System and method for biofuel storage

Abstract

System (1) for biofuel storage and having: a tank (2) configured to contain the biofuel; a thermal conditioning unit (3) configured to maintain the biofuel that is inside the tank (2) at a desired temperature; a delivery unit (6) configured to draw biofuel that is inside the tank (2) to supply the biofuel to a tank of an external user device; an atmosphere conditioning unit (4) configured to maintain inside the tank (2) a controlled atmosphere; and an additivation unit (5) configured to add at least one additive to the biofuel that is inside the tank (2).

Description

[0001] SYSTEM AND METHOD FOR BiOFUEL STORAGE

[0002] Cross-Reference to Related Patent Applications

[0003] This application claims the priority of Italian Patent Application No. 102024000026031 filed on November 19, 2024, the content of which is hereby incorporated by reference.

[0004] Technical Field

[0005] The present invention relates to a system and a method for biofuel storage.

[0006] The present invention finds advantageous application to biodiesel storage, to which the discussion will make explicit reference without thereby losing generality.

[0007] Prior Art

[0008] Biodiesel is perishable over time due to its hygroscopic nature and low oxidation stability. The absorption of moisture from the atmosphere triggers chemical reactions that degrade the esters, while oxidative instability leads to the formation of peroxides, acids, aldehydes, and polymers.

[0009] The management of biodiesel in cold climates is particularly problematic, as it solidifies at low temperatures (higher than diesel from petroleum).

[0010] The phase transition of biodiesel from liquid to solid does not occur at a specific temperature, but in a range characterized by critical points: the Cloud Point (between -5°C and 15°C), the Pour Point (3-5°C lower than the Cloud Point), and the Cold Filter Plugging Point (CFPP), intermediate between the two. These temperatures vary based on the source material of origin.

[0011] Consequently, these intrinsic characteristics entail risks of biodiesel degradation, damage to storage and distribution systems, and operational problems in engines, especially in adverse climatic conditions.

[0012] Patent application W02009092001 A2 describes a refueling station for clean or low-emission fuels; the refueling station comprising at least one fuel tank, a fuel modification network in fluid communication with the tank, and at least one delivery nozzle connected with the modification network to receive the treated fuel (for example heated) from the modification network.

[0013] Description of the Invention

[0014] The purpose of the present invention is to provide a system and a method for biofuel storage that allow for the conservation of biofuel even for a long period of time without the biofuel being subject to degradation and that allow for always having biofuel liquid ready for use, even in cold climates.

[0015] According to the present invention, a system and a method for biofuel storage are provided, according to what is claimed by the attached claims.

[0016] The claims describe preferred embodiments of the present invention forming an integral part of the present description.

[0017] Brief Description of the Drawings

[0018] The present invention will now be described with reference to the attached drawings, which illustrate a non-limiting example of implementation thereof, in which:

[0019] • Figure 1 is a schematic view of a biodiesel storage system;

[0020] • Figure 2 is a schematic view of a thermal conditioning unit of the storage system of Figure 1 ;

[0021] • Figures 3, 4 and 5 show the thermal conditioning unit of Figure 2 with emphasis on the paths followed by fluids during different operating modes;

[0022] • Figure 6 is a schematic view of an atmosphere conditioning unit of the storage system of Figure 1 ;

[0023] • Figures 7, 8 and 9 show the atmosphere conditioning unit of Figure 6 with emphasis on the paths followed by fluids during different operating modes;

[0024] • Figure 10 is a schematic view of an additivation unit of the storage system of Figure 1 ;

[0025] • Figures 11 and 12 show the additivation unit of Figure 10 with emphasis on the paths followed by fluids during different operating modes;

[0026] • Figure 13 is a schematic view of a delivery unit of the storage system of Figure 1 ;

[0027] • Figure 14 shows the delivery unit of Figure 13 with emphasis on the paths followed by fluids during operation.

[0028] Preferred Embodiments of the Invention

[0029] In Figure 1 , with reference number 1 a biofuel storage system is indicated as a whole, in particular biodiesel.

[0030] The storage system 1 comprises a tank 2 that is configured to contain the biodiesel and represents the heart of the storage system 1. The tank 2 may or may not be thermally insulated in order to increase the thermal inertia of the biodiesel contained in it. The insulation can be obtained, by way of example, through layers of insulating material such as rock or glass wool, appropriately waterproofed, or through a second steel wall containing air or under vacuum.

[0031] The storage system 1 comprises a thermal conditioning unit 3 configured to maintain the biodiesel that is inside the tank 2 at a desired temperature, that is to heat (or, more rarely cool) the biodiesel that is inside the tank 2.

[0032] The storage system 1 comprises an atmosphere conditioning unit 4 configured to maintain inside the tank 2 (that is in the upper part of the tank 2 not occupied by the biodiesel) a controlled atmosphere.

[0033] The storage system 1 comprises an additivation unit 5 configured to add one or more additives to the biodiesel that is inside the tank 2.

[0034] The storage system 1 comprises a delivery unit 6 configured to draw biodiesel that is inside the tank 2 to supply the biodiesel to the tank of a vehicle (terrestrial, naval or aerial) or to the tank of an utilizer machinery (which can be any equipment also different from a vehicle and equipped with an internal combustion engine).

[0035] In the embodiment illustrated in the attached figures, the storage system 1 comprises all three units 3, 4 and 5; according to other embodiments not illustrated, the storage system 1 comprises only two of the three units 3, 4 and 5 or only one of the three units 3, 4 and 5.

[0036] According to what is illustrated in Figure 2, the thermal conditioning unit 3 comprises a conditioning hydraulic circuit 7 in which a thermal fluid flows (typically water-based to which antifreeze and antivegetative additives are generally added) that can be heated (or more rarely cooled) to heat (or more rarely cool) the biodiesel that is inside the tank 2.

[0037] The conditioning hydraulic circuit 7 comprises a heat exchanger 8 that is coupled to the tank 2 (typically it is arranged inside the tank 2 in direct contact with the biodiesel) and performs a thermal exchange between the thermal fluid that is circulated inside the heat exchanger 8 and the biodiesel that is in the tank 2. By way of example, the heat exchanger 8 could comprise a cylindrical-shaped coil arranged inside the tank 2, or it could comprise a tube inside which the thermal fluid flows and which is wound in a spiral.

[0038] The conditioning hydraulic circuit 7 comprises a heat exchanger 9 that is arranged outside the tank 2 and performs a thermal exchange between the thermal fluid that is circulated inside the heat exchanger 9 and the biodiesel that is circulated outside the tank 2; for this purpose, the thermal conditioning unit 3 comprises a circulation hydraulic circuit 10 configured to circulate a part of the biodiesel that is inside the tank 2 through the heat exchanger 9. In particular, the circulation hydraulic circuit 10 comprises its own pump 11 that can be activated to circulate the biodiesel along the circulation hydraulic circuit 10 and therefore through the heat exchanger 9. The circulation hydraulic circuit 10 can be used to move the biofuel that is inside the tank 2 as the simple movement itself reduces biological activity. In the circulation hydraulic circuit 10 there can also be filters, with the function of retaining the impurities formed and, if of the water separation type, with the function of retaining the water adsorbed by the biodiesel. In this regard, it is important to note that a circulation hydraulic circuit 10 independent of the heat exchanger 9 and having only the function of moving the biofuel that is inside the tank 2 could also be provided; that is, this circulation hydraulic circuit 10 is configured to draw a part of the biofuel that is inside the tank 2 from at least one extraction point, circulate the biofuel outside the tank 2, and then re-introduce the biofuel into the tank 2 in at least one return point different and separate from the extraction point.

[0039] According to other embodiments not illustrated, the conditioning hydraulic circuit 7 comprises only the heat exchanger 8 that is coupled to the tank 2 (that is, the heat exchanger 9 is absent) or only the heat exchanger 9 that is arranged outside the tank 2 (that is, the heat exchanger 8 is absent).

[0040] The conditioning hydraulic circuit 7 comprises a heating device 12 configured to heat the thermal fluid that flows along the conditioning hydraulic circuit 7 and a conditioning device 13 configured to heat (or possibly cool) the thermal fluid that flows along the conditioning hydraulic circuit 7 (according to a different embodiment not illustrated the conditioning device 13 could be absent). The heating device 12 can comprise a burner that can be supplied with a (small) part of the biodiesel that is inside the tank 2; alternatively, the burner can be supplied with another fuel (liquid or gaseous) coming from another dedicated storage system. Alternatively to the burner, when electrical power is available, the heating device 12 can comprise one or more electrical resistances. Instead, the conditioning device 13 (when present) comprises a reversible refrigeration circuit with a heat pump that is supplied with electrical energy; therefore, the conditioning device 13 is capable of heating or cooling. Preferably, the heating device 12 and the conditioning device 13 are connected to each other in parallel so they can be used together or alternatively.

[0041] The conditioning hydraulic circuit 7 comprises a pump 14 configured to circulate the thermal fluid that flows along the conditioning hydraulic circuit 7 through the heat exchanger 8 and a pump 15 configured to circulate the thermal fluid that flows along the conditioning hydraulic circuit 7 through the heat exchanger 9.

[0042] In other words, the conditioning hydraulic circuit 7 comprises the pump 14 configured to circulate the thermal fluid through the heat exchanger 8 and comprises the pump 15 which is separate and independent from the pump 14 and is configured to circulate the thermal fluid through the heat exchanger 9, so that by activating the pump 14 the thermal fluid circulates through the heat exchanger 8 and by activating the pump 15 the thermal fluid circulates through the heat exchanger 9 (and therefore by activating both pumps 14 and 15 the thermal fluid circulates through both heat exchangers 8 and 9).

[0043] In Figure 3 a "slow" mode of temperature conditioning is illustrated which is preferable when the temperature of the biodiesel that is inside the tank 2 is not far from the desired value and one only wants to maintain or at most heat (or cool) a little the biodiesel that is inside the tank 2 (alternatively or in addition to the heating device 12 the conditioning device 13 could be used). The "slow" mode is preferable for maintaining the desired temperature once reached.

[0044] In Figure 4 a "medium" mode of temperature conditioning is illustrated which is preferable when the biodiesel that is inside the tank 2 must be brought quickly to a determined temperature. The aspiration and subsequent re-introduction (that is, the circulation) of the biodiesel from the tank 2 also allows to increase convective motions and homogenize the temperature of the biodiesel inside the tank 2 more rapidly compared to the mode illustrated in Figure 3 (alternatively or in addition to the heating device 12 the conditioning device 13 could be used).

[0045] In Figure 5 a "fast" mode of temperature conditioning is illustrated which is preferable when the biodiesel that is inside the tank 2 is close to critical temperature conditions for which a combined action of the heat exchangers 8 and 9 allows rapid and high heat exchange (alternatively or in addition to the heating device 12 the conditioning device 13 could be used).

[0046] In Figures 3, 4 and 5 the use of only the heating device 12 is shown by way of example; alternatively only the conditioning device 13 could be used or both the heating device 12 and the conditioning device 13 could be used simultaneously.

[0047] According to what is illustrated in Figure 6, the atmosphere conditioning unit 4 comprises a dehumidifier device 16 configured to generate dry air (that is a dry air generator device). By way of example, the dehumidifier device 16 comprises a compressor followed by an air dryer (usually with a refrigeration cycle that condenses atmospheric moisture); alternatively, in its simplest form, the dehumidifier device 16 could be a filter through which air passes thanks to the depression that is created when fuel is drawn from the tank 2 (these filters usually contain salts like "calcium chloride" or materials like "silica gel" that are capable of adsorbing atmospheric water and must be replaced when saturated with water).

[0048] According to a possible embodiment, the tank 2 has a vent (equipped with a one-way valve that allows only the exit of air from the upper part of the tank 2 not occupied by biodiesel) to let out the humid air present as new dry air coming from the dehumidifier device 16 is gradually introduced. According to a possible embodiment, part of the air drawn by the compressor and dried by the dehumidifier device 16 can be drawn directly from the tank 2 and then re-introduced into the tank 2 once treated (dehumidified). The atmosphere conditioning unit 4 comprises a nitrogen generator 17 (that is an inert gas) that is capable of separating nitrogen from dry air and operates (works) together with the dehumidifier device 16 (that is receives dry air from the dehumidifier device 16). Alternatively and in its simplest form, the nitrogen generator 17 could comprise a simple tank containing nitrogen.

[0049] The atmosphere conditioning unit 4 comprises a tank 18 containing carbon dioxide or argon (that is another inert gas different from nitrogen). The function of dry air or an inert gas inside the tank 2 is to slow down the degradation processes of biodiesel that are accelerated by water and oxygen. In the embodiment illustrated in the attached figures, the atmosphere conditioning unit 4 comprises all three the dehumidifier device 16, the generator device 17 and the tank 18; according to other embodiments not illustrated, the atmosphere conditioning unit 4 comprises only two of the dehumidifier device 16, the generator device 17 and the tank 18 or only one of the dehumidifier device 16, the generator device 17 and the tank 18.

[0050] In other words, the atmosphere conditioning unit 4 is configured to introduce dry air, nitrogen and / or another inert gas in an upper part of the tank 2 not occupied by biodiesel.

[0051] Among otherthings, the atmosphere conditioning unit 4 can be configured to increase an internal pressure of the tank 2 so as to confer on the tank 2 an internal pressure higher than atmospheric pressure; the increase of pressure inside the tank 2 allows to reduce, with all other things being equal, the solidification temperature of biodiesel. Furthermore, a positive pressure (that is higher than atmospheric pressure) inside the tank 2 helps the pumps in their operation, especially when temperatures are low and the biodiesel is very viscous.

[0052] In Figure 7 the supply of dry air inside the tank 2 (that is in the upper part of the tank 2 not occupied by biodiesel) is illustrated, in Figure 8 the supply of nitrogen (or other inert gas) coming from the generator device 17 inside the tank 2 (that is in the upper part of the tank 2 not occupied by biodiesel) is illustrated, and in Figure 9 the supply of inert gas coming from the tank 18 inside the tank 2 (that is in the upper part of the tank 2 not occupied by biodiesel) is illustrated.

[0053] The choice of the gas to be introduced into the tank 2 is executed, in addition to on the basis of economic criteria, according to the type of biofuel that one wants to conserve inside the tank 2. By way of example, if in the tank 2 there is a biofuel capable of absorbing carbon dioxide it is preferable to introduce into the tank 2 other inert gases different from carbon dioxide. By way of example, if in the tank 2 there is a hygroscopic biofuel it is sufficient to introduce into the tank 2 dry air, so that there is no trace of water particles in the air. By way of example, if in the tank 2 there is a biofuel susceptible to oxidation it is preferable to introduce into the tank 2 nitrogen or another inert gas.

[0054] According to what is illustrated in Figure 10, the additivation unit 5 comprises a tank 19 containing an additive and a pump 20 that can be activated to draw the additive from the tank 19 and supply the additive into the tank 2. The addition of the additive serves to improve the durability of biodiesel and, in particular, the additive can be used for greater stabilization (that is to prevent degradation caused by heat, light or chemical exposure, ensuring greater duration, stability and lower oxidation), the additive can be used for an antifreeze action (that is to lower the solidification point of biodiesel), or the additive can be used for an antimicrobial action (that is to prevent the growth of microbes and algae). The additive can also be fossil fuel (diesel in case the tank 2 contains biodiesel); in case fossil fuel is used for additivation, the additivation unit 5 can be controlled to create in the tank 2 a desired mixture of diesel and biodiesel. That is, the control unit 23 is configured to maintain inside the tank 2 a mixture of the biofuel (biodiesel) and the fossil fuel (diesel) having a predetermined composition.

[0055] In Figure 11 the use of the additivation unit 5 to supply an additive from the tank 19 to the tank 2 containing biodiesel is illustrated. Instead, in Figure 12 the use of the additivation unit 5 to generate a remixing of the biodiesel that is inside the tank 2 is illustrated. In this hydraulic circuit there can also be filters, with the function of retaining the impurities formed and, if of the water separation type, with the function of retaining the water adsorbed by the biodiesel.

[0056] According to what is illustrated in Figure 13, the delivery unit 6 comprises a pump 20 and a dispenser 21 ; a return line 22 is also provided through which the excess biodiesel (that is not exiting from the dispenser 21) pumped by the pump 20 can return to the tank 2. The hydraulic circuit of the delivery unit 6, when the dispenser 21 is not in operation, can be used to move the biofuel that is inside the tank 2 as the movement reduces biological activity. In the hydraulic circuit of the delivery unit 6 there can also be filters, with the function of retaining the impurities formed and, if of the water separation type, with the function of retaining the water adsorbed by the biodiesel.

[0057] According to a different embodiment, the additivation unit 5, instead of being configured to supply the additive into the tank 2, is configured to supply the additive into the dispenser 21 , that is the additive joins the biodiesel only when the biodiesel is dispensed.

[0058] In Figure 14 the operation of the delivery unit 6 is illustrated.

[0059] According to what is illustrated in Figure 1 , the storage system 1 comprises a control unit 23 that oversees the operation of the storage system 1 .

[0060] The control unit 23 can be configured to control in feedback the temperature of the biodiesel that is inside the tank 2 by accordingly operating the thermal conditioning unit 3; that is the control unit 23 reads at least a measurement of the temperature of the biodiesel that is inside the tank 2 (by means of at least one appropriate temperature sensor or equivalent systems) and compares the temperature of the biodiesel with defined temperature thresholds, stored in a memory unit or generated in real time by appropriate calculation algorithms integrated in the control unit 23. Alternatively, if the storage system 1 is equipped with a biodiesel property sensor (such as, for example, a viscosity sensor), the control unit 23 can be configured to directly control in feedback the viscosity of the biodiesel. The ultimate purpose of heating is in fact to maintain the viscosity (which is a function of temperature) below a threshold value that ensures that the biodiesel is always movable and / or usable in the vehicle or machinery that will be supplied by the storage system 1 .

[0061] The conditioning of the temperature of the biodiesel that is inside the tank 2, in the circulation hydraulic circuit 10 and in the delivery unit 6 can use energy efficiency optimization strategies.

[0062] For example, if the thermal conditioning unit 3 uses mainly electrical energy, the control unit 23 could deactivate the thermal conditioning unit 3 at the end of the evening shift and could reactivate the thermal conditioning unit 3 in the early morning hours (that is when it is still night) so that a slow and controlled heating can be performed by operating the thermal conditioning unit 3 at the point of maximum efficiency. Furthermore, by heating or cooling during the night the biodiesel that is inside the tank 2 more than it is necessary for its maintenance and / or use, it will be possible to delay the activation of the thermal conditioning unit 3 during the daytime hours; in this way, the operation of the thermal conditioning unit 3 is optimized which will be used during daytime hours only to maintain the biodiesel in temperature, thus reducing energy expenditure.

[0063] Instead, if the thermal conditioning unit 3 uses mainly fuel (for example the biodiesel that is inside the tank 2), the control unit 23 will make the thermal conditioning unit 3 more effective by making it work at constant power within its range of maximum efficiency; this allows to minimize the fuel consumption that is higher with an intermittent operation of the thermal conditioning unit 3. The control unit 23 could be able to apply management strategies that combine the operation of the thermal conditioning unit 3 and the additivation unit 5. For example, if during the night temperatures should lower significantly, there could be a risk of biodiesel solidification and therefore the control unit 23 could consider it more effective to add a certain amount of additive to prevent the biodiesel from starting to solidify and activate the thermal conditioning unit 3 only at a later time when the biodiesel needs to have a specific temperature. In some cases it is also possible that a combined action of the two units 3 and 5 is needed, for example, when the addition of additive alone is not sufficient to guarantee the thermal safety of the perishable biodiesel. In these cases the control unit 23 activates the thermal conditioning unit 3 to maintain a temperature value within the limits and introduces a certain amount of additive to protect the biodiesel while waiting for the thermal conditioning unit 3 to come into action. In this way, the thermal conditioning unit 3 performs a slight temperature increase or maintenance action instead of a massive heating or cooling operation that would involve high energy consumption without giving significant results due to the climatic harshness present outside the tank 2.

[0064] The control unit 23 can be able to also use the atmosphere conditioning unit 4 for thermal management of biodiesel. In fact, if one wants to avoid activating the thermal conditioning unit 3 it is possible to increase through the atmosphere conditioning unit 4 the pressure inside the tank 2; this will allow to lower the temperature value after which biodiesel freezes and could replace or integrate the operation of the additivation unit 5.

[0065] The control unit 23 can be configured to monitorthe chemical-physical characteristics of the biodiesel (for example through a fuel property sensor) and prevent it from deteriorating over time by forming algae or microbes or avoiding any reactions with the air present inside the tank 2.

[0066] The operation of preventing the deterioration of biodiesel occurs thanks to the knowledge of the control unit 23 of the characteristics of the biodiesel that is conserving. In fact, it is possible to save in a memory of the control unit 23 a sheet containing the chemical-physical parameters that a certain biodiesel possesses.

[0067] Based on the modification or alteration that the biodiesel is undergoing, the control unit 23 can decide what action to take. Also in this case, the action taken by the control unit 23 is performed to maximize efficiency, therefore the control unit 23 will activate among the various units 3, 4 and 5 present, the one that will have a lower energy impact.

[0068] For example, if the modification of the parameters is essentially due to a variation of the biodiesel temperature, the control unit 23 can decide to activate the thermal conditioning unit 3 or the additivation unit 5 choosing the one that will allow a more rapid regulation and a lower cost in terms of energy.

[0069] If instead the alteration of the biodiesel is due to the partial formation of bacterial organisms or algae, the control unit 23 can activate a remixing of the biodiesel in the tank 2, drawing the biodiesel present in the tank 2 and making it pass through a series of filters that can thus clean the biodiesel, then re-introducing it into the tank 2. Also in this case it is possible, alternatively or in addition to filtering, to introduce into the tank 2 an additive that is capable of performing an antimicrobial action.

[0070] If instead the chemical alteration of the biodiesel is due to an interaction with the atmospheric air present inside the tank 2 it is necessary to replace the latter with a gas or with a mixture of gases based on the characteristics of biodiesel. If for example the biofuel that is being preserved is a hygroscopic biodiesel, the control unit 23 (having in memory the characteristics of the perishable biodiesel or reading them by means of one or more property sensors) knows that it is necessary to eliminate any trace of moisture from the tank 2 (to prevent the moisture from being adsorbed) which is why the control unit 23 will replace the air present inside the tank 2 with dry air (or nitrogen or another inert gas) provided by the atmosphere conditioning unit 4 whenever it detects a trace of moisture in the atmosphere of the tank 2, for example through a humidity sensor.

[0071] The atmosphere conditioning unit 4 can be, in its simplest form, controlled by the control unit 23 as a function of time, that is the atmosphere conditioning unit 4 is activated every set time interval. However, the atmosphere in the tank 2 is to be treated especially when the delivery unit extracts biodiesel from the tank 2, as it is in this circumstance that atmospheric air enters the tank 2; consequently, the atmosphere conditioning unit 4 can be activated simply when the delivery unit 6 is active. According to an alternative embodiment, the control unit 23 has information (read from appropriate sensors) that allows to evaluate the quality of the biodiesel that is inside the tank 2 and therefore allow to establish targeted interventions; such information can be, for example, the humidity of the air in the atmosphere of the tank 2 and the mixture of biodiesel and additive present in the tank 2.

[0072] Since it is impossible to have an indication on all possible biofuel-additive mixtures, in the deteriorated state or not and with all types of biofuel (whether different biofuels such as biodiesel and renewable diesel (HVO) or the same biofuel but from different origins such as biodiesel from palm oil or animal fat), the control unit 23 can be equipped with self-learning algorithms in which every new mixture that is found in the tank 2 is analyzed in its properties and these properties saved on a database. In this way upon the next insertion of a biofuel and the formation of that mixture, the control unit 23 has evaluation parameters that can be used to evaluate the state of deterioration of the biofuel (through the variation of the parameters the deterioration is evaluated).

[0073] The control unit 23 can be connected to company IT systems to integrate with them and consequently make information available to them such as energy consumption (past and forecast), history of quantities dispensed, information on biofuel mixtures (if equipped with a sensor for characterization of the fuel present in the tank 2 or other mixture monitoring systems present such as manual or automatic inputs and / or monitoring of the levels of the tank 2 and the tank 19) used and frequency of supply to the tank 2. If in one company there are multiple storage systems 1 , the control units 23 can be interconnected with each other to exchange information in order to increase company energy efficiency while respecting the fuel demand of the company itself. For example, strategies for balancing the drawings of biofuel from the various storage systems 1 can be implemented to guarantee the fuel demand to the company vehicles or machinery while keeping controlled the levels of the various storage systems 1 , thus keeping the systems at their maximum efficiency. If, for example, all the necessary biofuel were drawn from a single storage system 1 , the atmosphere conditioning unit 4 of the latter would be found to work heavily, increasing its own energy consumption and also the thermal conditioning unit 3 would be found to work at reduced efficiency.

[0074] The control unit 23 can also be directly connected to the vehicle or machinery, so as to exchange information useful for a better management of refueling. For example, a ship that needs to refuel with biodiesel in a certain port, knowing it will reach it in a certain time, can communicate information such as arrival date and quantity required. In this way the control unit 23 of the storage system 1 can start in the most efficient way the biodiesel preparation procedure if sufficient, or if insufficient, communicate to the company systems the need to increase the quantity of biodiesel stored to guarantee the supply to the ship.

[0075] The control unit 23 can also be connected to the internet (loT) thus being able to access forecast maps of atmospheric conditions such as temperature and humidity. Being able to access such information, the control unit 23 is able, through appropriate algorithms, to manage the various units 3, 4 and 5 present in order to minimize energy consumption. For example, if it is forecast that temperatures will drop sharply, the heating unit 3 is controlled in order to supply the required thermal power gradually and efficiently avoiding work peaks.

[0076] When the ambient temperature is low (that is lower than the solidification temperature of biodiesel), in the components in which biodiesel remains stationary for a long time there is a risk of biodiesel solidification; for example, a component at risk of biodiesel solidification in case of prolonged inactivity is the delivery unit 6 when not used for biodiesel movement). To prevent biodiesel solidification in the components in which biodiesel remains stationary it is possible to insert the components in a thermally insulated container (for example an openable sheet metal cabinet lined internally with insulating material); in this way, the heat dispersed by the components of the heating unit 3 contributes to keeping the biodiesel liquid in the ducts and components such as filters. Alternatively or in addition, to prevent biodiesel solidification in the components in which biodiesel remains stationary it is possible to periodically activate (based on time) or based on temperature (read by temperature sensors arranged in the ducts and near critical components) the movement and filtering circuits of the units 3, 5 and 6; in practice the movement allows to heat the critical ducts by circulating in them biodiesel drawn from the tank 2 and therefore hot. In extremely cold climates the two solutions proposed above, even adopted together, can be insufficient to guarantee that biodiesel does not solidify in the ducts; in this case heated ducts and filters can be installed. The ducts and filters can be heated electrically or with the same heating liquid that circulates in the heating unit 3. The description has made explicit reference to the use of biodiesel, but the storage system 1 described above can also be used for the use of a biofuel different from biodiesel.

[0077] The embodiments described here can be combined with each other. For example, the operations allowed by the hydraulic circuits described above can be obtained by varying the arrangement, type and number of components. Furthermore, the optimization strategies forthe use of the units 3, 4, 5 and 6 set out above are only examples, the sensors present and the use that the control unit 23 makes of the information read from them can vary.

[0078] The storage system 1 described above has numerous advantages.

[0079] First, the storage system 1 described above allows for the conservation of biofuel even for a very long period of time without the biofuel being subject to degradation, ensuring that the biofuel remains of good quality and within the manufacturer's specifications, thus preserving the engines that will use it.

[0080] Furthermore, the storage system 1 described above has high energy efficiency as at any time it can choose the action that allows maximum results with minimum energy consumption.

[0081] Finally, the storage system 1 described above is of relatively simple and economical implementation. LIST OF REFERENCE NUMBERS OF THE FIGURES

[0082] 1 storage system

[0083] 2 tank

[0084] 3 thermal conditioning unit

[0085] 4 atmosphere conditioning unit

[0086] 5 additivation unit

[0087] 6 delivery unit

[0088] 7 conditioning hydraulic circuit

[0089] 8 heat exchanger

[0090] 9 heat exchanger

[0091] 10 circulation hydraulic circuit

[0092] 11 pump

[0093] 12 heating device

[0094] 13 conditioning device

[0095] 14 pump

[0096] 15 pump

[0097] 16 dehumidifier device

[0098] 17 generator device

[0099] 18 tank

[0100] 19 tank

[0101] 20 pump

[0102] 21 dispenser

[0103] 22 return line

[0104] 23 control unit

Claims

CLAIMS1 . A storage system (1) for biofuel storage comprising: a first tank (2) configured to contain the biofuel; a thermal conditioning unit (3) configured to maintain the biofuel that is inside the first tank (2) at a desired temperature; a delivery unit (6) configured to draw biofuel that is inside the first tank (2) to supply the biofuel to a tank of an external user device; and an atmosphere conditioning unit (4) configured to maintain a controlled atmosphere; and / or an additivation unit (5) configured to add at least one additive to the biofuel; the storage system (1) is characterized in that: the atmosphere conditioning unit (4) is configured to maintain a controlled atmosphere inside the first tank (2); and the additivation unit (5) is configured to add the additive to the biofuel that is inside the first tank (2).

2. The storage system (1) according to claim 1 , wherein: the thermal conditioning unit (3) comprises a conditioning hydraulic circuit (7) in which a thermal fluid flows that can be heated or cooled to heat or cool the biofuel that is inside the first tank (2); the conditioning hydraulic circuit (7) comprises a first heat exchanger (8) that is arranged inside the first tank (2) and performs a thermal exchange between the thermal fluid that is circulated inside the first heat exchanger (8) and the biofuel that is inside the first tank (2); the conditioning hydraulic circuit (7) comprises a second heat exchanger (9) that is arranged outside the first tank (2) and performs a thermal exchange between the thermal fluid that is circulated inside the second heat exchanger (9) and the biofuel that is circulated outside the first tank (2); and the two heat exchangers (8, 9) are usable alternatively to operate one at a time or in combination to operate simultaneously.

3. The storage system (1) according to claim 2, wherein the conditioning hydraulic circuit (7) comprises: a first pump (14) configured to circulate the thermal fluid through the first heat exchanger (8); and a second pump (15) which is separate and independent from the first pump (14) and is configured to circulate the thermal fluid through the second heat exchanger (9), so that by activating the first pump (14) the thermal fluid circulates through the first heat exchanger (8) and by activating the second pump (15) the thermal fluid circulates through the second heat exchanger (9).

4. The storage system (1) according to claim 2 or 3, wherein the thermal conditioning unit (3) comprises a circulation hydraulic circuit (10) that is configured to circulate the biofuel that is inside the first tank (2) through the second heat exchanger (9) and comprises a third pump (11) that can be activated to circulate the biofuel along the circulation hydraulic circuit (10).

5. The storage system (1) according to claim 2, 3 or 4, wherein the conditioning hydraulic circuit (7) comprises a heating device (12) configured to heat the thermal fluid that flows along the conditioning hydraulic circuit (7) and, preferably, a conditioning device (13) that is installed in parallel to the heating device (12) and is configured to heat or cool the thermal fluid that flows along the conditioning hydraulic circuit (7).

6. The storage system (1) according to one of claims 1 to 5, wherein the atmosphere conditioning unit (4) comprises a dehumidifier device (16) configured to generate dry air and to introduce the dry air in an upper part of the tank (2) not occupied by the biofuel.

7. The storage system (1) according to one of claims 1 to 6, wherein the atmosphere conditioning unit (4) comprises a nitrogen generator (17) configured to separate nitrogen from dry air and to introduce the nitrogen in an upper part of the tank (2) not occupied by the biofuel.

8. The storage system (1) according to one of claims 1 to 7, wherein the atmosphere conditioning unit (4) comprises a second tank (18) containing an inert gas and is configured to introduce the inert gas in an upper part of the tank (2) not occupied by the biofuel.

9. The storage system (1) according to one of claims 1 to 8, wherein: the atmosphere conditioning unit (4) is configured to increase an internal pressure of the first tank (2) so as to confer on the first tank (2) an internal pressure higher than atmospheric pressure; and a control unit (23) is provided configured to increase the internal pressure of the first tank (2) so as to reduce a solidification temperature of the biofuel.

10. The storage system (1) according to one of claims 1 to 9, wherein the additivation unit (5) comprises a third tank (19) containing an additive and a pump (20) that can be activated to draw the additive from the third tank (19) and to supply the additive into the first tank (2) or to supply the additive into the delivery unit (6).

11. The storage system (1) according to claim 10, wherein: the additive is a fossil fuel; and a control unit (23) is provided configured to maintain inside the first tank (2) a mixture of the biofuel and the fossil fuel having a predetermined composition.

12. The storage system (1) according to one of claims 1 to 1 1 and comprising a circulation hydraulic circuit (10) that is configured to draw a part of the biofuel that is inside the tank (2) from at least one extraction point, circulate the biofuel outside the tank (2), and then reintroduce the biofuel into the tank (2) in at least one return point different and separate from the extraction point.

13. The storage system (1) according to claim 1 , wherein: the thermal conditioning unit (3) comprises a conditioning hydraulic circuit (7) in which a thermal fluid flows that can be heated or cooled to heat or cool the biofuel that is inside the first tank (2); and the conditioning hydraulic circuit (7) comprises a single heat exchanger (9) that is arranged outside the first tank (2) and performs a thermal exchange between the thermal fluid that is circulated inside the heat exchanger (9) and the biofuel that is circulated outside the first tank (2).

14. A storage method for biofuel storage and comprising the steps of: supplying biofuel into a tank (2); maintaining the biofuel that is inside the tank (2) at a desired temperature by means of a thermal conditioning unit (3); supplying the biofuel that is inside the tank (2) to a tank of an external user device by means of a delivery unit (6); maintaining a controlled atmosphere by means of an atmosphere conditioning unit (4); and / or adding at least one additive to the biofuel by means of an additivation unit (5);the storage method is characterized by the fact that: the atmosphere conditioning unit (4) maintains a controlled atmosphere inside the first tank (2); and the additivation unit (5) adds the additive to the biofuel that is inside the first tank (2).

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