Methods and systems for producing hydrogen

Abstract

A method of producing hydrogen by reacting silicon powder and water, comprises providing water in a reactor (120), providing loose silicon powder in the reactor (120), dispersing the silicon powder in the water in the reactor (120), and5 collecting hydrogen gas from the reactor (120). The silicon powder is provided as a plurality of silicon doses, each silicon dose comprising a predetermined amount of the silicon powder. The disclosure provides methods systems and energy carriers which are suitable in the context of production of hydrogen by reacting silicon powder and10 water. (Fig. 1) 15

Description

[0001] METHODS AND SYSTEMS FOR PRODUCING HYDROGEN

[0002] Technical field

[0003] The present disclosure relates to methods and systems for producing hydrogen by reacting silicon powder and water, as well as a energy carriers for use in such methods and systems.

[0004] The disclosure also provides methods of introducing the silicon powder into a reactor.

[0005] The disclosure also provides an energy carrier suitable for thermal energy storage, as well as its use for such thermal energy storage.

[0006] Background

[0007] JPH0459601, US7493765B2, US2016046486A and US2016046487A disclose the general idea of using silicon as an energy carrier, instead of e.g. hydrocarbon based energy carriers. In particular, these documents disclose a system and method for employing silicon as a supplement or replacement for current hydrogen storage techniques. The method may include generating or using energy from an energy source, using this energy to purify and refine silicon to an acceptable level of purity, transporting the purified and refined silicon to a place of use, reacting the purified and refined silicon with water in a particular environment or in a particular system in order to produce hydrogen gas and other products, and storing or directly using the generated hydrogen while optionally recycling the other products.

[0008] In particular, from US2016046486A1, it is known to use silicon nano-powder for such production of hydrogen.

[0009] Methods for producing nano-powder, which are potentially applicable to silicon, are known from e.g. US2497738, KR20040070699, W02004101434, US2001004855A1 and US4900355.

[0010] Handling a nano-powder is challenging, in that it must be prevented from contaminating the atmosphere during transport, storage and handling in a hydrogen production system. Hence, supply, handling, dosage and feeding of the nanopowder needs to be contained in a closed system.

[0011] Hence, there is a need for a method of producing hydrogen by reacting silicon powder with water, which facilitates the handling of the silicon powder.

[0012] It is an objective of the present disclosure to provide methods and systems which alleviate problems with prior art methods and systems for producing hydrogen by reacting silicon powder and water.

[0013] Particular objectives include providing methods and systems which enable efficient and environmentally friendly handling of energy carrier and residual products in such processes.

[0014] The invention is defined by the appended independent claims, with embodiments being set forth in the appended dependent claims, in the following description and in the attached drawings.

[0015] According to a first aspect, there is provided a method of producing hydrogen by reacting silicon powder and water, comprising providing water in a reactor, providing loose silicon powder in the reactor, dispersing the silicon powder in the water in the reactor, and collecting hydrogen gas from the reactor. The method further comprises providing the silicon powder as a plurality of silicon doses, each silicon dose comprising a predetermined amount of the silicon powder.

[0016] The silicon powder may comprise silicon in a proportion of at least 45 % by weight, preferably at least 50 % by weight, at least 60 % by weight, at least 70 % by weight, at least 80 % by weight, at least 90 % by weight, at least 95 % by weight, at least 98 % by weight, at least 99 % by weight or at least 99.5 % by weight.

[0017] The silicon powder may preferably be a nano-powder, i.e. a powder having a particle size of about 1-1000 nm, and in particular of about 1-100 nm and more particularly about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm or about 90-100 nm.

[0018] By providing the nano powder as silicon doses, handling and control of the hydrogen production process is facilitated. Moreover, the division of the silicon powder into silicon doses makes it possible to eliminate the handling of loose silicon powder.

[0019] The method may further comprise continuously or intermittently determining a hydrogen production rate, identifying when the hydrogen production rate drops below a threshold rate, and when the hydrogen production rate drops below the threshold rate, feeding at least one additional silicon dose to the reactor.

[0020] The hydrogen production rate may be a measure indicative of how much hydrogen is currently being produced per unit of time.

[0021] The determining may be achieved by directly measuring, by indirectly measuring or by estimating based on a model and one or more data points.

[0022] In the method, said determining a hydrogen production rate may comprise measuring at least one parameter indicative of the hydrogen production ratio.

[0023] The measuring may be achieved by directly measuring a production by means of pressure or flow of hydrogen gas, or indirectly measuring the production by measuring a pressure or flow of a by-product, or the like.

[0024] In the method, said determining a hydrogen production rate may comprise estimating the hydrogen production ratio based on historical data of the hydrogen production rate and / or based on a prediction model of the hydrogen production rate.

[0025] In the method, each of the silicon doses may be individually encapsulated in an oxygen-reduced space formed by an enclosure.

[0026] The term "oxygen-reduced" implies that the space in which the silicon powder provides an atmosphere having, preferably no free oxygen, but at most an amount of free oxygen which is so small as to have essentially no oxidizing effect on the silicon contained in the space.

[0027] In particular, the amount of oxygen available in the space should be so small as to enable oxidation of less than 5 % of the silicon contained in the space, preferably less than 1 %, less than 0.5 % or less than 0.1 %.

[0028] The oxygen-reduced space may be obtained by at least partial vacuum, or by provision of an inert gas.

[0029] In some embodiments, at least some of the silicon doses may be provided in a respective non-water soluble enclosure, wherein the method further comprises opening the enclosure encapsulating said predetermined amount of silicon powder, so as to release the silicon powder.

[0030] A dose opener may be a device for e.g. piercing, cutting or tearing apart the encapsulation so as to release the silicon powder. The silicon powder contained in the enclosure may be non-cohesive, i.e. loose, such that it is readily dispersed in the water.

[0031] Subsequent to opening the enclosure, gas or liquid may be injected therein in order to assist in driving out the silicon powder, so as to empty the silicon dose.

[0032] Subsequent to said emptying, the enclosure may be compressed, e.g. to take up less space and thus facilitate storage and recycling.

[0033] In some embodiments, at least some of the silicon doses may be provided in a respective water soluble enclosure, wherein the method further comprises feeding said silicon dose to the reactor, such that the water soluble enclosure is dissolved, so as to release the silicon powder.

[0034] Hence, the feed device may feed a silicon dose which is encapsulated by a water soluble enclosure, whereby the enclosure is dissolved when the silicon dose is immersed in the water in or in a reactor feed chamber.

[0035] The silicon powder contained in the enclosure may be non-cohesive, i.e. loose, such that it is readily dispersed in the water.

[0036] In some embodiments, at least some of the silicon doses may be provided as cohesive bodies of the silicon powder, or in the form of silicon pellets or silicon briquettes having larger particle size than the silicon powder. In such embodiments the method may further comprise converting at least some of the cohesive bodies of the silicon powder into loose silicon powder, or converting at least some of said silicon pellets or silicon briquettes having larger particle size than the silicon powder into loose silicon powder, whereby a particle size is reduced.

[0037] The converter may be a device for e.g. grinding, chopping or crushing a cohesive body of silicon powder into loose silicon powder.

[0038] Hence, the silicon powder may be converted into non-cohesive, loose, powder prior to its introduction into the reactor.

[0039] The method may, further comprise receiving a set comprising a plurality of silicon doses, and selectively feeding said at least one of said silicon doses from the set to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

[0040] The set may comprise a cartridge comprising a plurality of silicon doses, and the method may comprise selectively feeding said at least one of said silicon doses from the cartridge to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

[0041] A cartridge may be defined as a cartridge housing, which holds a plurality of silicon doses. In its most simple form, a cartridge may merely hold a plurality of silicon doses, such that they can be individually fed to the reactor. However, the cartridge may be configured such that the silicon doses are held in a specific manner, such as a specific orientation, that facilitates their handling and the extraction of the silicon powder from the silicon dose.

[0042] For example, a cartridge may comprise a dose holder that may be movable so as to advance silicon doses toward a silicon dose opening.

[0043] Optionally, the cartridge may be configured to retain, or receive, dose enclosures, from which the silicon powder has been extracted, such that they can be recycled.

[0044] Cartridge housings may be designed such that they are stackable for facilitating storage and transportation.

[0045] In the method, the set may comprise a web to which the plurality of silicon doses are connected, and wherein the method comprises releasing at least one of said silicon doses from the web and feeding it to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

[0046] When releasing a silicon dose from a web, the silicon dose, this may be achieved by opening an enclosure of the silicon dose, so as to release non-cohesive silicon powder, by releasing the silicon enclosure from the web, so as to allow the silicon enclosure to dissolve when it enters the water; or by releasing a cohesive body of silicon powder, which optionally may be coated, from the web.

[0047] In some embodiments, the method may further comprise providing silicon oxide, reducing the silicon oxide into said silicon, optionally converting the silicon into silicon powder, and dividing said silicon powder into said silicon doses.

[0048] Hence, through e.g. magnesiothermic reduction of silica (i.e. silicon dioxide), in particular silica in powder form, or through electrolysis, there is provided an integrated way of storing non-controllable power, such as solar power or wind power as silicon powder or, ultimately, as hydrogen, for use at a later point in time.

[0049] The method may be performed in a stationary installation. The stationary installation may be selected from a group consisting of a power plant for production of electricity; a single- or multi- family dwelling; an offshore platform; and an industrial facility, wherein the hydrogen is used in a chemical process, such as a direct reduced iron plant.

[0050] The method may be performed in a mobile installation.

[0051] The mobile installation may be selected from a group consisting of a land- based vehicle, such as a train, a construction machine, an agricultural machine or an automobile; a water-based vehicle, such as a ship or a yacht; an air-based vehicle, such as a fixed-wing aircraft or a rotary-wing aircraft, and a space-based vehicle or structure, such as a space shuttle, a satellite or a space station.

[0052] The method may further comprise providing a catalyst to the reactor.

[0053] Non-limiting examples of catalysts include KOH, NaOH, Na2SiO3.

[0054] Each silicon dose may comprise an effective amount of the catalyst.

[0055] The silicon powder may comprise, consist, or consist essentially of, silicon particles, which are provided with a water-soluble coating, configured to delay the particles' reaction with the water.

[0056] According to a second aspect, there is provided a system for producing hydrogen by reacting silicon powder and water, comprising a reactor for reacting the water and the silicon powder, a silicon supply unit for feeding individual doses of the silicon powder, each dose comprising a predetermined amount of the silicon powder, a water supply unit for feeding water to the reactor, a controller, configured to: determine a hydrogen production rate, identify when the hydrogen production rate drops below a threshold rate, and control the silicon supply unit for feeding at least one additional silicon dose when the hydrogen production rate drops below the threshold rate.

[0057] In some embodiments, the system may further comprise a dose opener, configured to open an enclosure encapsulating said predetermined amount of silicon powder, so as to release the silicon powder.

[0058] A dose opener may be a device for e.g. piercing, cutting or tearing apart the encapsulation so as to release the silicon powder.

[0059] In some embodiments, the feed device may be configured to feed a silicon dose into the reactor while the silicon dose is enclosed in an encapsulation. Hence, the feed device may feed a silicon dose which is encapsulated by a water soluble enclosure, whereby the enclosure is dissolved when the silicon dose is immersed in the water in or in a reactor feed chamber.

[0060] In some embodiments, the system may further comprise a dose converter, configured to convert a cohesive body of the silicon powder into loose silicon powder, or convert silicon pellets or silicon briquettes having larger particle size than the silicon powder into loose silicon powder, whereby a particle size is reduced.

[0061] The converter may be a device for e.g. grinding, chopping or crushing a cohesive body of silicon powder into loose silicon powder.

[0062] In the system, the feed device may comprise a dose cartridge handling device, configured to receive a cartridge comprising a plurality of silicon doses, and selectively feed said at least one of said silicon doses from the cartridge to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

[0063] In some embodiments, the system may further comprise a silicon powder production device, configured for producing silicon powder from silicon oxide, the silicon powder production device being directly connected to the feed device.

[0064] According to a third aspect, there is provided an energy carrier, comprising a predetermined amount of silicon powder, the silicon powder having a level of purity of at least 45 % by weight, an enclosure, encapsulating said silicon powder, wherein a space encapsulated by the enclosure is oxygen-reduced.

[0065] When using the term "silicon" absent any further compound, this is to be construed as pure silicon.

[0066] The silicon powder may comprise silicon in a proportion of at least 45 % by weight, preferably at least 50 % by weight, at least 60 % by weight, at least 70 % by weight, at least 80 % by weight, at least 90 % by weight, at least 95 % by weight, at least 98 % by weight, at least 99 % by weight or at least 99.5 % by weight.

[0067] Hence, the silicon powder may correspond to silicon slag, when the silicon is present in a proportion of about 45-70 % by weight. Alternatively, the silicon powder may correspond to ferro silicon when the silicon is present in a proportion of about 65-80 % by weight. Alternatively, the silicon powder may correspond to off-grade silicon when silicon is present in about 97 % by weight. The silicon powder may correspond to metallurgical silicon when the silicon is present in a proportion of more than 98 % by weight. The silicon powder may be essentially non-compressed, in particular noncohesive.

[0068] The silicon powder may be compressed to form a cohesive body.

[0069] The silicon powder may be vacuum-packaged in the enclosure.

[0070] The silicon powder may be contained in an effectively inert atmosphere in the enclosure.

[0071] The enclosure may be non-water soluble.

[0072] Alternatively, the enclosure may be water soluble.

[0073] The predetermined amount may be about 1-500 g.

[0074] In particular, the predetermined amount may be about 1-5 g, about 5-10 g, about 10-50 g, about 50-100 g, about 100-200 g, about 200-300 g, about 300-400 g or about 400-500 g.

[0075] The silicon powder may have a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about GOO nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

[0076] The silicon powder may comprise, consist, or consist essentially of, silicon particles, which are provided with a water-soluble coating, configured to delay the particles' reaction with the water.

[0077] According to a fourth aspect, there is provided a cartridge, comprising a cartridge housing enclosing a plurality of energy carriers as described above.

[0078] The cartridge may be configured to retain or receive emptied enclosures.

[0079] According to a fifth aspect, there is provided a cartridge, comprising a cartridge housing enclosing a plurality of energy carriers, each of which being provided as a cohesive body of silicon powder having a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50- 60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about SOO- GOO nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900- 1000 nm.

[0080] The cartridge may comprise a feed mechanism for causing the energy carriers to move towards an opening in the housing. A feed mechanism may comprise a disc or a conveyor, to which the energy carriers may be attached. The attachment may be permanent or releasable. The feed mechanism may be actuated by an external actuator.

[0081] In the alternative, the feed mechanism may comprise a biasing mechanism, which may be included in the cartridge, whereby the energy carriers may be biased towards the output opening of the housing. ]

[0082] The cartridge housing may present engagement members for engagement with identical cartridge housings to counteract said cartridge housings shifting when arranged as a stack.

[0083] According to a seventh aspect, there is provided an energy carrier assembly, comprising a plurality of energy carriers as defined above and a web, wherein the energy carriers are supported by the web.

[0084] The web may comprise a rigid or flexible material, such as a strip or sheet, to which the energy carriers may be attached. A flexible material may be a film, a woven or a non-woven sheet. Hence, energy carriers may be fed by advancing the web in a feed mechanism. In some embodiments, energy carriers may be released from the web. In other embodiments, enclosures of spent energy carriers may be retained on the web for recycling, optionally in combination with a compression of an energy carrier enclosure to save space.

[0085] According to a seventh aspect, there is provided a method of feeding an energy carrier as defined above, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising opening the enclosure prior to feeding the silicon powder into the water.

[0086] According to a eighth aspect, there is provided a method of feeding an energy carrier as defined above, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising depositing the energy carrier into the water and allowing the enclosure to dissolve so as to release the silicon powder.

[0087] According to an ninth aspect, there is provided a method of feeding an energy carrier in the form of silicon powder, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising providing a body of silicon, converting said silicon into silicon powder, and feeding said silicon powder into the reactor. In particular, the body of silicon may be a cohesive body of silicon powder or a body consisting essentially of silicon having a level of purity of at least 45 % by weight.

[0088] The silicon powder may be a nano powder, in which case the particles need merely to be separated from each other, or it may be a powder having larger particle size, wherein the particles will need to be reduced in size to form a nano powder, e.g. by grinding or crushing.

[0089] The method may further comprise removing or opening an encapsulation from the cohesive body prior to said converting.

[0090] The method may further comprise converting an encapsulation encapsulating the cohesive body during said converting.

[0091] The silicon powder may be provided as, or converted into, silicon powder having a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about SO- O nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

[0092] According to a tenth aspect, there is provided an energy carrier, comprising a cohesive silicon powder body which is formed of a silicon powder, said silicon powder having a level of purity corresponding to about 45 % to less than 95 % by weight silicon and a particle size which is less than about 0.5 mm.

[0093] The silicon may have a particle size of about 1-100 pm, about 100-200 pm, about 200-300 pm, about 300-400 pm or about 400-500 pm.

[0094] The silicon powder may have a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60- 70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

[0095] According to a eleventh aspect, there is provided use of an energy carrier as defined above in a hydrogen production process, comprising converting the silicon powder body into loose powder, and causing said loose powder to react with water to form hydrogen and silicon oxide. According to an twelfth aspect, there is provided use of an energy carrier as defined above in an energy conversion process, comprising converting the silicon powder body into loose powder, and causing said loose powder to undergo a combustion process in the presence of oxygen.

[0096] According to a thirteenth aspect, there is provided an energy carrier, comprising a cohesive body which is formed of silicon particles having a level of purity corresponding to about 45 % to less than 95 % by weight silicon and a particle size of at least about 1-250 mm, about 5-100 mm, about 10-100 mm, about 20-80 mm or about 10-80 mm.

[0097] Such an energy carrier can be used for thermal energy storage.

[0098] The energy carrier body may have a mass of at least about 50 kg, preferably about 50-3000 kg.

[0099] The energy carrier body may have a density near room temperature of less than about 2329 kg / m3.

[0100] According to a fourteenth aspect, there is provided use of an energy carrier as defined above, for accumulating thermal energy, said thermal energy having a temperature greater than 120 degC, preferably greater than 200 degC, greater than 300 degC, greater than 400 degC or greater than 500 degC, and less than about 3265 degC, preferably less than about 2500 degC or less than 1414 degC.

[0101] According to a fifteenth aspect, there is provided a system for producing hydrogen, comprising a reactor for reacting water and silicon powder to produce hydrogen gas, a silicon supply unit connected to the reactor for supplying loose silicon powder to the reactor, a water supply unit connected to the reactor for supplying water to the reactor, a hydrogen dryer unit connected to the reactor for receiving hydrogen gas from the reactor and for supplying dried hydrogen gas, and a controller for controlling at least some of the silicon supply unit, the water supply unit, the reactor, the hydrogen dryer, the hydrogen compressing unit and the hydrogen storage tank.

[0102] The system may further comprise a hydrogen compressing unit connected to the hydrogen dryer for receiving dried hydrogen gas.

[0103] The compressing unit can be used for compressing the hydrogen gas in applications where feeding and / or storage of the hydrogen gas requires an elevated pressure as compared with outgoing pressure from the reactor. However, in some applications it may be possible to use, e.g. a fuel cell at a lower pressure direct from the reactor.

[0104] The system may further comprise a hydrogen storage tank connected to the hydrogen compressing unit for receiving compressed hydrogen gas from the hydrogen compressing unit.

[0105] The system may further comprise a consumer, connectable to the hydrogen compressing unit or to the hydrogen storage tank, for receiving hydrogen gas and for converting the hydrogen gas into thermal, mechanic and / or electric energy from the hydrogen storage tank.The system may further comprise an oxygen compressing unit connected to the reactor for receiving oxygen gas from the reactor and for supplying compressed oxygen gas to an oxygen gas storage tank.

[0106] In the system, the oxygen gas storage tank may be connected to the consumer for supplying oxygen gas to the consumer.

[0107] Hence, the performance of the consumer may be improved.

[0108] In the system, the consumer may comprise a hydrogen fuel cell.

[0109] In the system, the consumer may comprises a hydrogen combustion engine.

[0110] The system may further comprise a consumer water return channel for returning water from the consumer to the water supply unit or to the reactor.

[0111] Optionally, a consumer condenser may be provided at the consumer, for condensing water vapor formed in the consumer, whereby the consumer water return channel may be connected to the consumer condenser, to receive condensed water.

[0112] By including a consumer water return channel, the need for refilling the water supply can be reduced.

[0113] The system may further comprise a hydrogen dryer water return channel for returning water from the hydrogen dryer to the water supply unit or to the reactor.

[0114] The hydrogen dryer may comprise a condenser, for condensing water vapor contained in the gas mixture, and in particular in a hydrogen gas stream from the reactor, whereby the hydrogen dryer water return channel may be connected to the condenser, to receive condensed water.

[0115] By including a hydrogen dryer water return channel, the need for refilling the water supply can be reduced. The system may further comprise a silicon oxide management system comprising a silicon oxide dryer and a silicon oxide water return channel for returning water from the silicon oxide management system to the water supply unit or to the reactor.

[0116] In the system, the silicon supply unit may be configured for feeding individual doses of the silicon powder, each dose comprising a predetermined amount of the silicon powder, and the controller may be configured to determine a hydrogen production rate, identify when the hydrogen production rate drops below a threshold rate, and control the silicon supply unit for feeding at least one additional silicon dose when the hydrogen production rate drops below the threshold rate.

[0117] At least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller may be supported by a mobile platform, in particular a vehicle, vessel or aircraft.

[0118] A mobile platform may be a vehicle, such as an automobile, a lorry / truck, a bus or a construction machine. A mobile platform may also be a tracked vehicle, such as a train, a tram, or the like. Further, a mobile platform may be a water vessel, which may be manned or unmanned, such as a surface vessel or a submarine. Yet further, a mobile platform may be an aircraft, which may be manned or unmanned, such as an airplane or a helicopter.

[0119] In particular, all components of the system including the consumer, may be supported by the mobile platform.

[0120] The consumer may be configured to propel the mobile platform, such that the mobile platform can move relative to its surrounding.

[0121] At least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller may be provided as a fixed construction.

[0122] Hence, the various parts may be provided as a part of a power plant for supplying power to an installation, such as a factory, a service facility or the like.

[0123] At least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller may be provided as a portable unit.

[0124] Hence, the various parts may be provided as a part of a portable device for producing hydrogen for use in e.g. a laboratory setting. According to a sixteenth aspect, there system for converting energy, comprising a reactor for reacting water and silicon powder to produce hydrogen gas, a silicon supply unit connected to the reactor for supplying loose silicon powder to the reactor, a water supply unit connected to the reactor for supplying water to the reactor, a consumer, connectable to the hydrogen compressing unit or to the hydrogen storage tank, for receiving hydrogen gas and for converting the hydrogen gas into thermal, mechanic and / or electric energy, and a consumer water return channel for returning water from the consumer to the water supply unit or to the reactor.

[0125] Fig. 1 is a schematic diagram of a system for producing hydrogen gas.

[0126] Fig. 2 is a schematic diagram of a silicon powder supply unit according to a first embodiment.

[0127] Fig. 3 is a schematic diagram of a silicon dose according to a first embodiment.

[0128] Fig. 4 is a schematic diagram of a silicon powder supply unit according to a second embodiment.

[0129] Fig. 5 is a schematic diagram of a silicon dose according to a second embodiment.

[0130] Fig. 6 is a schematic diagram of a silicon powder supply unit according to a third embodiment.

[0131] Fig. 7 is a schematic diagram of a silicon dose according to a third embodiment.

[0132] Fig. 8 is a schematic diagram of a silicon powder supply unit according to a fourth embodiment.

[0133] Fig. 9 is a schematic diagram of a silicon powder dose cartridge.

[0134] Fig. 10 is a schematic diagram of a system for producing hydrogen gas, which can be applied on a mobile platform.

[0135] Fig. 11 schematically illustrates a hydrogen production system provided as a fixed construction.

[0136] Figs 12a-12d schematically illustrate a silicon powder extraction sequence. Fig. 13 schematically illustrates a cohesive block of silicon particles for storing thermal energy.

[0137] Detailed description

[0138] Fig. 1 schematically illustrates a system for producing hydrogen gas.

[0139] The system comprises a silicon powder supply unit 100 and a water supply unit 110, which are arranged to feed silicon powder and water, respectively, to a reactor 120.

[0140] The silicon powder supply unit 100 is configured to supply silicon powder having a particle size in the range of. In particular, the silicon powder may have a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm, about 900-1000 nm.

[0141] The silicon powder may have a purity corresponding to at least metallurgical silicon, i.e. the silicon powder comprises at least about 95 wt.-% silicon, preferably at least about 98 wt.-% silicon.

[0142] The water supply unit 110 may be configured to supply pure water or water with some content of salts, such as NaCI. The water supply unit 110 may comprise a connection to a pressurized water source, such as a mains water supply, or a container for water. The water supply unit 110 may further comprise one or more controllable valves, filters, pumps, etc. as needed for supplying water to the reactor 120 in a controlled manner and as required.

[0143] The silicon powder supply unit 100 and the water supply unit 110 may be operatively connected to a system controller 600, such that at least outputs from the silicon powder supply unit 100 and the water supply unit 110 to the reactor 120 can be controlled with a sufficient degree of precision.

[0144] Additionally, the reactor 120 may be connected to the controller 600, to be controlled thereby.

[0145] Downstream of the reactor 120, or integrated with the reactor 120, there may be provided a gas separator 130, configured to separate hydrogen and oxygen gas. Oxygen gas may be led to an oxygen management arrangement 400, which may include purification, compression and / or storage functionality, or release to surrounding environment.

[0146] A waste water management system 200 may be connected to the reactor 120, in order handle water taken out from the reactor 120, either continuously, at intervals or ad hoc as needed in response to a measured water quality.

[0147] The waste water management system 200 may thus remove water having too high amounts of contaminants. Such water may be dispensed with or purified, such as filtered, distilled, etc., whereby purified water may be returned to the water supply unit 110.

[0148] Additionally, the waste water management system 200 may be connected to the controller 600, to be controlled thereby.

[0149] A silicon oxide management system 300 may also be connected to the reactor 120 to collect silicon oxide formed in the reactor for deposition or recycling, either continuously, at intervals or ad hoc as needed, in response to e.g. a measured amount of silicon oxide having been formed.

[0150] The silicon oxide management system 300 may receive silicon oxide particles formed in the reactor. Such silicon oxide may be dispensed with. Alternatively, the silicon oxide may be dried, with water being returned to the water supply unit 110.

[0151] Additionally, the silicon oxide management system 300 may be connected to the controller 600, to be controlled thereby.

[0152] Downstream of the gas separator 130, there may be provided a gas dryer unit 140 for removing water and possibly other undesirable substances present in the flow of hydrogen gas from the reactor 120. To this end, the hydrogen gas dryer unit 140 may comprise a condenser 141 and / or a heat exchanger.

[0153] Gas from the gas dryer 140 may optionally be fed to a buffer 150 for intermediate storage of the hydrogen gas.

[0154] Additionally, the gas dryer 140 may be connected to the controller 600, to be controlled thereby.

[0155] The condenser 141 may be arranged for condensing water vapor contained in the gas mixture, and in particular in a hydrogen gas stream from the reactor 120, whereby a hydrogen dryer water return channel may be connected to the condenser 141, to receive condensed water.The gas dryer water return channel may return water to the water supply 110 or directly to the reaction chamber 120.

[0156] From the buffer 150, the hydrogen gas may be compressed by a compressor unit 160 and led to a storage tank 170, where the hydrogen gas can be stored for immediate use or for transfer to a site of use. The hydrogen compressor unit 160 may comprise a compressor, a flow control valve and a pressure gauge, which may be connected in series in said order. An output of the hydrogen compressor unit 160 may be connected to the hydrogen storage tank 170. The compressor, the flow control valve and the pressure gauge may be connected to the controller 600, such that the compressor and flow control unit may be controlled by the controller and such that the pressure gauge may provide data to the controller 600.

[0157] The controller 600 may be connected to the buffer 150, such that the amount of hydrogen present in the buffer 150 can be determined by the controller 600.

[0158] The controller 600 may be connected to the storage tank 170, such that the amount of hydrogen present in the storage tank 170 can be determined by the controller 600.

[0159] Hence a hydrogen consuming device 500 may receive hydrogen gas through a direct line from the buffer 150, the compressor unit 160 or storage tank 170.

[0160] Alternatively, the hydrogen gas may be stored in transfer tanks, which may be physically moved to the hydrogen consuming device 500.

[0161] The hydrogen consuming device 500 may be an industrial process employing hydrogen gas, such as a direct reduction iron process.

[0162] Alternatively, the hydrogen consuming device 500 may include a fuel cell arrangement, configured to generate electricity from hydrogen gas.

[0163] The fuel cell arrangement may be provided in a fixed structure, such as a building or a process plant, or in a movable structure, such as a vehicle.

[0164] In cases where the fuel cell arrangement is provided in the same site, or movable structure, as the reactor, a water recycling device may be provided for recycling water from the fuel cell to e.g. the reactor.

[0165] Additionally, the hydrogen consuming device 500 may be connected to the controller 600, to be controlled thereby. In particular, the hydrogen consuming device 500 may indicate the need for an increase or decrease in the production of hydrogen, such that one or more parts of the system may be adjusted in response.

[0166] Referring to fig. 2, there is illustrated a schematic diagram of a silicon powder supply unit 100 according to a first embodiment, wherein the silicon powder supply unit is configured to receive a cartridge 1 holding a plurality of silicon doses 10a, 10b, 10c, lOd, lOe, .., lOn in a cartridge receptacle 101.

[0167] The cartridge receptacle 101 may be configured to connect with the cartridge 1 such that silicon doses can be extracted from the cartridge 1 and supplied to a dose opener 102 for opening each dose and providing the corresponding silicon powder to a dose feeder 103 that feeds the loose silicon powder 15' to the reactor 120.

[0168] The hydrogen storage 170 may be fixedly connected to the system, or it may be formed by one or more units, such as tanks, which can be swapped, transported to a site where the hydrogen is to be used, recycled and then refilled.

[0169] The silicon powder supply unit 100 may be configured to output used dose enclosures, e.g. for recycling.

[0170] In variants of this embodiment, the opener may be included in the cartridge 1, and / or the doses may be opened while they remain in the cartridge 1, such that only the silicon powder is extracted from the cartridge 1, with the empty dose enclosures being maintained in the cartridge 1.

[0171] Referring to fig. 3, there is disclosed a silicon dose 10, comprising an amount of silicon powder 15 enclosed in a space 13 by an enclosure 11, 12.

[0172] The enclosure 11, 12 may be formed of a recyclable material, which preferably has good oxygen barrier properties, such as a polymer material and / or a metal material, in particular aluminium. In the illustrated example, the enclosure may be formed with a bottom enclosure part 11 and a top enclosure part 12, which are hermetically sealed, e.g. by an adhesive or by fusing / welding.

[0173] The space 13 enclosed by the enclosure 11, 12 and holding the silicon powder 15 may be oxygen-reduced as compared to surrounding atmosphere. For example, the space 13 may enclose a full or partial vacuum or an inert gas.

[0174] A plurality of doses 10 as disclosed in fig. 3 may be held by the cartridge 1 disclosed in fig. 2. The silicon doses 10 may be opened by a cutting or tearing action, which may be followed or combined with by a separating action, which separates parts of the enclosure 11, 12, such that all of the silicon powder 15 can be released.

[0175] The cartridge 1 may have a standardized external shape that enables it to be stacked for transport and storage. In particular, the cartridge may have ridges, protrusions, or the like on an upper side that may fit with recesses providing in its lower side, or vice versa, such that stacked cartridges 1 will be less prone to shift.

[0176] Referring to fig. 4, there is illustrated a schematic diagram of a silicon powder supply unit 100 according to a second embodiment, wherein the silicon powder supply unit is configured to receive a cartridge 1 holding a plurality of silicon doses 10a, 10b, 10c, lOd, lOe, .., lOn in a cartridge receptacle 101.

[0177] In the embodiment of fig. 4, the silicon doses are configured with a water soluble and hermetically sealed enclosure.

[0178] Consequently, each silicon dose 10 is extracted from the cartridge 1 at the cartridge receptacle 101 and fed in its entirety via the dose feeder 103 to the reactor 120.

[0179] With the dose enclosure 14, 16 being water soluble, the silicon powder 15 will be released in the reactor as the dose enclosure 14, 16 (fig. 5) is dissolved by the water present in the reactor 120.

[0180] Optionally, the silicon dose 10 may be cut, torn or crushed open, so as to speed up the release of the silicon powder 15 into the reactor 120.

[0181] Referring to fig. 5, the space 13 enclosed by the enclosure 14, 16 and holding the silicon powder 15 may be oxygen-reduced as compared to surrounding atmosphere. For example, the space 13 may enclose a full or partial vacuum or an inert gas.

[0182] Referring to fig. 6, there is illustrated a schematic diagram of a silicon powder supply unit 100 according to a third embodiment, wherein the silicon powder supply unit is configured to receive a cartridge 1 holding a plurality of silicon doses 10a, 10b, 10c, lOd, lOe, .., lOn in a cartridge receptacle 101.

[0183] In the embodiment of fig. 6, each silicon dose 10 (fig 17) is provided as a cohesive block 151 of silicon powder particles 152, wherein the block 151 may optionally be encased in an enclosure 17, so as to prevent the block 151 from contact with oxygen. The block may be formed as a briquette or as a pellet.

[0184] Alternatively, the block may be formed of larger silicon particles.

[0185] Silicon doses are extracted from the cartridge 1 at the cartridge receptacle 101 to be fed to a converter 104, which grinds or crushes the silicon blocks 151 so as to form loose the silicon powder 15' that is to be fed to the reactor 120.

[0186] In the case where the silicon dose is formed of a powder of nano-sized particles, there is no need to reduce the size of the actual particles. However, in a case where the silicon dose is formed of larger particles, it may be necessary to grind or otherwise divide such particles into nano-sized particles.

[0187] In the event the silicon block 151 is encased in an enclosure 17, the enclosure may be removed before the conversion. Alternatively, the enclosure may be ground or crushed by the converter 104 and subsequently separated from the silicon powder 15' for recycling or fed to the reactor 120 with the silicon powder 15'.

[0188] Referring to fig. 8, there is illustrated a schematic diagram of a silicon powder supply unit 100 according to a fourth embodiment, wherein the silicon powder supply is connected to a silicon powder production unit 105, which produces silicon powder from a supply of silicon oxide 106 (either recycled silicon oxide or raw silicon oxide, such as quartz) and a supply of electric power 107, and optionally any supporting chemicals conventionally used for such processes.

[0189] The silicon powder production unit 105 may comprise a grinding / crushing device for forming sufficiently small silicon powder particles that are fed to the dose feeder 103 for further feeding in the form of loose silicon powder 15' to the reactor 120.

[0190] The silicon powder production unit 105 may be configured to output silicon in the form of doses, which each contain a predetermined amount of silicon, typically by weight.

[0191] Hence, the silicon powder production unit 105 may be integrated with the system, and in particular with the reactor 120.

[0192] Referring to fig. 9, there is illustrated an example of a cartridge 1 for silicon doses 10a, 10b, 10c, lOd, lOe, lOf.

[0193] The cartridge comprises a housing 2, which may be hermetically sealed and which may be designed with ridges / protrusions / recesses, as mentioned above. The housing 2 may encase a feed mechanism 3a, 3b, 4, which may feed the silicon doses 10a, 10b, 10c, lOd, lOe, lOf such that full silicon doses 10a, 10b, 10c, lOd are fed towards an outlet opening 6 and empty silicon doses lOe, lOf are retained in the cartridge for recycling.

[0194] To this end, the feed mechanism 3a, 3b, 4 may comprise one or more drive pulleys 3a, 3b and a conveyor 4, which may be adapted to hold the silicon doses 10a, 10b, 10c, lOd, lOe, lOf.

[0195] The cartridge 1 may comprise an opener 5, for opening the silicon does so as to release silicon powder.

[0196] The feed mechanism may be provided in a variety of ways, with the present disclosure only providing a non-limiting example.

[0197] The opener may be integrated in the cartridge, or it may form part of the silicon powder supply unit 100, and in particular of the cartridge receptacle 101. For example, the opener 5 may be inserted through a slot in the housing 2 when the cartridge 1 is received in the cartridge receptacle 101.

[0198] A drive mechanism for driving the feed mechanism may be included in the cartridge, e.g. in the form of a biasing arrangement or a motor.

[0199] Alternatively, the drive mechanism may be provided in the silicon powder supply unit 100, and in particular of the cartridge receptacle 101, e.g. in the form of a drive motor which engages the feed mechanism when the cartridge is inserted into the cartridge receptacle 101.

[0200] A counter may be provided in the cartridge 1 or in the cartridge receptacle 101, based on which it can be determined how many silicon doses are left in the cartridge 1.

[0201] In the embodiment where the enclosure of the silicon doses is water soluble, there may be no need for the opener 5. Instead, a release mechanism may be provided for releasing the silicon doses from the feed mechanism to allow them to be extracted from the cartridge 1.

[0202] Referring to fig. 10, there is disclosed a system for producing hydrogen gas, which can be applied to a mobile platform.

[0203] In this context, a mobile platform 1000 may be a vehicle, such as an automobile, a lorry / truck, a bus or a construction machine. A mobile platform may also be a tracked vehicle, such as a train, a tram, or the like. Further, a mobile platform may be a water vessel, such as a surface vessel or a submarine. Yet further, a mobile platform may be an aircraft, which may be manned or unmanned, such as an airplane or a helicopter.

[0204] A consumer 500 in this context may thus be a hydrogen fuel cell or a hydrogen combustion engine.

[0205] A controller 600 may be provided as a central controller, controlling all components of the system. However, one or more components of the system may operate autonomously.

[0206] A silicon powder supply 100 is provided in accordance with any of the various types of silicon power supplies disclosed above.

[0207] Likewise, a water supply 110 is provided in accordance with what has been disclosed above.

[0208] A reactor 120 is provided in accordance with what has been disclosed above.

[0209] A silicon oxide management device 300 may optionally be provided in accordance with what has been disclosed above and connected to the reactor 120 to receive silicon oxide residues from the reactor 120.

[0210] The silicon oxide management device 300 may comprise a dryer (not shown) for drying the silicon oxide. Such dryer may comprise a condenser (not shown), configured for condensing water that has been removed from the silicon oxide during its drying. The condenser may be connected to the water supply 110 or to the reactor 120 so as to return water to the water supply 110 or to the reactor 120, as the case may be.

[0211] The silicon oxide management device 300 may further comprise a silicon oxide container (not shown) for receiving silicon oxide, which may have been dried. The silicon oxide container may be removably connected to the silicon oxide management device 300, such that it can be readily removed when full, and replaced with an empty container.

[0212] The silicon oxide container may be sealed or sealable, such that silicon oxide contained therein is prevented from being dispersed outside the the silicon oxide container.

[0213] A waste water management system 200 may optionally be provided as described above. A hydrogen gas dryer unit 140 may be connected to the reactor 120 to receive hydrogen gas formed in the reactor and to remove water from the hydrogen gas. To this end, the hydrogen gas dryer unit may comprise a condenser and / or a heat exchanger.

[0214] Water removed from the hydrogen gas may be recycled to the water supply 110 or directly to the reactor 120.

[0215] A hydrogen gas compressor unit 160 may be provided and connected to the reactor hydrogen gas dryer unit 140 to receive dried hydrogen gas produced by the reactor 120.

[0216] The hydrogen compressor unit 160 may comprise a compressor, a flow control valve and a pressure gauge, which may be connected in series in said order. An output of the hydrogen compressor unit 160 may be connected to the hydrogen storage tank 170. The compressor, the flow control valve and the pressure gauge may be connected to the controller 600, such that the compressor and flow control unit may be controlled by the controller and such that the pressure gauge may provide data to the controller 600.

[0217] The hydrogen storage tank 170 may be sized in accordance with the relevant application. The hydrogen storage tank 170 may be connected or connectable to a consumer 1200 in the form of a hydrogen fuel cell, configured to produce electricity from a supply of hydrogen from the hydrogen storage tank 170 and, optionally, at least partially from a supply of oxygen from an oxygen storage tank 420, if any.

[0218] Optionally, an oxygen compressor unit 410 may be provided and connected to the reactor 120 to receive oxygen gas produced by the reactor 120.

[0219] The oxygen compressor unit 410 may comprise a compressor, a flow control valve and a pressure gauge, which may be connected in series in said order. An output of the oxygen compressor unit 410 may be connected to the oxygen storage tank 420. The compressor, the flow control valve and the pressure gauge may be connected to the controller 600, such that the compressor and flow control unit may be controlled by the controller and such that the pressure gauge may provide data to the controller 600.

[0220] The oxygen storage tank 420 may be sized in accordance with the relevant application. The oxygen storage tank 420 may be connected or connectable to the consumer 500. A water return line 800 may be provided from the consumer 500 to the water supply 110, such that water that is formed in the fuel cell can be recycled.

[0221] Referring to fig. 11, there is disclosed a system 1100 for producing hydrogen gas, which can be installed as a power plant, as a backup generator or as a portable hydrogen gas generator. The hydrogen gas is to be used by a consumer 1200, comprising a hydrogen fuel cell.

[0222] A silicon powder supply 100 is provided in accordance with any of the various types of silicon power supplies disclosed above.

[0223] Likewise, a water supply 110 is provided in accordance with what has been disclosed above.

[0224] A reactor 120 is provided in accordance with what has been disclosed above.

[0225] A silicon oxide management device 300 is provided in accordance with what has been disclosed above and connected to the reactor to receive silicon oxide residues from the reactor 120.

[0226] A waste water management system 200 may optionally be provided as described above.

[0227] A hydrogen gas dryer unit 140 may be connected to the reactor 120 to receive hydrogen gas formed in the reactor and to remove water from the hydrogen gas. To this end, the hydrogen gas dryer unit may comprise a condenser and / or a heat exchanger.

[0228] Water removed from the hydrogen gas may be recycled to the water supply 110 or directly to the reactor 120.

[0229] A hydrogen gas compressor unit 160 may be provided and connected to the reactor hydrogen gas dryer unit 140 to receive dried hydrogen gas produced by the reactor 120.

[0230] The hydrogen compressor unit 160 may comprise a compressor, a flow control valve and a pressure gauge, which may be connected in series in said order. An output of the hydrogen compressor unit 160 may be connected to the hydrogen storage tank 170. The compressor, the flow control valve and the pressure gauge may be connected to the controller 600, such that the compressor and flow control unit may be controlled by the controller and such that the pressure gauge may provide data to the controller 600. The hydrogen storage tank 170 may be sized in accordance with the relevant application. The hydrogen storage tank 170 may be connected or connectable to a consumer 1200 in the form of a hydrogen fuel cell, configured to produce electricity from a supply of hydrogen from the hydrogen storage tank 170 and, optionally, at least partially from a supply of oxygen from an oxygen storage tank 420, if any.

[0231] Alternatively, the hydrogen storage tank 170 may be connected to the system, and a separate consumer hydrogen tank may be provided, which may be releasably connected to the hydrogen storage tank 170, optionally with a compressor provided therebetween, configured to increase pressure, if desired.

[0232] The compressor unit 160 or the hydrogen storage tank 170 may thus either supply the consumer directly with hydrogen gas.

[0233] Alternatively, the compressor unit 160 or the hydrogen storage tank 170 may supply a consumer hydrogen tank.

[0234] Optionally, an oxygen compressor unit 410 may be provided and connected to the reactor 120 to receive oxygen gas produced by the reactor 120.

[0235] The oxygen compressor unit 410 may comprise a compressor, a flow control valve and a pressure gauge, which may be connected in series in said order. An output of the oxygen compressor unit 410 may be connected to the oxygen storage tank 420. The compressor, the flow control valve and the pressure gauge may be connected to the controller 600, such that the compressor and flow control unit may be controlled by the controller and such that the pressure gauge may provide data to the controller 600.

[0236] The oxygen storage tank 420 may be sized in accordance with the relevant application. The oxygen storage tank 420 may be connected or connectable to the consumer 1200.

[0237] A water return line 800 may be provided from the consumer 1200 to the water supply 110, such that water that is formed in the fuel cell can be recycled.

[0238] Optionally, a consumer condenser 810 may be provided at the consumer 1200, for condensing water vapor formed in the consumer 1200, whereby the consumer water return channel 800 may be connected to the consumer condenser 810, to receive condensed water.

[0239] The consumer return channel 800 may return water to the water supply 110 or directly to the reaction chamber 120. Figs 12a-12d schematically illustrate an extraction and compression sequence, during which a silicon dose 10, in particular a silicon dose having nonwater soluble enclosure 11, 12 is opened, emptied and compressed for recycling.

[0240] The enclosure 11, 12 may optionally provide two spaces 13, 18, wherein a first space 13 contains the silicon powder and the second space 18 contains a helper material, such as a catalyst or a combustion starter. The spaces 13, 18 may, but need not be hermetically separated from each other.

[0241] Fig. 12a schematically illustrates the intact silicon dose 10, in which the first space 13 would be filled with loose silicon powder and in which the second space, if any, would be filled with the helper material.

[0242] Fig. 12b schematically illustrates the opening of the silicon dose 10 by penetration by a lance 50, which may be hollow and have orifices through which compressed gas may be expelled. The lance 50 may be pointed to facilitate penetration of the silicon dose.

[0243] In a first step, as illustrated in fig. 12b, the lance 50 may penetrate through the entire dose enclosure 11, 12. Subsequently, the lance 50 may be slightly retracted, such that the silicon powder may escape through one of the penetrated enclosure walls.

[0244] As illustrated in fig. 12c, the lance 50 may, when slightly retracted, be used to inject compressed gas, such as air, or a liquid, such as water, into the silicon dose 10', in order to drive out any remaining silicon powder, and optionally to release any silicon powder which may be stuck.

[0245] As illustrated in fig. 12d, subsequent to having been emptied, the silicon dose 10' may be compressed into e.g. a generally flat piece of material 10" to facilitate its recycling.

[0246] The sequence illustrated in figs 12a-12d may be particularly applicable to silicon doses having an enclosure 11, 12 of a metallic material, such as aluminium.

[0247] The emptied, and optionally compressed, silicon doses may remain attached to a web, or held by a conveyor 4, as the case may be.

[0248] Fig. 13 discloses a silicon block 3000 comprising a silicon body 3001 formed of a plurality of pressed together silicon particles 3002 having a level of purity corresponding to about 45 % to less than 95 % by weight silicon and a particle size of at least about 1-250 mm, about 5-100 mm, about 10-100 mm, about 20-80 mm or about 10-80 mm.

[0249] The particles 3000 may, but need not, be formed of polycrystalline silicon.

[0250] In various embodiments, the particle size may be about 1-250 mm, about 5-100 mm, about 10-100 mm, about 20-80 mm or about 10-80 mm.

[0251] As non-limiting examples, the silicon block 3000 may have a volume of 1- 2000 dm3, preferably 50-1000 dm3. However, larger blocks 3000 are not excluded.

[0252] In use, a plurality of such silicon blocks 3000 may be arrayed, such as stacked, or otherwise arranged to form a larger thermal accumulator.

[0253] In a silicon block 3000 as described above, energy can be stored at a capacity of more than 1 MWh per cubic metre of silicon at a temperature of 1400 degC. Hence, energy may be stored in the silicon block at 120-1400 degC and in particular at 120-200 degC, 200-300 degC, 300-400 degC, 400-500 degC, 500-600 degC, 600- 700 degC, 700-800 degC, 800-900 degC, 900-1000 degC, 1000-1100 degC, 1100-1200 degC, 1200-1300 degC, 1300-1400 degC or 1400-1414 degC.

[0254] Higher temperatures, up to about 3265 degC, which is the boiling temperature of silicon, can be used. Provided appropriate measures are taken, it may be desirable to allow a plurality of silicon blocks to melt or fuse into a single block, and / or to store energy in silicon when it is in liquid state.

[0255] Optionally, heat conductors may be arranged in spaces between such arrayed silicon blocks 3000.

[0256] Alternatively, or as a supplement, channels can be formed in the silicon block 3000, in which a heated medium may be conveyed.

[0257] The silicon block 3000 may be formed according to a standardized size, such that silicon blocks 3000 can be stacked and handled rationally. To this end, the silicon block may be provided with connectors, for interconnection of two or more silicon blocks 3000. Such interconnectors may, as a non-limiting example, be provided in a manner similar to the basic Lego® blocks, i.e. with one or more downwardly open receptacles and one or more upwardly protruding projections matching said receptacles.

[0258] At higher temperatures, such as above 1350 degC, in particular above 1400 degC, i.e. close to the melting point of silicon, silicon blocks may bond thermally to each other. In some embodiments, the silicon powder may comprise, consist, or consist essentially of, silicon particles, which are provided with a water-soluble coating, configured to delay the particles' reaction with the water.

[0259] As a non-limiting example, a water-soluble polymer that can effectively stabilize silicon nanoparticles is poly-ethylene glycol ("PEG"), which provides a steric hindrance and prevents the nanoparticles from aggregating. The technology as such has been used before in applications such as drug delivery systems and wastewater treatment.

[0260] One of the primary factors that influence the dissolution time of PEG coatings in water is the molecular weight of the PEG. PEGs with lower molecular weights, such as "PEG 200" or "PEG 400", tend to dissolve relatively quickly in water. These lower molecular weight PEGs can dissolve within minutes to a few hours, depending on the thickness of the coating. PEGs with higher molecular weights, such as "PEG 8000" or "PEG 20,000", they may take longer to dissolve in water. The larger size and more complex structure of these higher molecular weight PEGs result in slower dissolution rates (several hours or even longer to dissolve completely in water).

[0261] In short: a thicker PEG shell can offer enhanced stability, while a thinner coating may allow for greater interaction with the water.

[0262] The process of coating a nanoparticle with polyethylene glycol (PEG) typically involves a surface modification technique known as PEGylation. PEGylation refers to the covalent attachment of PEG chains onto the surface of nanoparticles to create a protective coating and can be made in a non-aqueous solution.

[0263] In such a process, silicon nanoparticles would be provided and provided, in a non-aqueous solvent, with a surface activation agent, after which PEG molecules will be attached to the silicon nanoparticles through covalent bonding "PEGylation", also in a non aqueous solution.

[0264] By combining amounts of silicon nanoparticles having differently configured coatings, it is possible to provide a silicon dose, in which silicon is released to react with the water continuously or intermittently, rather than all at once. Hence, a silicon dose may comprise a first amount of silicon particles having a first coating which provides a first release time in water and a second amount of silicon particles having a second coating which provides a second release time in water, whereby the second release time is longer than the first release time. Optionally, such a silicon dose may also contain uncoated silicon particles.

Claims

CLAIMS1. A method of producing hydrogen by reacting silicon powder and water, comprising: providing water in a reactor, providing loose silicon powder in the reactor, dispersing the silicon powder in the water in the reactor, and collecting hydrogen gas from the reactor, characterized in that the silicon powder is provided as a plurality of silicon doses, each silicon dose comprising a predetermined amount of the silicon powder.

2. The method as claimed in claim 1, further comprising: continuously or intermittently determining a hydrogen production rate, identifying when the hydrogen production rate drops below a threshold rate, and when the hydrogen production rate drops below the threshold rate, feeding at least one additional silicon dose to the reactor.

3. The method as claimed in any one of the preceding claims, wherein said determining a hydrogen production rate comprises measuring at least one parameter indicative of the hydrogen production ratio.

4. The method as claimed in any one of the preceding claims, wherein said determining a hydrogen production rate comprises estimating the hydrogen production ratio based on historical data of the hydrogen production rate and / or based on a prediction model of the hydrogen production rate.

5. The method as claimed in any one of the preceding claims, wherein each of the silicon doses is individually encapsulated in an oxygen-reduced space formed by an enclosure.

6. The method as claimed in any one of the preceding claims, wherein at least some of the silicon doses are provided in a non-water soluble enclosure, wherein the method further comprises opening the enclosure encapsulating said predetermined amount of silicon powder, so as to release the silicon powder.

7. The method as claimed in any one of claims 1-5, wherein at least some of the silicon doses are provided in a water soluble enclosure, wherein the method further comprises feeding said silicon dose to the reactor, such that the water soluble enclosure is dissolved, so as to release the silicon powder.

8. The method as claimed in any one of claims 1-5, wherein at least some of the silicon doses are provided as cohesive bodies of the silicon powder, or in the form of silicon pellets or silicon briquettes having larger particle size than the silicon powder, and wherein the method further comprises: converting at least some of the cohesive bodies of the silicon powder into loose silicon powder, or converting at least some of said silicon pellets or silicon briquettes having larger particle size than the silicon powder into loose silicon powder, whereby a particle size is reduced.

9. The method as claimed in any one of the preceding claims, further comprising: receiving a set comprising a plurality of silicon doses, and selectively feeding said at least one of said silicon doses from the set to the hydrogen reactor, to a dose opener or to a dose converter, as the case may be.

10. The method as claimed in claim 9, wherein the set comprises a cartridge comprising a plurality of silicon doses, and wherein the method comprises selectively feeding said at least one of said silicon doses from the cartridge to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

11. The method as claimed in claim 9, wherein the set comprises a web to which the plurality of silicon doses are connected, and wherein the method comprises releasing at least one of said silicon doses from the web and feeding it to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

12. The method as claimed in any one of claims 1-4, further comprising: providing silicon oxide, reducing the silicon oxide into said silicon, optionally converting the silicon into silicon powder, and dividing said silicon powder into said silicon doses.

13. The method as claimed in any one of the preceding claims, wherein the method is performed in a stationary installation.

14. The method as claimed in any one of claims 1-10, wherein the method is performed in a mobile installation.

15. The method as claimed in any one of the preceding claims, further comprising providing a catalyst to the reactor.

16. The method as claimed in any one of the preceding claims, wherein each silicon dose comprises an effective amount of the catalyst.

17. The method as claimed in any one of the preceding claims, wherein the silicon powder comprises silicon particles, which are provided with a water- soluble coating, configured to delay the particles' reaction with the water.

18. A system for producing hydrogen by reacting silicon powder and water, comprising: a reactor for reacting the water and the silicon powder, a silicon supply unit for feeding individual doses of the silicon powder, each dose comprising a predetermined amount of the silicon powder, a water supply unit for feeding water to the reactor, a controller, configured to: determine a hydrogen production rate, identify when the hydrogen production rate drops below a threshold rate, and control the silicon supply unit for feeding at least one additional silicon dose when the hydrogen production rate drops below the threshold rate.

19. The system as claimed in claim 18, further comprising a dose opener, configured to open an enclosure encapsulating said predetermined amount of silicon powder, so as to release the silicon powder.

20. The system as claimed in claim 18, wherein the feed device is configured to feed a silicon dose into the reactor while the silicon dose is enclosed in an encapsulation.

21. The system as claimed in claim 18, further comprising a dose converter, configured to: convert a cohesive body of the silicon powder into loose silicon powder, or convert silicon pellets or silicon briquettes having larger particle size than the silicon powder into loose silicon powder, whereby a particle size is reduced.

22. The system as claimed in any one of claims 18-21, wherein the feed device comprises a dose cartridge handling device, configured to: receive a cartridge comprising a plurality of silicon doses, and selectively feed said at least one of said silicon doses from the cartridge to the hydrogen reactor, to the dose opener or to the dose converter, as the case may be.

23. The system as claimed in claim 18, further comprising: a silicon powder production device, configured for producing silicon powder from silicon oxide, the silicon powder production device being directly connected to the feed device.

24. An energy carrier, comprising: a predetermined amount of silicon powder, the silicon powder having a level of purity of at least 45 % by weight, an enclosure, encapsulating said silicon powder, wherein a space encapsulated by the enclosure is oxygen-reduced.

25. The energy carrier as claimed in claim 24, wherein the silicon powder is essentially non-compressed.

26. The energy carrier as claimed in claim 24, wherein the silicon powder is compressed to form a cohesive body.

27. The energy carrier as claimed in any one of claims 24-26, wherein the silicon powder is vacuum-packaged in the enclosure.

28. The energy carrier as claimed in any one of claims 24-26, wherein the silicon powder is contained in an effectively inert atmosphere in the enclosure.

29. The energy carrier as claimed in any one of claims 24-28, wherein the enclosure is non-water soluble.

30. The energy carrier as claimed in any one of claims 24-28, wherein the enclosure is water soluble.

31. The energy carrier as claimed in any one of claims 24-30, wherein the predetermined amount is about 1-500 g.

32. The energy carrier as claimed in any one of claims 24-31, wherein the silicon powder has a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70- 80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

33. The energy carrier as claimed in any one of claims 24-32, wherein the silicon powder comprises silicon particles, which are provided with a water-soluble coating, configured to delay the particles' reaction with the water.

34. A cartridge, comprising a cartridge housing enclosing a plurality of energy carriers as defined in any one of claims 24-33.

35. The cartridge as claimed in claim 34, wherein the cartridge is configured to retain or receive emptied enclosures.

36. A cartridge, comprising a cartridge housing enclosing a plurality of energy carriers, each of which being provided as a cohesive body of silicon powder having a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

37. The cartridge as claimed in any one of claims 34-36, wherein the cartridge comprises a feed mechanism for causing the energy carriers to move towards an opening in the housing.

38. The cartridge as claimed in any one of claims 34-37, wherein the cartridge housing presents engagement members for engagement with identical cartridge housings to counteract said cartridge housings shifting when arranged as a stack.

39. An energy carrier assembly, comprising a plurality of energy carriers as defined in any one of claims 24-33 and a web, wherein the energy carriers are supported by the web.

40. A method of feeding an energy carrier as claimed in any one of claims 24-33, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising opening the enclosure prior to feeding the silicon powder into the water.

41. A method of feeding an energy carrier as claimed in any one of claims 24-33, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising depositing the energy carrier into the water and allowing the enclosure to dissolve so as to release the silicon powder.

42. A method of feeding an energy carrier in the form of silicon powder, into a reactor for producing hydrogen by reacting silicon powder and water, the method comprising: providing a body of silicon, converting said silicon into silicon powder, and feeding said silicon powder into the reactor.

43. The method as claimed in claim 42, further comprising removing or opening an encapsulation from the cohesive body prior to said converting.

44. The method as claimed in claim 42, further comprising converting an encapsulation encapsulating the cohesive body during said converting.

45. The method as claimed in any one of claims 42-44, wherein the silicon powder is provided as, or converted into, silicon powder having a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80-90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

46. An energy carrier, comprising a cohesive silicon powder body which is formed of a silicon powder, said silicon powder having a level of purity corresponding to about 45 % to less than 95 % by weight silicon and a particle size which is less than about 0.5 mm.

47. The energy carrier as claimed in claim 46, wherein the silicon has a particle size of about 1-100 pm, about 100-200 pm, about 200-300 pm, about 300- 400 pm or about 400-500 pm.

48. The energy carrier as claimed in claim 47, wherein the silicon powder has a particle size of about 1-10 nm, about 10-20 nm, about 20-30 nm, about 30-40 nm, about 40-50 nm, about 50-60 nm, about 60-70 nm, about 70-80 nm, about 80- 90 nm, about 90-100 nm, about 100-200 nm, about 200-300 nm, about 300-400 nm, about 400-500 nm, about 500-600 nm, about 600-700 nm, about 700-800 nm, about 800-900 nm or about 900-1000 nm.

49. Use of an energy carrier as claimed in any one of claims 46-48 in a hydrogen production process, comprising: converting the silicon powder body into loose powder, and causing said loose powder to react with water to form hydrogen and silicon oxide.

50. Use of an energy carrier as claimed in any one of claims 46-48 in an energy conversion process, comprising: converting the silicon powder body into loose powder, and causing said loose powder to undergo a combustion process in the presence of oxygen.

51. An energy carrier, comprising a cohesive body which is formed of silicon particles having a level of purity corresponding to about 45 % to less than 95 % by weight silicon and a particle size of at least about 1-250 mm, about 5-100 mm, about 10-100 mm, about 20-80 mm or about 10-80 mm.

52. The energy carrier as claimed in claim 51, wherein the body has a mass of at least about 50 kg, preferably about 50-3000 kg.

53. The energy carrier as claimed in claim 51 or 52, wherein the body has a density near room temperature of less than about 2329 kg / m3.

54. Use of an energy carrier as claimed in any one of claims 51-53, for accumulating thermal energy, said thermal energy having a temperature greater than 120 degC, preferably greater than 200 degC, greater than 300 degC, greater than 400 degC or greater than 500 degC, and less than about 3265 degC, preferably less than about 2500 degC or less than 1414 degC.

55. A system for producing hydrogen, comprising: a reactor for reacting water and silicon powder to produce hydrogen gas, a silicon supply unit connected to the reactor for supplying loose silicon powder to the reactor, a water supply unit connected to the reactor for supplying water to the reactor, a hydrogen dryer unit connected to the reactor for receiving hydrogen gas from the reactor and for supplying dried hydrogen gas, a controller for controlling at least some of the silicon supply unit, the water supply unit, the reactor, the hydrogen dryer, and the hydrogen compressing unit.

56. The system as claimed in claim 55, further comprising a hydrogen compressing unit connected to the hydrogen dryer for receiving dried hydrogen gas.

57. The system as claimed in claim 55 or 56, further comprising a hydrogen storage tank connected to the hydrogen compressing unit for receiving compressed hydrogen gas from the hydrogen compressing unit.

58. The system as claimed in any one of claims 55-57, further comprising a consumer, connectable to the hydrogen compressing unit or to the hydrogen storage tank, for receiving hydrogen gas and for converting the hydrogen gas into thermal, mechanic and / or electric energy.

59. The system as claimed in any one of claims 55-58, further comprising an oxygen compressing unit connected to the reactor for receiving oxygen gas from the reactor and for supplying compressed oxygen gas to an oxygen gas storage tank.

60. The system as claimed in claim 59, wherein the oxygen gas storage tank is connected to the consumer for supplying oxygen gas to the consumer.

61. The system as claimed in any one of claims 55-60, wherein the consumer comprises a hydrogen fuel cell.

62. The system as claimed in any one of claims 55-61, wherein the consumer comprises a hydrogen combustion engine.

63. The system as claimed in any one of claims 55-62, further comprising a consumer water return channel for returning water from the consumer to the water supply unit or to the reactor.

64. The system as claimed in any one of claims 55-63, further comprising a hydrogen dryer water return channel for returning water from the hydrogen dryer to the water supply unit or to the reactor.

65. The system as claimed in any one of claims 55-54, further comprising a silicon oxide management system comprising a silicon oxide dryer and a silicon oxide water return channel for returning water from the silicon oxide management system to the water supply unit or to the reactor.

66. The system as claimed in any one of claims 55-65, wherein the a silicon supply unit is configured for feeding individual doses of the silicon powder, each dose comprising a predetermined amount of the silicon powder, andwherein the controller is configured to: determine a hydrogen production rate, identify when the hydrogen production rate drops below a threshold rate, and control the silicon supply unit for feeding at least one additional silicon dose when the hydrogen production rate drops below the threshold rate.

67. The system as claimed in any one of claims 55-66, wherein at least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller are supported by a mobile platform, in particular a vehicle, vessel or aircraft.

68. The system as claimed in any one of claims 55-66, wherein at least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller are provided as a fixed construction.

69. The system as claimed in any one of claims 55-66, wherein at least said reactor, silicon supply unit, water supply unit, hydrogen dryer unit, hydrogen compressing unit and controller are provided as a portable unit.

70. A system for converting energy, comprising: a reactor for reacting water and silicon powder to produce hydrogen gas, a silicon supply unit connected to the reactor for supplying loose silicon powder to the reactor, a water supply unit connected to the reactor for supplying water to the reactor, a consumer, connectable to the hydrogen compressing unit or to the hydrogen storage tank, for receiving hydrogen gas and for converting the hydrogen gas into thermal, mechanic and / or electric energy, anda consumer water return channel for returning water from the consumer to the water supply unit or to the reactor.

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