell board 2000 the cathode plate 1101 and anode plate 1102 are laminated together with the MEA layer 1103, the MEAs are located between the cathode plate 1101 and anode plate 1102 to form a fuel cell board 2000. In FIG. 18 only inner face 1101a of cathode plate 1101 and outer face 1102b of anode plate 1102 are visible. The inner faces of both cathode plate 1101 (face 1101a shown in FIG. 18) and anode plate 1102 are plated with copper and routed with flow field 1111 designs, with a passivating ink screen printed over the flow field surfaces on the inner faces of both plates 1101, 1102 to prevent degradation. Only the flow cathode flow fields 1111 are visible on the inner face 1101a of cathode plate 1101 (one flow field 1111 is labelled in FIG. 18, but multiple flow parallel field paths 1111 are visible). In FIG. 18 the flow fields for the anode plate 1102 are not visible, they are on the not visible inner face 102a of the cathode plate 1102. The flow fields 1111 on the cathode plate 1101 may be the first fluid paths as described herein and the flow fields on the anode plate 1102 may be the second fluid paths as described herein. In the specific embodiment displayed in FIG. 18, but also generally in all embodiments, flow fields are routed into the insulating material layers to provide paths for the reactants (for example air, hydrogen) to be supplied to the cathodes and anodes. Oxidant fluids flow only to one or more of the cathodes and reductant fluids flow only to the one or more of the anodes of each fuel cell board. Reference herein to 'oxidant fluids' refers to fluids that will react at the cathode, for example air or oxygen. Reference 'reductant fluids' refers to fluids that will react at the anode, for example hydrogen. Here, the flow fields are channels routed into the surface of the insulating material layers, but are not routed through the whole body or volume of the board. They are just routed into one surface, no flow field or channels are found on the opposing face to the face into which the fields are routed. The present arrangement allows effective separation of the reactants for the anodes and the cathodes. For example, as visible in FIG. 18, flow fields 1111 on cathode plate 1101 are only routed into face 1101a of anode plate 1101, they are not routed through the whole body of the plate through to face 1101. The same for the flow fields (not visible in FIG. 18) on the anode plate 1102. Thus, no flow field is visible on the outer face 1102b of the anode plate 1102 (and no flow field would be visible on the outer face 1101b of cathode plate 1101). When the boards are laminated the flow fields are located over the relevant part of the MEAs 1113 (the anode flow field over the anodes, the cathode flow fields over the cathodes), so as to supply the relevant reactant directly to the anodes and the cathodes. The pressure of the reactant fluids supplied ensures a reaction at the anodes and the cathodes. Recants will enter one side of the plate and leave via the opposing side of the plate, in this embodiment with parallel flow fields. Various flow field patterns and entry and exit points on a plate to the plate will be known to those of skill in the art. For example, flow paths can be serpentine, circular or just channels straight across a plate (i.e. parallel). Flow fields can enter and leave by the same side of a plate or opposing sides or corners of the plates. It is advantageous to have flow of reactants enter and leave opposite sides of the plate so that the reactant manifolds can easily be separated on opposing sides of a fuel cell. The outer faces 1101b, 1102b of plates 1101, 1102 are also copper plated and are routed with the desired copper design. The plates are then drilled with holes for the various manifolds and flow fields. After lamination, the outer surfaces 1101b, 1102b of the cathode pate 1101 and the anode plate 1102 have further holes 1103, 1104 drilled or routed. These holes 1103, 1104 provide access into their respective flow fields 1111 for reactant fluids (e.g. air and hydrogen) to be supplied from the manifold and back into the manifold, to and from (respectively) the flow fields 1111. On the cathode plate 1101 reactant air is supplied and exits the end of cathode flow fields 1111. Cathode manifold 1105 supplies compressed reactant air, and it is via cathode manifold 105 reactant air exits cathode plate 1101 and the fuel cell board 2000 as a whole. The air comes from the atmosphere i.e. outside of the fuel cell, but it enters the fuel cell system via an air compressor (as opposed to a fan as may occur in later embodiments). This enables higher pressures of air to be achieved, although there is an increased parasitic energy cost to operate such a compressor over a fan. Heat exchange fluid manifold 1107 and anode manifold 1109 are also visible in FIG. 18, and are also drilled or routed into the plates after lamination. Anode manifold 1109 supplies reactant hydrogen, and it is via anode manifold 1109 reactant hydrogen leaves anode plate 1102 and the fuel cell board 2000 as a whole. Heat exchange fluid manifold 1107 and cathode manifold 1105 are also visible in FIG. 18, also drilled into the plates after lamination. These supply cathode reactant fluid and a heat exchange (e.g. coolant) fluid to the fuel cell board 2000. Generally, for all embodiments herein, manifolds of any appropriate size, dimension and shape supply and collect the reactants and heat exchange fluids, or any other relevant substances, into and out of the inlets and outlets of fuel cell boards. Vertical channels up and down fuel cell stacks are connected to manifolds along the two opposed edges of the stack, which supply and collect the reactants, heat exchange fluids etc. to and from boards. The plates may also have holes drilled or routed for bolting holes, and / or alignment pins can be inserted into these. FIG. 19 shows a schematic of a fuel cell stack of an embodiment. Four fuel cell boards 2000 are shown, four single cell plates 2000, four cells in series. Cathode plates 101 and anode plates 102 are not separately shown in FIG. 19 but one of each is present in each fuel cell board 2000 (there would be four of each in a stack this size). In FIG. 19 three coolant plates 300 can be seen disposed between four fuel cell boards 2000. Anodes 2 and cathodes 3 are shown, three of each are labelled in FIG. 19, each fuel cell board 2000 has 11 anodes 2 and 11 cathodes 3 arranged in horizontal planes of only anodes 2 and only cathodes 3 in each horizontal plane. Anodes 2 are disposed opposite cathodes 3, with a single electrolyte membrane la between anodes 2 and cathodes 3. The layout of the anodes and cathodes in this embodiment is similar to that of a traditional fuel cell, because there is a single electrode in a plane. In typical bipolar fuel cells an MEA is sandwiched between bipolar plates to give a single cell at each layer. Bipolar plates are typically made with electrically conductive materials such as graphite or metals. Here, uniquely, traditional bipolar plates are replaced by the cathode boards 101, the anode boards 102 and the coolant plates 300, all here made of insulating material, for example PCBs. Coolant plates (LCP, 300) are conductive as they are copper coated and have plated through holes (not visible in FIG. 19). As well as the cathode plate 101 and anode plate 102 not being shown, also not shown are the plated through holes 120 through the cathode plates 101 and anode plates 102 which electrically connect anodes 2 and cathodes 3 to the liquid coolant plates 300. Thus, the liquid coolant plates 300 connect adjacent anodes 2 and cathodes 3. In this embodiment, there are no plated through holes though the electrolyte la. By virtue of the conductive coolant plate 300, current does not need to cross the electrolyte layer, but moves laterally from anode to cathode parallel to the horizontal plane of electrodes. Consequently, no through-membrane connections are necessary for the current to flow. Plated through holes 52 are shown passing through just the anode 2 or cathode 3 layers, just highlighted in one board (the bottom board) to show these. FIG. 20 shows a simplified construction schematic of a board of the embodiment of FIG. 19. Fuel cell boards are constructed by layering up of MEAs, insulating layers and an epoxy resin prepreg (herein 'prepreg')- In construction of a fuel cell board 2000 of this embodiment, the MEA 1113 is sandwiched between two layers of prepreg 9000, then the cathode and anode plates 1101, 1102 are laminated either side of those two layers of prepreg 9000. These layers are laminated all together. Plated through holes are then drilled into the anode 1102 and cathode plates 1101. After this is complete the final drills and routes expose the anode flow fields and cathode flow fields as well as drills for gas manifolding, bolting holes, and alignment pins are made. Use of a sealing materials such as prepreg, and the use of insulating materials, ensures that the MEA is sealed from anything not deliberately directed to the components of the MEA by the channels in the insulating boards (e.g. anode and cathode plates) directly adjacent to the MEAs. This is an advantage of insulating material technology, it allows quick, simple and cheap construction of such structures. Use of lamination with for example an epoxy resin prepreg also maintains compression of the gas diffusion layer of the MEAs, an important component in maintaining fuel cell performance, providing a sufficiently low resistance electrical path without compromising distribution of reactant fluids. Boards which are laminated with a specific lamination process, involving careful pre-cutting and alignment of materials, along with bespoke heating, cooling, pressure and washing cycles. Once fuel cell boards of this embodiment are constructed, they can be made into fuel cell stacks. These are modular and made of two components, the fuel cell boards and the coolant plates. Stacks begin and terminate with an endplate which provides compression through the stack as well as sealed ports to connect fuel, oxidant, and coolant. Means to remove excess current can also be used at either end of the stack to take off the significantly high current when necessary. A stack can be built with a repetitive sequence of coolant plates and fuel cell boards. After and before the two end plates, stacks begin and terminates with a coolant plate, acting to cool both ends of the stack. The stacks shown throughout are held together with bolts which also provide compression for the seals between modules, however any means to hold stacks together compressed, or any means to seal fuel cell boards, coolant plates, or modules together, and end plate types known in the art, may be utilised. Gaskets to seal manifolds or other parts of the fuel cell stack together can be used, if necessary, but may not be necessary in such a stack. A fuel cell stack 30-1 of the of an embodiment is shown in FIG. 21. The fuel cell stack 30-1 is encased in a fuel cell casing with end plate 31 visible. Present in this embodiment are eleven liquid coolant plates 300 and ten fuel cell boards 200. As shown in FIG. 21, the fuel cell has two cathode inlet / outlets 32, two coolant inlet / outlets 33 and two anode inlets / outlets 34. Cathode inlets 32 will be connected to a compressed air compressed air canister or an air compressor to supply compressed air to act as an oxidant to react at the cathodes in fuel cell operation. Cathode outlets 32 will be connected to an exhaust to the atmosphere. Sometimes cathode outlets 32 will be connected to an exhaust via a humidifier such that the water produced in the fuel cell can be used to humidify the air going into the stack. This is achieved via passing the incoming and outgoing fluids over a water permeable membrane. Anode inlets 34 will be connected to a hydrogen cannister, to supply hydrogen reactant to the anodes to act as a reductant gas in order to fuel the fuel cell operation. Anode outlets 34 will be connected to an exhaust to the atmosphere or an anode recirculation system. An anode recirculation system can comprise a water trap (to remove accumulated water) and a hydrogen pump or orifice which increases pressure such that any unused hydrogen can be put back into the stack. Endplates 32 can act to compress the fuel cell and to seal it, to prevent any fluid leakage in operation. Fuel cells are bolted together to ensure compression. A further embodiment of the invention is shown in FIG. 22. FIG. 22 is a schematic diagram of one view of an expanded fuel cell board 400 of an embodiment. Fuel cell board 400 is shown expanded for the purposes of this figure, to show the membrane electrode assemblies (MEAs) 113 separated from cathode plate 401 and anode plate 402. This board may have the heat conductive means in or on any of the present insulating layers to direct heat towards or away from the MEA as described herein. Eleven cells or MEAs 113 are visible in a planar arrangement. In the earlier described embodiment, each MEA 113 comprises an ion permeable membrane, an anode and a cathode. In MEAs 113 of this embodiment all anodes are arranged on a first surface of the ion permeable membrane and all cathodes are arranged opposite the anodes on the other surface of the ion permeable membrane. Only a single membrane is present. In this embodiment MEAs 113 are laminated between the cathode plate 401 and anode plate 402, but are shown separated / expanded in this figure just to show their presence. The lamination process is described elsewhere. Cathode plate 401 and anode plate 402 are PCBs, but they may be any such insulating material. In a fuel cell board 400 the cathode plate 401 and anode plate 402 are laminated together with the MEAs 113, the MEAs 113 between the cathode plate 401 and anode plate 402 to form a fuel cell board 400. In FIG. 22 inner face 402a of anode plate 402 is visible. The inner faces of both cathode plate 401 and anode plate 402 (401a and 402a respectively) are plated with copper and here only the anode plate 402 is routed with a flow field 112 like designs, as described in the earlier embodiment of the invention. The cathode plate 401 has an alternative flow field design, consisting of many drilled holes in the face of the plate, as described later. Both plates 401, 402 have a passivating ink screen printed over the inner faces 401a, 402a of both plates 401, 402 to prevent degradation. Flow fields 112 are visible on the inner face 402a and the anode plate in FIG. 22. Two flow field paths 112 are labelled in FIG. 11a and in total three flow field paths 112 are visible in FIG. 11a in the form of a serpentine loop traversing the face 402a of the plate 402. Multiple single flow fields 112 make up the 'flow field' for the plate 402 and are shown as serpentine loops traversing from one corner of the plates 402 to the other corner of the same plate 402. Anode flow field provides a path for the reactant gas to be supplied to the anodes of MEA 113, as described earlier. Flow fields 112 on anode plate 402 are only routed into face 402a of anode plate 402, they are not drilled through the whole body of the plate through to face 402b. Thus, no flow field is visible on the out faces 402b of the anode plate 402. The outer faces 401b, 402b of plates 401, 402 are also copper plated and are routed with the desired copper design. The holes are drilled or routed through the whole body of the cathode plate 401 as to expose the MEA 113 below the plate to the open atmosphere when the fuel cell board is laminated. Multiple holes can be seen drilled into the PCB. This creates multiple open spaces, channels or flow fields in the plate 401, which will expose the cathode below in the MEA 113 to the oxidant fluid directed over the cathode plate 401, delivering the oxidant fluid to the cathodes. Areas not drilled (herein "land") make electrical contact with the cathodes below, providing an electrically conductive path from the cathode. Anode manifolds 109 are also visible in FIG. 22 and are drilled or routed into the plates after lamination. In this embodiment there is no cathode manifold because reactant air is supplied to the cathodes in a manner described later - via spacers. In this embodiment there is also no coolant manifold, because the anode plate is cooled with an anode spacer, as described later. This simplifies the design and allows more variety in the design of anode manifold and anode reactant distribution throughout a fuel cell stack. After lamination, the outer surface 402b of the anode plate 402 has holes drilled or routed to provide access into the flow fields 112 for the reactant fluid to be supplied from the anode manifold 109 and back into the manifold 109, to and from the flow field 112. The plates also have holes 115 drilled or routed for bolting holes, and / or alignment pins can be inserted into these. Only one of the eight in FIG. 22 is labelled, on plate 402. Cathode plate 401 has a cap layer laminated over the top of the plate, not actually visible or distinguishable from the cathode plate 401 in the Figures. The top and bottom of the cap layer have copper features etched into the surface but are otherwise featureless. The cathode cap layer can be a thin layer of PCB or other such insulating material, which seals the cathode after MEA lamination in the PCB. The MEA needs to be sealed because there is a post-processing step for these fuel cell plates requires plated through holes to be plated through the module. The plated through holes are described later, but are achieved with a dip process in a copper solution which the MEA cannot be exposed to. Once the plated through holes are made, the cap layer can then be routed to expose the open cathode below it. A passivating ink can also be screen printed overflow field surfaces. Generally, there are multiple designs of this open cathode plate that are appropriate, the drilling or routing through the whole body of the plate to create the flow fields or channels could be in any pattern or design which exposes the MEA below. In order to conduct electrons away from the cathode, there must be some "land" or contact with the MEA in multiple places below. The more exposed to reactant air the MEA is, the more reaction can take place at the MEA. However, if there were too many channels or the MEA was too open, then there would be too little contact with the cathodes and a lack of compression of the MEA with a potentially poor electrical conduction away from the MEA. In embodiments herein, a minimum of 40% of the surface area of the open cathode plate can be open or channels, a minimum of 50% of the surface area of the open cathode plate can be open or channels, or minimum of 60% of the surface area of the open cathode plate can be open or channels. The ratio of flow channel (i.e. open insulating material plate, holes) to land or plate which contacts the MEA can be between 40:60 (40 / 60) and 60:40 (60 / 40). Preferably, the channel to land split for a cathode is 60:40 (or 60 / 40). A minimum of 100 individual holes or channels can be provided on a cathode plate to create a minimum of 100 channels, flow field, or access points for reactant to pass through the cathode plate, or in some embodiments a minimum of 200 channels are provided, or a minimum of 400 channels are provided, or a minimum of 600 channels are provide, or a minimum of 800 channels are provide, or a minimum of 1000 channels are provide, or a minimum of 1200 channels are provided. Using drilled holes through the whole body of the plate means that the open cathode plates are easily, quickly and cheaply manufacturable and having at least 40 % to 60 % open area allows for a high reaction rate at the cathodes without compromising the compression of the land on to the cathode. FIG. 23 shows how the plated through holes 120 form an electrical connection between adjacent cathode and anodes in the same board. Each anode is in electrical contact with the next cathode without shorting any cells. FIG. 24 shows a schematic of a fuel cell stack of this embodiment. Four fuel cell boards 4000 are shown. Cathode plates 401 and anode plates 402 are not shown in FIG. 14 but one of each is present in each fuel cell board 4000 as described above. In FIG. 24 three spacers 20 can be seen disposed between the four fuel cell boards 200. These would be two anode spacers and one cathode spacer, and their structure and the function is described herein. Anodes 2 and cathodes 3 are shown, three of each are labelled in FIG. 24, each fuel cell board 4000 has 11 anodes 2 and 11 cathodes 3 arranged in horizontal planes of only anodes 2 and only cathodes 3 in each horizontal plane. Anodes 2 are disposed opposite cathodes 3, with a single electrolyte membrane la between all anodes 2 and cathodes 3 of a single board 200. This layout of the anodes and cathodes in this embodiment is unlike that of a traditional fuel cell, 11 cells are created in each fuel cell board 4000, because of the connection formed between caused by the plated through holes 120. Further, here, no bipolar plate made with electrically conductive materials such as graphite or metals is found between fuel cell boards 4000. Instead, spacers 20 are found between boards. Here, spacers 20 create electrical paths between adjacent boards. As visible in FIG. 24, the spacers 20 are conductive on one side only, the conductive part of the spacer is highlighted 23. The spacers are copper plated along their edge. In these embodiments the current will "zigzag" up / down and across a stack of multiple fuel cell boards 4000 in order to put all the cells in series. This open cathode design has 11 cells in series in a planar arrangement, thus only one side needs to be conductive. The cathode spacers act in place of the coolant plates 300 of the earlier described embodiments, as they can direct a coolant airflow around these stacks. Their design and functions are described in more detail later on. FIG. 25 shows a simplified construction schematic of a board of the present embodiment in the earlier described embodiments, fuel cell boards 4000 are constructed by layering up of an MEAs, insulating material layers and prepreg. In construction of a fuel cell board 4000 of this embodiment, the MEA 1113 is sandwiched between two layers of prepreg 9000, then the cathode and anode plates 4101, 4012. Another layer of prepreg 9000 is then located between the cap layer 4103 and the cathode plate 4101. These layers are laminated together. Plated through holes are drilled into the boards 4000 after they have been laminated together. After this is complete the final drills and routes expose the anode flow fields and cathode flow fields as well as drills for gas manifolding, bolting holes, and alignment pins are made. Once fuel cell boards 4000 of this embodiment are constructed, they can be made into fuel cell stacks. These are modular and made of three main insulating layer components, the fuel cell boards 4000, the anode spacers and the cathode spacers, detailed later. Stacks begin and terminate with an endplate which directs air around the final modules in a stack. After the end plate, the stacking sequence is firstly cathode spacer with gaskets, then fuel cell board 400 with the cathode plate 402 face down, then an anode spacer with gaskets, then another module 400 with the cathode plate 402 face up. This sequence can be repeated indefinitely, terminating on either type of spacer, on top of a second end plate is placed. As described above, the spacers are conductive on one side only, so the current zigzags across the stack in order to put all the cells in series. The stack is held together with bolts, which also compresses the seals between modules in place. The stacks shown throughout are held together with bolts which also provide compression for the seals between modules, however any means to hold stacks together compressed, and end plate types known in the art, may be utilised. The advantages of using spacers and the ability to seal the fuel cell stacks is described above. In conventional fuel cells the current flows in a direction perpendicular to the plane of a fuel cell board, from the anode of one fuel cell board to the cathode of a next adjacent fuel board enabled by bi-polar plates or coolant plates disposed between adjacent fuel cell boards. As such, the fuel cell boards are stacked with the anodes of one fuel cell board facing the cathodes of an adjacent fuel cell board in an anode-cathode-anode-cathode configuration. However, in the present embodiments (e.g. those described in FIG.s 22 to 25), electrical current flows in a direction along the plane of a fuel cell board enabled by the through-membrane electrical connections. There is, therefore, no requirement for direct electrical contact between the fuel cell boards of a stack. As such, the fuel cell boards are stacked such that adjacent fuel cell boards have their anode sides (or cathode sides) facing or opposing each other in an anode-anode-cathode-cathode configuration. A coolant fluid flow is often required to remove excess heat from within a fuel cell stack, while an oxidant reactant fluid flow is required at the cathodes to maintain reactions. When fuel cell boards are stacked in an anode-cathode-anode-cathode configuration, a coolant fluid flow can only be circulated in combination with a reactant fluid flow, as both anodes and cathodes would lie in the space between two adjacent fuel cell boards. However, fuel cells require moisture and humidity to enable good conductivity of ionic pathways to allow them to operate efficiently. A large coolant fluid flow rates removes much of the moisture produced by the reactions in the fuel cell, which reduces fuel cell efficiency and impact the performance of the fuel cell. In the present embodiments, an anode-anode-cathode-cathode configuration (see FIG. 24) enables the coolant and reactant fluid flow to be decoupled in a fuel cell. The configuration enables alternating gaps between the anodes of two adjacent fuel cell boards and the cathodes of two adjacent fuel cell boards. As such, coolant fluid can be directed only to the gaps between anodes and reactant fluid can be directed to the gaps between cathodes. In a compressed fuel cell of the embodiments described here, the gaps between the two anode plates of two adjacent fuel cell boards and between the two cathode plates of two adjacent fuel cell boards in these embodiments are maintained by the spacers mentioned above and described herein. In these arrangements, the coolant fluid and the reactant fluid that flow through each of the alternating gaps can be supplied perpendicular to one another, which further decouples the effects of the coolant and reactant fluid on the fuel cell. This allows fluid to be supplied from two directions (x and y). Thus, according to these embodiments, a coolant fluid flow can be supplied to the anodes in the y-direction to maintain a desired fuel cell temperature, while a reactant fluid flow can be supplied separately to the cathodes in the x-direction to maintain the reaction in the fuel cell. In doing so, the coolant fluid can be supplied at a much higher flow rate than that of the reactant fluid, such that excess heat can be removed effectively while retaining humidity around the cathodes at a desired level to maintain fuel cell efficiency. Moreover, the present arrangement is able to reduce the parasitic power requirement for the fuel cell system in a variety of operating conditions. For example, in hot conditions, the cooling requirement is lowered by the enhanced retention of water on the cathodes. FIG. 26 shows a possible electron pathway in a segmented active area of a fuel cell board. This shows how MEAs can be connected in series across a fuel cell board 70. Such PTHs could not be used when MEAs are connected in parallel. Fuel cell board 70 has two MEAs shown, each with an anode 72 and a cathode 74. Each fuel cell board can have multiple MEAs connected in this manner, this just shows two of a possible multiple. Anodes 72 and cathodes 74 sandwich ion permeable membranes 71. Arrow 76 shows the path of current laterally across the fuel cell board 70. The current first flows from the anode 72 to the copper plating 76 on the upper surface of the board 70 via the plated through holes 80. The current flows across the copper layer 76 on the upper surface of the board, down the plated through hole 82 and along the copper layer 76 on the lower surface of the board. The electrons will then flow through the plated through holes 80 to the cathode 74 on the right side of the board. Four plated through holes 80 are labelled for each MEA, two each side of ion permeable membrane 71. 11 plated through holes 80 are shown for each MEA. FIG. 26 demonstrates how current can flow laterally across a fuel cell board when the MEAs are segmented, as described herein. These MEAs are in series with each other. FIG. 26 demonstrates two types of plated through holes - labelled 80 and 82. Firstly plated through holes 80 which only go pass through (and provide a current pathway through) part of or one layer of insulating material, from one surface of the fuel cell board to the anodes or cathodes. These are labelled 80 In FIG. 5. Secondly plated through holes 82, those which pass through (and provide a current pathway through) the whole fuel cell board, from one surface of the fuel cell board all the way through to the other surface of the fuel cell board. This will be through the at least two insulting layers of insulating material, both the anode and cathode plate. In some arrangements (not shown here), these may go through anodes, cathodes and the ion permeable membranes of MEAs. These are labelled 82 In FIG. 26. FIG. 27a and FIG. 27b show a fuel cell 80-1 from two different perspectives according to an embodiment, an exemplary 4-module stack. The fuel cell stack is encased in a fuel cell casing with end plate 31 shown. Present in this embodiment are three cathode spacers (one of which is labelled 93 in FIG. 27a), two anode spacers (one of which is labelled 95 in FIG. 27b) and four fuel cell boards 400. Slots 86a, 86b, 88a, 88b in the spacers for air are described shortly. Reactant air and coolant air is supplied via gaps in the stack created by the use of. Multiple electrical connection points 46 are visible. 'Slot' is used herein to describe an inlet or an outlet in a fuel cell or a fuel cell board. This has an anode-anode-cathode-cathode 4-module stack configuration with two slots for inlet of cooling air flow and three slots for inlet of reactant air. 5 air inlet / outlet slots 42, 44 are shown for exit of coolant and reactant air, anode slots 42 and cathode slots 44. Each module comprises 11 fuel cell boards, making a 44-cell-stack fuel cell. The fuel cell comprises a reactant fan for directing reactant air flow and a coolant fan for directing coolant air flow (fans not shown). This embodiment has a 'T-Flow' air flow design. Fans can be used in these embodiments as opposed to the air compressors described for the earlier embodiments, because these embodiments do not need as high air pressure, the energy density is lower than that of the earlier embodiments. Fans act as less of an energy parasitic on the system than an air compressor is. In the present embodiment, the reactant air flow and the coolant air flow are also decoupled, but here arranged such that the reactant air flow is in the opposite entry direction to the coolant air flow. In this embodiment, both the reactant air flow and the coolant air flow enter the stack through inlet slots from opposite sides of the stack. Here, this air enters the two long sides of the stack, but each one from a directly opposite side (here both long sides). The coolant air enters the fuel cell stack through the two slots 88a and the reactant air enters the fuel cell through the three slots 88b. Coolant air flows into the stack so that it only reaches the exposed sides of anodes and the reactant air flows into the stack only so that it reaches the exposed sides of cathodes. In this embodiment, both the reactant air flow and the coolant air flow leave the stack from the short sides of the stacks. In this embodiment, the air flow (for both coolant and reactant air) leaves from a side / in a direction substantially perpendicular to how it entered. Here the reactant air flow exits the fuel cell through slots 86a and the coolant air flow exits the fuel cell through slots 86b (dashed line). Slots 86a and 86b alternate with each other through the stack. A single slot or entry point for cooling or reactant fluid can serve multiple layers flow can enter one slot or entry point and can flow through upwards or downwards to multiple layers. In these spacers 93, 95 and other spacers described herein, the copper plating is only on the edges of the spacers, with only one side having conduction between faces. The spacers in the open cathode stacks e.g. cathode spacer 93 are conductive on one side only, the conductive part of the spacer is highlighted 23 in FIG. 24. The spacers are copper plated only along their edge. In these embodiments the current will "zigzag" up / down and across a stack of multiple fuel cell boards 400 in order to put all the cells in series. Anode spacers 95 are conductive (i.e. have plated through holes) on the opposite side of the spacer to the side which is conductive of the cathode spacer 93. If copper was plated anywhere else on a spacer, an electrical short between adjacent cells on a module may occur. The copper on the non-conductive side is present such that one side of the spacer isn't thicker than the other. This enables an even compression over the seals which are only present on the sides of the module. The gaskets that sit in the spacers that seal between adjacent modules are all in the corners of the stack. By adding the copper on the short edge of the spacer, the thickness at this point throughout the stack is the same. Airflow may enter and leave the fuel cell stack in various different flow paths, such as the as described in WO2022 / 106818, which is incorporated herein by reference. The T-shaped flow paths, U-shaped flow paths or flow paths as shown in Figures 21 and 22 of WO2022 / 106818. In embodiments herein, the fluid path or plurality of fluid paths may be arranged to direct the oxidant fluid into the fuel cell board in a direction substantially opposite to the direction in which the fluid path or multiple fluid paths direct the coolant fluid into the fuel cell board, the fluid path or multiple fluid paths may be are arranged so that after input of the coolant fluid into the fuel cell board the coolant fluid leaves the fuel cell board in at least one direction substantially perpendicular to the direction it was directed into the fuel cell board, and the fluid paths may be arranged so that after input of the oxidant fluid into the fuel cell board the oxidant fluid leaves the fuel cell board in at least one direction substantially perpendicular to the direction it was directed into the fuel cell board. The fluid path or multiple fluid paths may also be arranged so that after input of the coolant fluid to the fuel cell board the coolant fluid leaves the fuel cell board in two different directions, both directions substantially perpendicular to the direction the coolant fluid was directed into the fuel cell board, and the fluid path or multiple fluid paths may also be arranged so that after input of the oxidant fluid to the fuel cell board the oxidant fluid leaves the fuel cell board in two different directions, both directions substantially perpendicular to the direction the oxidant fluid was directed into the fuel cell board. The plurality of fluid paths may be arranged to direct the oxidant fluid into the fuel cell board in a direction substantially opposite to the direction in which the fluid path or multiple fluid paths direct the coolant fluid into the fuel cell board, the fluid path or multiple fluid paths may be arranged so that after input of the coolant fluid into the fuel cell board the coolant fluid leaves the fuel cell board in at least one direction substantially opposite to the direction it was directed into the fuel cell board, and the fluid paths or multiple fluid paths may be arranged so that after input of the oxidant fluid into the fuel cell board the oxidant fluid leaves the fuel cell board in at least one direction substantially opposite to the direction it was directed into the fuel cell board. When multiple spacers are present in a fuel cell stack, each spacer may have different fluid paths, different sized, shaped or dimensioned fluid paths or be designed to carry different fluids, or they may have fluids at different flow rates or different fluid temperatures. Multiple anode or multiple cathode spacers could be different from each other, as well as anode and cathode spacers being different from each other. This can address varying coolant or reactant need throughout a fuel cell. Herein the construction of the fuel cell boards and the fuel cell stack is described herein in terms of 'horizontal' and 'vertical' planes, in accordance with the embodiments illustrated in the Figures. However, these terms are used for clarity only, and are not limiting on the scope of the invention. It will be clear to the reader that the fuel cell boards can be arranged in any plane, not just the horizontal plane. Further, the term 'directly opposite' is not limited to the electrodes being in register. The anode lies on one face of the polymer electrolyte and lies directly opposite a cathode on the opposite face of the same electrolyte membrane layer. Reference herein to "heat exchange fluid", "thermal management fluid" or a "temperature control fluid", interchangeable herein, refers to a fluid which can be used in a fuel cell or a component for a fuel cell or other such electrochemical device which can flow near or flow adjacent or flow to contact one or more portions of the fuel cell boards, fuel cells, components for fuel cells or fuel cell stacks described herein. For example, the systems and methods herein can allow a heat exchange fluid to flow through a flow path adjacent or near the anodes of a fuel cell board, acting to cool or heat those anodes. These can act to cool components, for example cool anodes of a fuel cell whilst the fuel cell functions. Or, such heat exchange fluids can act to heat or warm components, for example to heat up an anode component of a fuel cell at the point of fuel cell start up, early in a fuel cell operation timeline / program or in low temperature environments. Heat exchange fluids can be liquids, gases or other such suitable fluids as described herein. Heat or temperature can be added or removed from various parts of the fuel cell boards, fuel cells, components for fuel cells or fuel cell stacks described herein. The heat exchange fluid may contact one or more portions of the fuel cell boards, fuel cells, components for fuel cells or fuel cell stacks described herein. For example, the systems and methods herein can allow a heat exchange fluid to flow through a flow path adjacent or near the anodes of a fuel cell board, acting to cool those anodes. Reference herein to heat transfer or heat conduction may mean heat is directly or indirectly, actively or passively, moved within the context of how it is described. Heat may refer to heat, temperature or thermal energy. Heat may be transferred away from or towards a MEA, or a wider fuel cell board or component of a fuel cell or fuel cell board. Heat may be transferred to Thermal management or heat exchange may be to maintain the fuel cell board or stack at a certain operating temperature, to operate the system in a more energy efficient manner, to increase the operating lifetime of the system, and / or to provide more efficient fuel cell operation (e.g. allowing a fuel cell to operate within set parameters, not leading to over production or under production of power). All heat exchange fluids known to those of skill in the art would be suitable for the purposes of thermally managing or controlling the temperature of fuel cell boards, fuel cells, components for fuel cells or fuel cell stacks described herein. Particularly, heat exchange fluids can be deionised water, water, or a mixture of water or deionised water and glycol to prevent freezing of the water can be used. Other suitable heat exchange fluids are envisioned, and would be known to a person of skill in the art. For example, a fluid with a ratio of 1:1 deionised water to glycol (such as ethylene glycol or propylene glycol) may be used, or alternatively a ratio of 2:1 deionised water to glycol, or alternatively a ratio of 3:1 deionised water to glycol, or alternatively a ratio of 4:1 deionised water to glycol, or alternatively a ratio of 5:1 deionised water to glycol. A solution may be up to 10% glycol in deionised water, or 1% glycol in deionised water, or 2% glycol in deionised water, or 5% glycol in deionised water, or 10% glycol in deionised water, or 20% glycol in deionised water, or 30% glycol in deionised water, or 40% glycol in deionised water, or 50% glycol in deionised water. Or, a heat exchange fluid may be a mixture of another type of alcohol (for example, methanol, ethanol, isopropyl alcohol) and deionised water. A solution may be up to 10% alcohol in deionised water, or 1% alcohol in deionised water, or 2% alcohol in deionised water, or 5% alcohol in deionised water, or 10% alcohol in deionised water, or 20% alcohol in deionised water, or 30% alcohol in deionised water, or 40% alcohol in deionised water, or 50% alcohol in deionised water. Coolant fluid may also comprise one or more perfluoroamines, such as Fluorinert™. Any water described as deionised throughout may also cover non-deionised water, and vice versa. Insulating layers, within a single insulating layer, could have multiple different fluid paths, or channels, of different sizes, shapes and / or dimensions, or fluids at different flow rates or different fluid temperatures. Fluids could be at different temperatures or different flow rates in different plates, or at different temperatures or at different flow rates in different flow paths within the same plate. When multiple thermal management plates are present in a fuel cell stack, each plate may have different fluid paths, different sized, shaped or dimensioned fluid paths or be designed to carry different fluids. Different plates could carry different temperature fluids, or fluids with different flow rates, depending on varying thermal management fluid need throughout the stack. The reactant fluid may be oxygen gas, air or pressurised air or any other suitable fluid which would react at the cathodes. As described above, the reactant fluid for the cathodes may be air draw in from the atmosphere outside the fuel cell by means of a fan or air compression device. Reference herein to "fuel cell boards" or a "fuel cell board" refers to a membrane electrode assembly (MEA) 113 sandwiched between and a cathode plate 101 and an anode plate 102. In the present embodiments, the three layers are laminated together. Some fuel cell boards may have a further or a cap layer 150 also as part of the laminated structure. Fuel cell boards may also be referred to as fuel cell modules herein. The use of'fuel cell board' is not intended to limit the size, shape or arrangement of the MEA, or other components of the board. Fuel cell board is not intended to be limiting on the size, shape or dimensions of the board, it is just a term in the art to refer to the MEAs and plates described herein. The fuel cells, fuel cell boards and components may be constructed of insulating layers, for example Printed Circuit Boards (PCB). Individual layers can be adhered together into a solid structure using an epoxy-containing glass fibre composite ("prepeg"). The MEAs may be laser bonded onto an insulating layer and then to create the fuel cell board, a plurality of boards are laminated together. The gaps between the electrodes, and the sealing achieved in these gaps by the epoxy resin, prevent separate flows from mixing, i.e. prevent air cooling, reactant and fuel flows from mixing. A simple PCB can also be used as the end board or plates in the stacks described herein. The insulating layers of the embodiments herein can be printed circuit boards (PCBs). PCBs for the embodiments may be produced in the known way. Reference herein to 'Printed Circuit Board(s)' or 'PCB(s)' refers to a layer of insulating material comprise of one or more dielectric substrates such as an epoxy resin, for example FR-1, FR-2, FR-3, FR-4, FR-5, FR-6, CEM-1, CEM-2, CEM-3, CEM-4, CEM-5, polytetrafluoroethylene, and G-10, preferably the insulating layer comprises FR-4, which may be laminated together with an epoxy resin prepreg. Plates or boards may comprise one or more layers of these insulating materials. In order to yield conductive areas, a thin layer of a conducting material (for example a metal, for example copper) may either be deposited, plated or applied to the whole insulating substrate and etched away (for example using a mask) to give a desired conductive pattern. Conductive material may be applied by electroplating. The PCBs described throughout may or may not be copper plated in various parts across the PCB boards. Reference herein to a passivating ink may refer to a conductive ink, particularly the ink may have a functional conductive element that is carbon based. The ink acts to provide a low through-plane resistance conductive path between the electrode and the current collector while protecting the copper from the corrosive environment of the fuel cell. It does this by passivating any migratory copper which would otherwise cause irreversible damage of the electrolyte / membrane. Further, the ink may be a carbon ink, it may be a silver paste and polyurethane based ink with conductive elements dispersed in it such as carbon nanotubes or gold / silver nanoparticles these and other inks will be known to a person of skill in the art. It will be appreciated that aspects of the invention can be interchanged or juxtaposed as appropriate. The fuel used is not restricted to hydrogen, but may be any suitable fuel. For example, the new geometry fuel cell stack described herein is also applicable to methanol used in Direct Methanol fuel cells. Other fuel cell types would be known in the art and can use the arrangements and components as described herein, they are not limited to hydrogen fuel cells. Although the invention as exemplified uses hydrogen as the reactant fuel (i.e. the reductant gas for the anodes), the fuel cells could be used with all suitable pressurised fluids. As used herein "fluid" refers to a substance that has no fixed shape and yields easily to external pressure, for example a gas or a liquid. Fuels for use with the systems and methods as described herein are fluids. These fuels can be hydrogen or a hydrogen-containing mixture, or a hydrocarbon or hydrocarbon derivative. Fuels could be other gaseous fuels, such as methane or propane. Fuels could be other gaseous fuels, such as methane or propane and fluids include oxidants such as air and oxygen. The fuel cells and fuel cell boards described herein can be capable of, any envisioned power output for a fuel cell stack. Each fuel cell board may have a power rating of at least 10W. Each fuel cell board may have a power rating of up to 1000W. Each fuel cell board may have a power rating of 10W to 1000W. A fuel cell comprising multiple fuel cell boards may have a power rating of at least 20W. Preferably, each fuel cell comprising multiple fuel cell boards may have a power rating of up to lOOOkW. Preferably, each fuel cell comprising multiple fuel cell boards may have a power rating of 20W to lOOOkW. But, any power rating is merely representative of current embodiments, and the rating may vary from these described as just exemplary. The systems and methods can be used with pressurised fuel storage units or containers, as are well known in the art. The fuel can be stored in a pressurised storage unit, for example a bottle or canister. These can be, for example at a pressure of between 700 and 300 bar. The systems and methods can be used with pressurised fuel storage units or containers, as are well known in the art. The fuel can be stored in a pressurised storage unit, for example a bottle or canister. These can be, for example at a pressure of between 700 and 10 bar. In particular the fuel storage units can be suitable for use with fuel cells as described herein, i.e. at a pressure of between 150 and 350 bar. It will be clear to one skilled in the art that many improvements and modifications can be made to the foregoing exemplary embodiments without departing from the scope of the present disclosure.

Claims

1. A fuel cell board comprising:at least one insulating layer;at least membrane electrode assembly (MEA), the MEA comprising an ion permeable membrane and at least one anode and at least one cathode, wherein each or all cathodes are arranged across a first surface of the ion permeable membrane and each or all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane;wherein the fuel cell board comprises heat conductive means in or on the insulating layer to direct heat towards or away from the MEA.

2. The fuel cell board of claim 1, wherein the heat conductive means comprises means to conduct heat parallel to the MEA along the fuel cell board, horizontally along at least part of the at least one insulating layer.

3. The fuel cell board of claim 1 or claim 2, wherein the heat conductive means comprises conductive material located on a surface of the at least one insulating layer, this surface of the at least one insulating layer facing the MEA of the fuel cell board, wherein the conductive material located on a surface of the at least one insulating layer is connected to heat conductive vias, provided orthogonal to the MEA through at least part of the at least one insulating layer, wherein the conductive material and heat conductive vias are capable of transferring thermal energy away from the MEA.

4. The fuel cell board of claim 3, wherein the heat conductive vias are selected from the group consisting of through holes, buried vias, blind vias or any combination of these, optionally wherein the holes or vias are plated or filled with a conductive material.

5. The fuel cell board of claim 4, wherein the heat conductive vias have a diameter of 100pm to 5mm, preferably between 125 pm and 2mm, preferably between 150 pm and 1mm, preferably between 200 pm and 700 pm, preferably around 300 pm.

6. The fuel cell board of claim 4 and 5, wherein the heat conductive vias have a diameter of at least 150 |jm.

7. The fuel cell board of any one of claims 4 to 6, wherein the heat conductive vias have a diameter less than 3mm.

8. The fuel cell board of any one of claims 3 to 7, wherein more heat conductive vias are located in one or more of the following:i) areas of the fuel cell board which experience a higher temperature in fuel cell operation than those areas of the fuel cell board which experience a lower temperature in operation;ii) areas of the fuel cell board which require cooling;iii) areas of the fuel cell board experiencing a greater exotherm from the electrochemical reaction in operation;iv) sections of the flow-field where at least one of the reactant-flows is hotter;v) in areas where anode and cathode flow fields are adjacent or closer to each other or cross over;v) areas of the fuel cell board with a lower water concentration.

9. The fuel cell board of any one of claims 3 to 8, wherein the density of heat conductive vias is preferably between 5 PTH per cm2 and 20 PTH per cm2, preferably between 7 PTH per cm2 and 18 PTH per cm2, preferably between 9 PTH per cm2 and 15 PTH per cm2, preferably about 11 PTH per cm2.

10. The fuel cell board of any preceding claim, wherein the heat conductive means transfers heat to a means to absorb or dissipate heat, optionally wherein the means to absorb or dissipate heat is a thermal management fluid, coolant fluid, heat sink, a vent to outside the fuel cell, a heat spreader, a heat pipe, another fuel cell board in the fuel cell, a vent or an opening in the fuel cell housing, or any combination thereof.

11. The fuel cell board of any preceding claim, wherein the heat conductive means is one or more means to direct heat towards the MEA,wherein the heat conductive means comprise one or more heat traces to conduct heat parallel to the MEA along the fuel cell board, wherein the heat traces are capable of transferring thermal energy to the MEA.

12. The fuel cell board of claim 11, wherein the one or more heat traces are located inside or on the first insulating layer, and / or wherein the one or more heat traces are located inside or on a further insulating layer, and / or wherein the one or more heat traces are located between the first insulating layer and a further insulating layer, and / or wherein the one or more heat traces are located between two or more further insulating layers.

13. The fuel cell board of claim 11 or claim 12, wherein the one or more heat traces are connected to means to conduct heat from the at least one insulating layer to a further insulating layer,wherein the means to conduct heat from the at least one insulating layer to a further insulating layer comprise one or more of heat conductive vias or an edge of plate connection to a further insulating layer,wherein the heat conductive vias are, provided orthogonal to the MEA through the at least one insulating layer and / or through one or more of the further insulating layers, wherein the conductive material and through vias are for transferring thermal energy to the heat traces, wherein the heat conductive vias connected to the heat traces do not conduct electrical current away from or towards the MEA,wherein the edge of plate connection to a further insulating layer comprises a plating of metallic material around the end of the first insulating layers.

14. The fuel cell board of any one of claims 11 to 13, wherein the heat traces are tracks of heat conductive material.

15. The fuel cell board of any one of claims 11 to 14, wherein the heat conductive means is connected to a means to transfer heat or energy capable ofgenerating heat to the fuel cell board, optionally wherein the means to transfer heat to the fuel cell board is a source of electrical energy, optionally a battery or the fuel cell itself.

16. The fuel cell board of any preceding claim, wherein the heat conductive means, means to conduct heat parallel to the MEA along the fuel cell board and / or the heat conductive vias comprise a conductive material, optionally wherein the conductive material is copper, nickel, a copper alloy, a nickel alloy, graphite or an ink.

17. The fuel cell board of any of the preceding claims, wherein the fuel cell board comprises a second insulating layer and wherein the first insulating layer comprises at least one first fluid path, wherein the first insulating layer is adjacent the anode side of the MEA,wherein the second insulating layer comprises at least one second fluid path, wherein the second insulating layer is adjacent the cathode side of the MEA.

18. The fuel cell board of claim 17 or 18, wherein the MEA, the first insulating layer and the second insulating layer are laminated together to form the fuel cell board.

19. The fuel cell board of any preceding claim, wherein the at least one insulating layer is a printed circuit board (PCB), optionally wherein any other further insulating layers are also PCBs.

20. A fuel cell comprising at least two fuel cell boards of any one of claims 1 to 20.

21. The fuel cell of claim 20, wherein the heat conductive means is different in at least two of the fuel cell boards.

22. The fuel cell of claim 21, wherein:i) one or more of the fuel cell boards closer to the end plates or closer to the peripheral point(s) of the fuel cell stack or further away from the central fuel cell board or further away from the central point of the fuel cell stack compriseheat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards;ii) the two fuel cell boards at the top and bottom of the fuel cell stack or adjacent the fuel cell end plates comprise heat conductive means to direct heat towards the MEA and / or comprise increased heat conductive means to direct heat towards the MEA compared to the other fuel cell boards; and / oriii) one or more of the more central fuel cell boards or those fuel cell boards further away from the fuel cell end plates or the peripheral point(s) of the fuel cell comprise increased heat conductive means in or on the insulating layer(s) to direct heat away from the MEA compared to the other fuel cell boards.

23. The fuel cell of any one of claims 20 to 22, wherein:i) each fuel cell board in the fuel cell is arranged such that the cathodes of each fuel cell board face the anodes of the adjacent fuel cell board and wherein each fuel cell board is arranged such that the anodes of each fuel cell board face the cathodes of the adjacent fuel cell board; orii) each fuel cell board in the fuel cell is arranged such that the cathodes of each fuel cell board face the cathodes of the adjacent fuel cell board and wherein each fuel cell board is arranged such that the anodes of each fuel cell board face the anodes of the adjacent fuel cell board.

24. A method of operating a fuel cell, the method comprising controlling the fuel cell temperature, the fuel cell comprising at least one fuel cell board, the at least one fuel cell board comprising:at least one insulating layer;at least membrane electrode assembly (MEA), the MEA comprising an ion permeable membrane and at least one anode and at least one cathode, wherein each or all cathodes are arranged across a first surface of the ion permeable membrane and each or all anodes are arranged across a second surface opposing the first surface of the ion permeable membrane;wherein the fuel cell board comprises heat conductive means in or on the insulating layer to direct heat towards or away from the MEA,the method comprising transferring heat towards or away from the MEA or the fuel cell board.

25. The method of claim 24, wherein the method comprises transferring heat towards the MEA or the fuel cell board during a fuel cell start-up procedure using the heat conductive means.

26. The method of claim 24 or claim 25, wherein the method comprises transferring heat away from the MEA or fuel cell board during operation of the fuel cell using the heat conductive means.

27. The method of claim 24 to 26, wherein the method comprises transferring heat away from the MEA or fuel cell board during operation of the fuel cell using the heat conductive means bringing the heat in proximity to means to absorb or dissipate the heat, optionally wherein the means to absorb or dissipate heat is a thermal management fluid, coolant fluid, heat sink, a vent to outside the fuel cell, a heat spreader, a heat pipe, another fuel cell board in the fuel cell, a vent or an opening in the fuel cell housing, or any combination thereof.

28. The method of any one of claims 24 to 32, wherein the method comprises transferring heat to or transferring heat from different fuel cell boards or MEAs at a different rate or amount to other fuel cell boards or MEAs in the same fuel cell during fuel cell start up or during fuel cell operation.

29. The method of claim 28, wherein the method comprises transferring heat towards the MEA or a fuel cell board when a fuel cell board is performing at a lower power or operating efficiency than other fuel cell boards in the stack, the method first comprising monitoring the temperature of that fuel cell board.

30. The method of any one of claims 24 to 29, wherein the method comprises monitoring the temperature of at least one or multiple fuel cell boards or MEAs of the fuel cell.Application No: GB2313376.2Claims searched: 1-30Examiner: Dr Fiona RogersDate of search: 18 October 2023Patents Act 1977: Search Report under Section 17Documents considered to be relevant:Category Relevant to claims Identity of document and passage or figure of particular relevance X 1-10, 16-18, 20-21, 23-24, 26-27 and 30 US 2006 / 0141328 Al (JOHNSTON et al.) See in particular abstract, Figure 2 and paragraphs [0057], [0058], [0061] and [0115], X 1-10, 16-18, 20-21, 23-24, 26-27 and 30 US 2011 / 0262829 Al (FLY et al.) See in particular abstract, Figures 2-4B and paragraphs [0028]-[0029], [0034] and [0036], v A 1-10, 16-21, 23-24, 26-27 and 30 WO 2023 / 052789 Al (BRAMBLE ENERGY LTD) See in particular abstract, page 21 lines 4-20, page 27 line 16 to page 28 line 29 and Figures 6a-9. X 1-10, 16-21, 23-24, 26-27 and 30 US 2010 / 0040924 Al (NIROUMAND) See in particular abstract, Figures l-2b and 5 and paragraphs [0034]-[0037], [0040] and [0051], X 1-2, 10, 16-18, 20-21, 23-24, 26-27 and 30 CN 212182459 U (TAO LINMI) See in particular EPODOC abstract, WPI abstract accession no. 2020-04575K and Figures 15-17. X 1-2, 10, 16, 19-21, 23-24, 26-27 and 30 CN 1797827 A (NANYA CIRCUIT BOARD CO LTD) See in particular EPODOC abstract, WPI abstract accession no. 2007-139148 and Figures.Categories:X Document indicating lack of novelty or inventive step A Document indicating technological background and / or state of the art. Y Document indicating lack of inventive step if P Document published on or after the declared priority date but combined with one or more other documents of same category. before the filing date of this invention. & Member of the same patent family E Patent document published on or after, but with priority date earlier than, the filing date of this application.Field of Search:Search of GB, EP, WO &US patent documents classified in the following areas of the UKCX :Worldwide search of patent documents classified in the following areas of the IPC____________HO IM_________________________________________________The following online and other databases have been used in the preparation of this search report SEARCH - PATENTInternational Classification:Subclass Subgroup Valid From HO IM 0008 / 0267 01 / 01 / 2016 HO IM 0008 / 0256 01 / 01 / 2016 HO IM 0008 / 026 01 / 01 / 2016 HO IM 0008 / 04007 01 / 01 / 2016 H01M 0008 / 043 01 / 01 / 2016 HO IM 0008 / 04302 01 / 01 / 2016 HO IM 0008 / 0432 01 / 01 / 2016 HO IM 0008 / 04701 01 / 01 / 2016 HO IM 0008 / 10 01 / 01 / 2016 HO IM 0008 / 241 01 / 01 / 2016

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