WO2025195607A1

WO2025195607A1 - Systems and methods for producing hydrogen gas by reacting silicon and water

Info

Publication number: WO2025195607A1
Application number: PCT/EP2024/057798
Authority: WO
Inventors: Martin Larsson
Original assignee: Energy Carrier Solutions Sarl
Current assignee: Energy Carrier Solutions Sarl
Priority date: 2024-03-22
Filing date: 2024-03-22
Publication date: 2025-09-25
Anticipated expiration: 2026-09-22

Abstract

A system for producing hydrogen gas by reacting silicon and water, comprises a reaction chamber, a water supply device, configured for supplying water to the reaction chamber, a silicon supply device, configured for supplying silicon to the reaction chamber, a hydrogen collection arrangement, configured for collecting hydrogen gas from the reaction chamber and supplying said hydrogen gas via a main output channel to an application hydrogen consumer, and a controller, configured to control at least one of the water supply device, the silicon supply device and the hydrogen collection arrangement. The disclosure provides a system and methods for producing hydrogen gas by reacting silicon and water. The disclosure further provides a vehicle comprising said system and a portable device comprising said system.

Description

SYSTEMS AND METHODS FOR PRODUCING HYDROGEN GAS BY REACTING SILICON AND WATER

Technical field

The present disclosure relates to systems and methods for producing hydrogen gas by reacting silicon and water.

Background

The concept of producing hydrogen gas by reacting silicon and water in a reaction chamber and collecting the thus produced hydrogen gas is well known.

Examples of systems and methods for this purpose are disclosed in WO2022242643, W02020245720, US2005042165, US2016046486, KR20130033844 and JP2000191303.

However, these systems and methods are still on a laboratory-stage, or, at best, on a demonstrator-stage, and they are still far from practically and/or commercially viable.

There is a need for improved systems and methods for producing hydrogen gas by reacting silicon and water. In particular, there is a need for systems and methods which are more efficient, which require the use of less hazardous or otherwise difficult to handle chemicals and which can be implemented as autonomous systems, in the sense that that they can be used on a mobile platform and/or without being connected to mains supplies of electric power and/or water.

Summary

It is a general objective of the present disclosure to provide solutions, such as systems and methods, for producing hydrogen gas by reacting silicon and water, which overcome, or at least alleviate, disadvantages of prior art systems. Particular objectives include the provision of systems and methods which are more efficient and/or more user friendly. Further objectives include the provision of systems and methods that can be implemented in an autonomous form.

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. According to a first aspect, there is provided a system for producing hydrogen gas by reacting silicon and water, comprising a reaction chamber, a water supply arrangement, configured for supplying water to the reaction chamber, a silicon supply arrangement, configured for supplying silicon to the reaction chamber, a hydrogen collection arrangement, configured for collecting hydrogen gas from the reaction chamber and supplying said hydrogen gas via a main output channel to an application hydrogen consumer, and a controller, configured to control at least one of the water supply arrangement, the silicon supply arrangement and the hydrogen collection arrangement.

A water supply arrangement may, for a fixed installation application, comprise a connection to a water mains supply, which may be controllable by a valve, or the like that may be controllable by a controller.

The water supply arrangement may, for a mobile application, comprise a water tank and a pump and/or a valve, or the like, that may be controllable by a controller.

A silicon supply arrangement may comprise a device that is configured to feed silicon in a controlled manner to the reaction chamber. The silicon may be fed as a loose powder or as one or more bodies that are readily dissolved when contacting the water. A controller may control a feed conveyor mechanism and/or a feed valve, or the like.

The hydrogen collection arrangement may comprise a connection for evacuating hydrogen gas from the reaction chamber. Optionally, the hydrogen collection arrangement may also comprise a hydrogen conditioning device, such as a gas dryer and/or a gas scrubber, a compressor and/or a storage tank, with valves that may be controllable by the controller.

The application hydrogen consumer may comprise any type of hydrogen consumer, including, but not limited to, a fuel cell, a hydrogen internal combustion engine or a hydrogen consuming process, such as an etching process or a metal direct reduction process.

The system may further comprise at least one hydrogen vent device, configured for ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and an auxiliary fuel cell, configured to receive and operate based on said ventilated hydrogen gas. A hydrogen vent device may be provided on the reaction chamber or anywhere in the hydrogen collection arrangement, on conduits in which hydrogen gas is conveyed or on vessels in which hydrogen gas is stored. For example, the vent device may take the form of a valve that is configured to release hydrogen gas to a vent line in the event of a hydrogen gas pressure exceeding a predetermined value.

The auxiliary fuel cell may be configured such that it has capacity to provide the necessary electric energy for operation of the system for producing hydrogen gas, excluding the application hydrogen consumer. Moreover, the auxiliary fuel cell may be operated only using the ventilated hydrogen gas.

By collecting also ventilated hydrogen gas and supplying it to the auxiliary fuel cell, it is possible to increase efficiency of the system.

To this end, one or more hydrogen vent lines may need to be provided, connecting the respective vent point directly to the auxiliary fuel cell or to an intermediate storage tank.

The system may further comprise an electrolysis device for generating hydrogen gas and oxygen gas by electrolysis of water.

The auxiliary fuel cell is configured to provide electric energy to power said electrolysis device.

The electrolysis device may be configured for feeding hydrogen gas to the auxiliary fuel cell and/or to the application hydrogen consumer.

The electrolysis device may be configured for feeding oxygen gas to the application hydrogen consumer.

The system may further comprise an electric energy buffer, such as a battery or a capacitor.

The electric energy buffer may be configured to provide power to at least one of the water supply arrangement, the silicon supply arrangement, the controller and the agitation device, if any.

The electric energy buffer may thus be configured only to provide electric power to internal functions of the system, such as a controller, an agitator, valves or other mechanisms for feeding materials to the reaction chamber, and/or an electrolysis device, if any, but not to the application hydrogen consumer.

Hence, an essentially self-sufficient system is provided. The auxiliary fuel cell, if any, may be configured to provide electric energy for storage in said electric energy buffer.

The system may further comprise at least one agitation device for agitating reagents in the reaction chamber.

The auxiliary fuel cell, if any, may be configured to provide electric energy for powering the agitation device.

The agitation device may comprise a first ultrasonic actuator which is provided in a lowermost portion of the reaction chamber.

An agitation device in the form of an ultrasonic actuator can be made compact and durable, while still being highly efficient in causing agitation of the water and unreacted silicon and optionally also efficient in removing any oxide layer from the silicon so as to expose an unreacted silicon surface, thus preventing the hydrogen production from subsiding while there is still unreacted silicon in the reaction chamber.

The agitation device may comprise a rod extending upwardly from a bottom portion, in particular from a lowermost portion of the bottom portion, of the reaction chamber.

The agitation device may comprise a plate forming at least part of a surface in the reaction chamber for supporting wholly or partially reacted silicon.

The system may further comprise a mechanical agitator, configured to mechanically agitate, in particular stir, silicon and/or silicon oxide particles deposited on or near a bottom portion of the reaction chamber.

The system may further comprise at least one second ultrasonic actuator, which is spaced from a bottom of the reaction chamber, the second ultrasonic actuator comprising at least one sonicator probe, and a particle separator, wherein the sonicator probe is configured to agitate particles present on the particle separator, and wherein the particle separator is configured to allow particles smaller than a predetermined size to pass.

The particle separator can be used to ensure that unreacted particles are treated optimally, as there is a possibility to treat larger and smaller particles with different agitator parameters.

The system may comprise at least two said sonicator probes, which are positioned at different distances from a bottom of the reactor chamber. The system may comprise at least two said particle separators, which are positioned at different distances from the bottom region of the reactor chamber.

A bottom portion of the reaction chamber may be inclined towards the lowermost portion of the reaction chamber.

The system may further comprise a thermoelectric generator ("TEG"), thermally coupled to the reaction chamber so as to receive heat from the reaction chamber.

The thermoelectric generator may be configured to supply electric energy to at least one of the electric energy buffer, if any, the electrolysis device, if any, and the agitation device, if any.

By using a TEG to produce electricity, it is possible to cool the reaction chamber, e.g. to reduce the risk of over-heating, and to provide electricity for powering the system.

The electric energy buffer may be configured to power only internal functions of the system, such as a controller, an agitator, valves or other mechanisms for feeding materials to the reaction chamber, and/or an electrolysis device, if any.

The reaction chamber may present a reaction chamber wall defining a reaction space and an outer wall, which encloses at least part of the reaction chamber wall, wherein the thermoelectric generator is thermally coupled to the reaction chamber wall.

The system may further comprise a cooling medium provided in a space formed between the reaction chamber wall and the outer wall.

The cooling medium may be a gas, such as air, or a liquid, such as water.

The system may further comprise an actuator configured to drive the cooling medium through the space.

The system may further comprise an application comprising at least one application hydrogen consumer, an electric energy buffer, such as a battery or a capacitor, and a thermoelectric generator, thermally coupled to the application hydrogen consumer so as to receive heat from the application hydrogen consumer. The thermoelectric generator may be configured to supply electric energy to the electric energy buffer and/or to an electric energy buffer configured for powering the application. The system may further comprise at least one component that generates residual water, and a water return device for returning said residual water to the water supply arrangement or to the reaction chamber.

At least some of the residual water may be generated by dewatering and drying residual silicon material. At least some of the residual water may be generated by drying the generated hydrogen gas. At least some of the residual water may be generated by the auxiliary fuel cell or by an application comprising a fuel cell and/or a combustion engine.

The component that generates residual water may comprise a condenser unit.

The condenser unit may be connected to receive water vapor from at least one of a slurry dryer, an auxiliary fuel cell, and the application hydrogen consumer.

The component that generates residual water may comprise a first separator unit for separating solid material from a liquid.

The first separator may be a filter, a centrifuge device, a decantation device, an evaporation device, a dryer, or the like.

The first separator may be used to provide a solid, and optionally dry, residual product comprising silicon dioxide formed in the reaction chamber.

The system may further comprise a second separator (302) for separating at least one solid material from at least one further solid material.

The second separator (302) may be used to separate out e.g. the silicon dioxide from other oxides and/or contaminants so as to increase purity of the silicon dioxide and thus enhance its recyclability.

The system may further comprise a mechanical grinding device configured for grinding the silicon into particles, wherein the grinding device is arranged inside the reaction chamber and configured to utilize the water as grinding liquid

The grinding device may be configured to grind the silicon into particles having a particle size less than about 500 pm, less than about 250 pm, less than about 100 pm, preferably less than about 50 pm, less than about 25 pm, less than about 10 pm, less than about 1 pm, less than about 500 nm, less than about 100 nm, less than about 50 nm, less than about 25 nm or less than about 10 nm.

The system may further comprising a catalyst, provided inside the reaction chamber. A catalyst may be provided as a coating, e.g. on the reaction chamber wall, on one or more items present in the reaction chamber, such as agitation devices, and/or on/in pellets provided inside the reaction chamber. Such pellets may be porous to provide a large catalyst-coated surface.

The system may further comprise a pH sensor configured to detect a pH in the reaction chamber and to supply a corresponding signal to the controller, and a pH adjusting device, which is controllable by the controller and configured to provide at least one non-toxic pH adjustment agent to the reaction chamber.

The system may further comprise an electrolysis device configured to receive water from the water supply arrangement and to supply hydrogen gas to the hydrogen collection arrangement.

The electrolysis device may be configured for receiving electric power from an auxiliary fuel cell and/or from an energy buffer and/or from a TEG.

The electrolysis device can be used to convert excess electric power from the energy buffer into hydrogen gas.

The system may further comprise an oxygen collection device, configured to receive oxygen gas from the electrolysis device and for supplying the oxygen gas to the application hydrogen consumer and/or to the auxiliary fuel cell.

By also collecting oxygen gas and supplying the oxygen gas to one of the fuel cells, it is possible to increase efficiency of the fuel cell(s).

The system may further comprise at least one hydrogen vent device, configured for ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and a channel connecting the hydrogen vent device to the application hydrogen consumer for feeding ventilated hydrogen to said application hydrogen consumer.

The application hydrogen consumer may be a fuel cell or an internal combustion engine.

The system may further comprise a thermoelectric generator, thermally coupled to the application hydrogen consumer so as to receive heat from the application hydrogen consumer, the thermoelectric generator configured to supply electric energy to the electric energy buffer and/or to an electric energy buffer configured for powering the application. The system may further comprise at least one airlock, wherein at least one of the silicon supply arrangement and an additive is configured to feed to the reaction chamber through said airlock.

It is understood that feeding "through the airlock" can take place by the entire feed mechanism being placed inside, or integrated with, the airlock, or by first feeding its material from the surrounding to the inside of the airlock, after which the airlock is closed to the outside and the material is fed from inside the airlock to the reaction chamber.

The additive may be any additive, including, but not limited to, a pH adjustment agent.

Use of an airlock for feeding materials facilitates continuous operation of the system.

The system may be mounted on a mobile or portable platform.

According to a second aspect, there is provided a vehicle, comprising a vehicle frame, an electric power storage device, an electric drive motor, connected to the electric power storage device and configured to propel the vehicle, and a system as described above, supported by the vehicle frame and configured to provide electric power to the electric power storage device and/or to the drive motor.

The vehicle may be an automobile, a motorcycle, a moped, a boat, a fixed wing aircraft or a rotary wing aircraft.

According to a third aspect, there is provided a portable device, comprising a device frame, an electric output connector, optionally an electric power storage device, configured to provide electric power to the electric output connector, and a system as described above, supported by the device frame and configured to provide electric power to the electric output connector and/or to the an electric power storage device.

The electric output connector may be configured as a standardized mains outlet connector.

The portable device may further comprise a housing enclosing the system, wherein the an electric output connector is accessible from outside the housing.

According to a fourth aspect, there is provided method for producing hydrogen gas by reacting silicon and water, comprising supplying water to a reaction chamber, supplying silicon to the reaction chamber, collecting hydrogen gas from the reaction chamber and supplying said hydrogen gas via a main output channel to an application hydrogen consumer, and wherein a controller is used control at least one of said supply of water, said supply of silicon and said collection of hydrogen gas.

The method may further comprise using at least one thermoelectric generator to generate electric power from thermal energy received from the reaction chamber, storing said electric power in an electric energy buffer, and supplying said electric power to power at least one of the controller, the supply of water, the supply of silicon and the collection of hydrogen gas.

The method may further comprise ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, collecting said ventilated hydrogen gas, feeding said ventilated hydrogen gas to an auxiliary fuel cell, and using the auxiliary fuel cell generate electric power, storing said electric power in an electric energy buffer, and supplying said electric power to power at least one of the controller, the supply of water, the supply of silicon and the collection of hydrogen gas.

The method may further comprise generating hydrogen gas and oxygen gas by electrolysis of water in an electrolysis device, wherein said electrolysis device is powered by the electric power.

The method may further comprise collecting oxygen gas from the electrolysis device and supplying the oxygen gas to the application hydrogen consumer and/or to the auxiliary fuel cell, if any.

The method may further comprise using a thermoelectric generator, which is thermally coupled to an application hydrogen consumer, to generate electric power, storing said electric power in an electric energy buffer, and supplying said electric power to power at least one of the controller, the supply of water, the supply of silicon and the collection of hydrogen gas.

The method may further comprise agitating the water and silicon present in the reaction chamber using at least one agitation device.

The method may comprise using at least one first ultrasonic actuator to agitate silicon in a bottom region of the reaction chamber. The method may comprise using at least one second ultrasonic actuator to agitate silicon in a region spaced from the bottom region of the reaction chamber.

The method may comprise selectively retaining silicon in the region spaced from the bottom region of the reaction chamber while agitated by the second ultrasonic actuator.

The method may comprise detecting an indication of a hydrogen production rate in the reaction chamber, and varying operation of at least one of the first ultrasonic actuator and the second ultrasonic actuator in response to said indication.

The method may comprise supplying the silicon to the reaction chamber having a first particle size, and using the agitation device(s) to reduce the first particle size to a second, smaller particle size.

The method may comprise providing the silicon having a particle size of about 0.1-5 mm, preferably about 0.1-2 mm or about 0.1-1 mm, mechanically reducing particle size of the silicon into smaller silicon particles, wherein said mechanically reducing particle size is performed inside the reaction chamber with water present in the reaction chamber as grinding liquid, and collecting hydrogen gas formed during said grinding.

Said silicon particles may be reduced into silicon particles having a particle size less than about 500 pm, less than about 250 pm, less than about 100 pm, preferably less than about 50 pm, less than about 25 pm, less than about 10 pm, less than about 1 pm, less than about 500 nm, less than about 100 nm, less than about 50 nm, less than about 25 nm or less than about 10 nm.

The method may further comprise generating residual water and returning at least some of said residual water to the reaction chamber.

Said generating residual water may comprise condensing water vapor.

Said generating residual water may comprise separating a solid material from a liquid.

The method may further comprise separating at least one solid material from at least one further solid material.

The method may further comprise sensing a pH value in the reaction chamber and supplying at least one, preferably non-toxic, pH adjusting agent to the reaction chamber. The method may further comprise ventilating at least some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and feeding ventilated hydrogen to said application hydrogen consumer.

The method may further comprise using at least one electric energy generating component to generate electric power from thermal energy received from the application hydrogen consumer, storing said electric power in an electric energy buffer, and supplying said electric power to power at least one of the controller, the supply of water, the supply of silicon, the collection of hydrogen gas and the application hydrogen consumer.

The method may comprise providing the silicon as powder in an enclosed capsule, which is formed from a metallic material, in particular aluminum, opening the capsule, feeding the metal powder from the capsule to the water, mechanically converting the capsule into metallic capsule powder, and allowing the metallic capsule powder to react with the water to form hydrogen gas.

The silicon may comprise scrap silicon from used semiconductor devices.

The method may further comprise providing at least one catalyst in the reaction chamber.

According to a fifth aspect, there is provided a method of providing power to a mobile or portable platform, comprising the method described above.

In the method, at least one of the silicon and the pH adjustment agent may be fed to the reaction chamber through an airlock.

Fig. 1 schematically illustrates a system for producing hydrogen gas by reacting silicon and water.

Fig. 2 schematically illustrates a process flow in the system.

Fig. 3 schematically illustrates an alternative process flow in the system.

Fig. 4 schematically illustrates an alternative embodiment of the agitation device.

Fig. 5 schematically illustrates a modification of the system for producing hydrogen gas by reacting silicon and water.

Fig. 6 schematically illustrates a further modification of the system for producing hydrogen gas by reacting silicon and water. Fig. 7 schematically illustrates a standalone device for supplying electricity.

Fig. 8 schematically illustrates a cross sectional view from above of a reaction chamber.

Figs 9a-9b schematically illustrate an airlock for a feed mechanism.

Detailed description

Fig. 1 schematically illustrates a system for producing hydrogen gas by reacting silicon and water in a reaction chamber 120, which encloses a reaction space. The system may be controlled by a controller 600, which may be a central controller or a plurality of controllers which may operate more or less individually or in a coordinated manner.

The controller (or controllers, as the case may be) may be configured to control all aspects of the system, including supply of various materials (water, silicon, pH adjustment agents, etc.), pressures, temperatures and other operating parameters, such as agitation.

In the following, reference will be made to silicon, although it is understood that aluminum can be used instead of, or together with, silicon.

The system comprises a silicon supply arrangement 100, which, in some embodiments may comprise a capsule feed device 101 and, in some embodiments, a grinding device 102 for reducing the size of silicon that is being fed to the system.

In embodiments where silicon is supplied in a sufficiently fine powder state, such a nanopowder or micropowder, or where other means for reducing the size of silicon particles are provided, no grinding device may be needed.

Such fine powder may be supplied in hermetically enclosed capsules, which may enclose the silicon powder in a vacuum or sufficiently inert environment.

In other embodiments, where the silicon may be supplied in larger particles, or even as silicon scrap, the grinding device 102 may be arranged to reduce the size of the silicon particles so as to enable the reaction with water.

The silicon supply arrangement 100 and in particular the capsule feed device 101, the grinding device 102 and/or the valve 1021 may be controlled by the controller 600.

In the event the capsule is produced from a material, such as aluminum, that when reacted with water can cause production of hydrogen gas, such capsule may be grated or ground into powder of a suitable particle size and thus used as additional fuel.

A valve 1021, or similar functional structure, may be provided to control the supply of silicon into the reaction chamber 120.

The silicon provided to the reaction chamber 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.

However, the silicon provided to the reaction chamber 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.

The silicon provided to the reaction chamber may be provided in the form of a silicon 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, 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.

In some embodiments, the silicon may be provided in the form of a powder having greater powder size. In particular, the silicon may be provided with a particle size of about 1-5 mm. Such embodiments may require a mechanical grinding device to be used to convert the silicon particles into smaller silicon particles.

In other embodiments, the silicon may be provided with a particle size of about 500 nm-1000 nm or about 1-1000 pm. Such embodiments may also require a mechanical grinding device to be used to convert the silicon particles into smaller silicon particles.

In some embodiments, the silicon may be provided in the form of recycled silicon from discarded or damaged semiconductor devices, in particular semiconductor based photovoltaic cells, i.e. solar panels. Such silicon may be ground or grated into particles or shards, which can be fed to the reaction chamber, either directly, or via a grinding device. Such shards should preferably be of a particle size less that 1 mm, preferably less than 1 pm. In yet further embodiments, some or all of the silicon may be replaced with aluminum, which can provide a similar reaction with water.

In some embodiments, the mechanical grinding device may be sufficient to provide silicon particles with a particle size that is so small as to allow for essentially complete reaction of all silicon.

The system further comprises a water supply arrangement 110, which may comprise a water tank 111 and/or a water mains connection. A valve 1111 may be provided for controlling the supply of water to the reaction chamber 120.

The water supply arrangement 110 may be connected to a water recycling arrangement which will be described below.

The water supply arrangement 110, in particular the valve 1111 and/or any pump (not shown) provided to feed water, may be controlled by the controller 600.

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

The system further comprises a hydrogen gas collection arrangement, which may include one or more storage tanks 170, channels 171, 206 and valves 172, 173, 174 which control the flow of hydrogen gas from the reaction chamber 120 via a main output channel 171 to storage tanks 170, applications or to any auxiliary device utilizing hydrogen gas.

The system may further include an auxiliary fuel cell 901, i.e. a fuel cell which is configured to convert hydrogen gas into electric power, which may be stored in one or more electric energy buffers 902, 903 that is/are provided for supplying electric power for the operation of the system, but not of any external application. The auxiliary fuel cell is sized and adapted to supply electric power to operate the system, but not any external application. The electric energy buffer(s) may be provided in the form of one or more batteries or capacitors.

A hydrogen vent device may be provided, comprising the valves 172, 173, 174 and channels 171, 206, which may include one or more vent valves configured to release hydrogen gas in the event of excess pressure detected in the system. Such vent valves may be integrated with control valves and/or non-return valves. The vent valves may be connected by pipes or hoses to the auxiliary fuel cell 901.

While hydrolysis is a highly efficient and sustainable method of generating hydrogen, it is desirable to have appropriate safety measures in place, including the ventilation of hydrogen gas and in the present case to harvest this normally ventilated energy. The ventilated gas may be moved to an auxiliary fuel cell and used to generate electricity to the energy buffers in the system.

The specific part of the system where hydrogen is ventilated can vary depending on the design and configuration of the unit.

In some cases, there may be dedicated ventilation pathways connected directly to the reaction chamber module. These pathways allow for the safe release of hydrogen gas to the auxiliary hydrogen fuel cell, reducing the risk of any potential buildup within the system.

Additionally, hydrogen storage tanks, which are often used to store the produced hydrogen gas, may also have ventilation mechanisms. These tanks can be equipped with vents or exhausts that allow for the safe release of any excess hydrogen gas and in the present case sending that ventilated hydrogen gas to the auxiliary fuel cell to create electricity instead. Proper ventilation in hydrogen storage tanks ensures that hydrogen levels remain within safe limits, reducing the potential for accidents or explosions.

Hence, electric power generated by the auxiliary fuel cell 901 and stored in the electric energy buffers 902, 903 may be used to power functions such as the controller 600, agitation devices 300 for agitating the reagents present in the reaction chamber and feed arrangements 100, 110 for water and silicon.

Optionally, the auxiliary fuel cell 901 may be fed hydrogen from the hydrogen collection arrangement, or from the hydrogen storage tank 170.

There may also be provided a thermoelectric generator ("TEG") 904 for conversion of thermal energy generated in the reaction chamber 120 into electric energy that can be stored in the electric energy buffers 902, 903 and/or used to power the system.

TEGs are devices that convert heat energy directly into electrical energy using the Seebeck effect, which is the phenomenon where a temperature difference across a material generates an electric voltage. There are several types of thermoelectric generators, each with its own design and application:

Bulk Thermoelectric Generators: These are the most common type of TEGs and are made from bulk thermoelectric materials, typically semiconductors such as bismuth telluride (Bi2Te3) or lead telluride (PbTe). Bulk TEGs consist of thermoelectric modules connected electrically in series and thermally in parallel. They are used in various applications, including waste heat recovery, automotive exhaust systems, and portable power generation.

Thin-Film Thermoelectric Generators: Thin-film TEGs are fabricated using thin-film deposition techniques such as sputtering or chemical vapor deposition. These TEGs offer advantages such as flexibility, lightweight, and potential for integration into flexible or curved surfaces. They are used in applications where space and weight constraints are critical, such as wearable electronics, medical devices, and loT sensors.

Nanostructured Thermoelectric Generators: Nanostructured TEGs are based on thermoelectric materials with nanostructured features, such as nanowires, nanotubes, or nanocomposites. These nanostructures can enhance the thermoelectric properties of the material, leading to improved efficiency and performance. Nanostructured TEGs have potential applications in high-performance cooling systems, microelectronics, and space missions.

Quantum Dot Thermoelectric Generators: Quantum dot TEGs utilize quantum dots, which are nanoscale semiconductor particles, as the active material for thermoelectric conversion. Quantum dots exhibit unique electronic properties that can be tailored for specific thermoelectric applications. Research in this area focuses on improving the efficiency and scalability of quantum dot TEGs for energy harvesting and power generation.

Thermophotovoltaic Generators: Thermophotovoltaic (TPV) generators convert heat energy into electricity using a combination of thermal radiation and photovoltaic cells. A high-temperature heat source emits photons, which are absorbed by a photovoltaic cell to generate electricity. TPV generators can achieve high conversion efficiencies, especially at high temperatures, and are used in applications such as remote power generation, space exploration, and waste heat recovery. One or more TEGs may be thermally coupled to any component in the system generating a sufficient amount of heat, including the reaction chamber 120, the auxiliary fuel cell 901 and the application hydrogen consumer.

A TEG may require a suitable DC/DC converter to provide a sufficient voltage that can be supplied to an energy buffer 902, 903 or otherwise be made useful.

Such TEGs may be connected to the energy buffers 902, 903 of the system or to a separate energy buffer forming part of the application.

The system may further comprise an electrolysis device 400 configured to use electric power from the auxiliary fuel cell 901 and/or from the electric energy buffers 901, 902 to convert water into hydrogen gas and oxygen gas. The hydrogen gas may be conveyed to the hydrogen storage tank 170. The oxygen gas may be collected by an oxygen collection device, which may comprise one or more pipes, valves and optionally a gas dryer, and conveyed to an oxygen tank 401 through a conduit 402 and one or more valves 403. Oxygen gas may be fed to the application and/or to the auxiliary fuel cell 901.

The system may further comprise an agitation device utilizing ultrasound to cause cavitations in the reaction chamber so as to agitate reagents and to break up any oxide layer formed on silicon particles present in the reaction chamber 120.

The agitation device may comprise one or more first ultrasonic actuators, which may comprise drive units 122 and one or more probes 1221, which may extend into the reaction chamber 120, preferably from a lowermost portion 121 of the reaction chamber 120. Such agitation devices are known as such and are often referred to as "sonicators".

It is well known per se that ultrasound can be used to reduce the particle size of a metal in water through a process known as ultrasonic cavitation. When high- intensity ultrasound waves are applied to a liquid, they create alternating high- pressure and low-pressure cycles. During the low-pressure cycles, small vacuum bubbles or voids form in the liquid due to the reduction in pressure. When the pressure increases again during the high-pressure cycles, these bubbles collapse violently in a process called cavitation.

During cavitation, the collapse of these bubbles generates very high temperatures and pressures locally, leading to the formation of shockwaves and microjets. These extreme conditions can cause the fragmentation and breakdown of metal particles suspended in the liquid, leading to a reduction in particle size.

This technique is often used in various fields, including materials science, nanotechnology, and metallurgy, to produce fine metal powders or nanoparticles with controlled properties. Ultrasonic cavitation offers advantages such as scalability, relatively low cost, and the ability to produce particles with narrow size distributions.

There are various types of sonicators available, some of which will be mentioned below.

Bath Sonicators: These are benchtop devices that consist of a tank filled with a liquid medium (usually water) into which the sample is immersed. Ultrasonic waves are generated by transducers mounted at the bottom of the tank, and the sample is treated as it is submerged in the liquid.

Probe Sonicators: Also known as handheld or tip sonicators, probe sonicators consist of a handheld probe or horn that is immersed directly into the sample. The ultrasonic waves are generated at the tip of the probe, allowing for localized treatment of the sample.

Flow Cell Sonicators: These sonicators are designed for continuous flow applications. The sample flows through a narrow channel or tube, and ultrasonic waves are applied to the sample as it passes through the flow cell.

Microplate sonicators: Also known as a microplate ultrasonic homogenizer or microplate ultrasonic processor, is a laboratory instrument used for the simultaneous disruption, homogenization, and mixing of samples in microplate wells.

Ultrasonic Processors: These are larger-scale sonication systems used in industrial settings. They typically consist of a generator that produces ultrasonic waves and a horn or probe that transmits the waves to the sample. Ultrasonic processors can handle larger volumes and are suitable for high-throughput applications.

Operating parameters of the sonicator may be selected for achieving a cleaning action on the silicon particles, whereby any oxide layer formed on a silicon particle is removed to expose silicon that can react with the water. It is possible to also provide one or more mechanical agitators, in particular operating at the bottom region of the reaction chamber 120.

The system may further comprise an oxide recovery device 300, which may be connected to the lowermost portion 121 of the reaction chamber 120 to remove the residual product which is formed as a slurry. The oxide recovery device 300 may comprise a first separator unit 301 that is configured to separate solid matter from the slurry and collect water for recycling, either directly via valves 202, 205 and conduits 201 to the reaction chamber 120 or via the water supply arrangement 110.

In the case where more than one metal is used in the system (e.g. aluminum and silicon), it may be necessary to separate different oxides.

To this end, the system may further comprise a second separator unit 302, configured to separate the solid matter into two or more fractions, which may enhance recycling, e.g. by improving the purity of at least one fraction.

Such a second separator unit 302 may be integrated in the system, e.g. on a mobile or portable platform, or it may be provided as a separate unit, which is connectable to the first separator unit, such that residual solid matter may be transferred for separation.

The second separator unit 302 may, as non-limiting examples, make use of one or more of the following techniques.

Gravity Separation: As aluminum oxide is significantly denser than silica, it is possible to take advantage of gravity separation. By carefully pouring the mixture onto a slope or using a funnel with a filter, the heavier alumina will settle at the bottom while the lighter silica can be collected separately.

Magnetic Separation: If one of the components is magnetic, it is possible to use a magnet to separate the magnetic material (if present) from the non-magnetic material.

Differential Solubility: Silicon dioxide is not soluble in water while aluminum oxide can dissolve under certain conditions. It is possible to dissolve one component in a suitable solvent and then filter out the undissolved component.

Electrostatic Separation: This method utilizes the differences in electrostatic charges between the two substances. By applying an electric field, it is possible to separate them based on their electrostatic properties. Centrifugation: By spinning the mixture at high speed in a centrifuge, particles of different densities will separate based on their mass, allowing for easy separation.

Flotation: This method is based on the different hydrophobic properties of the components. One component is made hydrophobic and attaches to air bubbles, allowing it to float while the other component sinks.

The system may further comprise a water recycling arrangement comprising one or more of a slurry dryer for drying the oxide slurry and a gas dryer for drying the hydrogen gas generated in the reaction chamber 120 and/or in the electrolysis device 400. The gas dryer may comprise a condenser connected to the slurry dryer, to the auxiliary fuel cell 901 and/or to the gas dryer with a water return line for returning condensed water directly to the reaction chamber and/or to the water supply arrangement 110.

The water recycling arrangement may also be connected to the application such that water vapor generated in a hydrogen fuel cell or a hydrogen internal combustion engine can be condensed and recycled, either via a conduit 203 and valve 204 directly to the reaction chamber 120 or via the water supply arrangement 110.

The water recycling arrangement may be used to adjust pH in the reaction chamber, as recycled water, in particular recycled water from a condenser, can be expected to have a neutral pH of about 7.

To this end, the water recycling arrangement may be separated into two part, with one part recycling exclusively condensed water and the other part recycling water from a separator or dewatering device connected to the residue management device.

Alternatively, all water may be passed through a condenser arrangement so as to ensure a neutral pH.

The reaction chamber 120 may be provided with a residue level indicator 122 for indicating the amount of residues present at the lower portion of the reaction chamber 120.

The reaction chamber may be provided with a water level indicator 123 for indicating the amount of water present in the reaction chamber 120.

The indicators 122, 123 may be connected to the controller 600. In order to control the pH in the reaction chamber 120, it is possible to add one or more pH-increasing agents. Preferably, the agent should be non-toxic to at least human beings. Examples of such agents are sodium bicarbonate, calcium hydroxide and calcium carbonate, each of which may be powderized.

The pH-increasing agent may be supplied in solid or liquid form. In particular, the pH-increasing agents may be supplied as part of the silicon supply, either by being individually controlled and supplied, or by being supplied proportionally with the silicon.

To this end, it is possible to further provide one or more pH adjustment agent supply devices.

For example, a pH lowering agent may be provided for controlled supply of at least one agent that has a pH lowering function. Preferably, the agent should be non-toxic to at least human beings. An example of such an agent is acetic acid, carbon dioxide, ascorbic acid or citric acid.

In some cases, it may be desirable to add a pH adjustment agent that may be toxic, such as sodium hydroxide.

The pH adjustment agent supply device(s) may be controlled by the controller 600, preferably in response to at least one pH sensor provided in the reaction chamber.

In the case of a solid pH adjusting agent, this may be supplied as a powder, a pelletized powder or in a capsule. The capsule may be either a non-water soluble capsule that is opened to allow evacuation of the powder or a capsule that dissolves in the water, such that the entire capsule may be fed to the reaction chamber.

The capsule may be produced from a non-toxic material, and in particular a material that does dissolves or melts when contacting water. Such materials are well known from the pharmaceutical industry. Potentially standard capsules may be used.

It is possible to provide a separate feeding mechanism for each type of capsule.

Hence, there may be provided e.g. a feed magazine, from which capsules may be individually fed to the reaction chamber.

Pelletized powder or capsules may be attached to a web, to be detached or opened in connection with being fed to the reaction chamber. Hence, such additive supply device may be provided as a separate supply device for capsules and/or powder, or integrated with the silicon supply device.

In particular, pH adjusting agent capsules may be smaller in terms of volume and/or wight than the silicon capsules.

Capsules may also be used for other additives than pH adjusting agents, which may be used to control or enhance the hydrolysis reaction.

By using an aerator, it is possible to use carbon dioxide present in ambient air to reduce pH by allowing air to bubble through the water present in the reaction chamber or in the water supply unit.

Fig. 2 schematically illustrates flows within the system disclosed in fig. 1.

Silicon is supplied to the reaction chamber 120 through the silicon supply arrangement 100 and water is supplied through the water supply arrangement 110. Optionally, auxiliary chemicals, such as pH adjusters, catalysts, or the like may be supplied through an auxiliary chemical supply 103.

Hydrogen is collected from the reaction chamber 120 and optionally stored in a hydrogen tank 170 for further supply to one or more applications 500. Vented hydrogen gas may be supplied to the auxiliary fuel cell 901, which, in turn, may supply electric energy to power the agitation arrangement 122.

Fig. 3 schematically illustrates flows within the system disclosed in fig. 1. In more detail. The energy buffer 902, 903, which may be embodied as one or more batteries, capacitors, or the like is used to supply electric energy to the system. The auxiliary fuel cell 901 provides electric energy to the energy buffer 902, 903, which may be used to drive the agitation arrangement 122, the controller, silicon supply arrangement 100, water supply arrangement 110, measurement sensors (not shown), control valves and the electrolysis chamber 400. The electrolysis chamber 400 may supply hydrogen gas to the auxiliary fuel cell 901 and oxygen gas to the application and/or to the auxiliary fuel cell 901.

Fig. 4 schematically illustrates an alternative reaction chamber 120, which corresponds to the one illustrated in fig. 1, with the modification that the first ultrasonic actuator comprises a sonicator probe 1222, which is provided to cover at least part, possibly all, of the bottom of the reaction chamber 120, such that any solids accumulating at the bottom of the reaction chamber 120 will rest on the sonicator probe 1222. Fig. 5 schematically illustrates yet an alternative reaction chamber 120, which corresponds to the one illustrated in fig. 1, with the modification that a grinding device 700, such as one or more ball mills, is provided in the reaction chamber and at least partially submerged in the water.

There are various types of ball mills, which are known per se, including:

Attrition Mill: Also known as the attritor or stirred ball mill. The balls are set in motion by rotation of the central shaft on which secondary arms are fixed. The cylinder itself is fixed.

Horizontal Mill: The cylinder rotates around its horizontal axis. The combined effects of the centrifugal force induced by this rotation and gravity cause the balls to rise and fall onto the powder particles.

ID Vibratory Mill: Also known as a shaker mill. The vessel is set in vertical oscillatory motion. Under this action, the 1-kg ball rises then falls back onto the powder particles.

Planetary Mill: The containers are fixed on a table which rotates until the centrifugal acceleration reaches 30 to 50 times the acceleration due to gravity. The containers themselves also rotate in modern mills, this rotation being either coupled or uncoupled with respect to the rotation of the table.

3D Vibratory Mill: Also known as a three-axis shaker. These operate according to the same principle as the ID vibratory mill, but this time in a more complex way due to the 3 vibrational degrees of freedom. The balls collide with the side walls of the container (friction and impacts), but also with its floor and ceiling.

The grinding device 700 may be configured to receive silicon that is fed into the reaction chamber 120 by the silicon supply arrangement 100, and reduce the size of the silicon particles thus received, using the water as a grinding fluid.

The reaction chamber illustrated with reference to fig. 5 may be equipped with an agitator as disclosed with reference to fig. 1 and/or fig. 4.

Fig. 6 schematically illustrates yet an alternative reaction chamber 120, which corresponds to the one illustrated in fig. 1, with the modification that a second sonicator assembly 800 is provided, comprising a second ultrasonic actuator, which may include at least one sonicator probe 801, 804 and at least one particle separator 802, 803, which is tuned to only allow passage of particles of a certain maximum size. The sonicator assembly 800 may be arranged in the reaction chamber 120 and spaced from the bottom portion 121 of the reaction chamber, such that the reaction and agitation of the silicon and residues is not impeded.

The sonicator assembly 800 may be configured to receive incoming silicon particles on an upper particle separator 802, where smaller particles are allowed to pass under the influence of gravity and larger particles are accumulated on the separator 802, such that they are subjected to ultrasonic treatment from the one or more sonicator probes 801, 804. The ultrasonic treatment causes oxides and other residues or impurities present on the surface of the silicon particles to separate from the silicon particles, such that exposed silicon can react with the water in the reaction chamber 120.

Optionally, two or more particle separators 802, 803 may be provided at different vertical levels and having, as seen in the downward direction, increasingly finer apertures, such that larger particles are treated at upper particle separators 802 and smaller particles are treated at lower particle separators 803.

Upper and lower sonicator probes 801, 804 may be operated at different frequencies, duty cycles, directions and/or amplitudes, so as to be optimized for the particles each sonicator probe 801, 804 is intended to treat.

The sonicator assembly 800 of fig. 6 may be combined with the embodiment of fig. 1, fig. 4 and/or fig. 5.

In particular, the sonicator assembly 800 may be positioned below a grinding arrangement 700 as illustrated in fig. 5.

The chemical reaction between the metal and water forms a passivating layer of oxide on the particles/shards surface and this layer acts as a protective barrier, preventing further reaction with the water. When this layer forms, the reaction slows down and eventually stops, halting the production of hydrogen gas.

The solution to the surface oxidation of the particles/shards in water is to use a low energy (in small bursts) cleaning technique specifically efficient in removing particle/shard oxidation surfaces. And there is actually no need to damage/split the particles/shards themself as we want the oxide removal only, this to make the chemical process not to be interupted by the oxide layer on the particles/shards. The thin oxide layer's limited thickness on the particles/shards reduces the depth of material that needs to be disrupted and removed, and this give as result a very low energy input requirement in the small sonicator bursts used by the system.

The oxide thickness on silicon particles depends on the particle diameter. There is a relationship between the size of the silicon particles and the thickness of the oxide layer that forms on them. For Silicon particles with sizes in the micron range (e.g., tens to hundreds of microns), the oxide layer thickness may typically range from a few nanometers to tens of nanometers. The oxide layer thickness would increase with larger particle sizes due to the increased surface area available for oxidation.

In normal air, the oxide layer on silicon particles tends to stabilize after initial formation. This oxide layer acts as a protective barrier against further oxidation of the underlying silicon material. Once the stable oxide layer forms, it typically prevents further significant growth or penetration of oxygen into the silicon particles.

When silicon particles with a stable oxide layer are placed in normal water, the oxide layer acts as a protective barrier that prevents direct contact between the silicon and water. Silicon dioxide (SiO2), which forms the oxide layer, is generally insoluble in water and provides resistance to chemical reactions with water. Therefore, the stable oxide layer would likely protect the silicon particles from reacting or dissolving in water.

The oxide layer on aluminum particles/shards in normal air is has a thickness ranging from a few to tens of nanometers, but it can vary depending on the size of the aluminum particles/shards.

When raw aluminum is exposed to air, a thin film of aluminum oxide forms on the surface of the aluminum particles/shards. This layer of aluminum oxide acts as a protective barrier that prevents further corrosion of the underlying aluminum.

The thickness of the aluminum oxide layer on aluminum particles in normal air can vary but typically ranges from a few nanometers to tens of nanometers. This oxide layer helps to shield the aluminum particles from environmental factors and prevents rapid oxidation. When aluminum with the oxide layer is placed in normal water, there could be limited reactivity between the aluminum and water due to the presence of the stable oxide layer. The aluminum oxide layer serves as a protective barrier that inhibits direct contact between the aluminum and water, reducing the likelihood of rapid chemical reaction. In most cases, the aluminum oxide layer would prevent significant interaction with water, maintaining the integrity of the aluminum particles.

Consequently, the ultrasound agitation technique can be used to remove the oxide layer on both silicon particles and aluminum particles.

Fig. 7 schematically illustrates a standalone device 11 for supplying electricity. The standalone device 11 may be configured as described with reference to any of the preceding figures, with the modification that the standalone device 11 differs from the previously described embodiments in that it does not include any auxiliary fuel cell, but only a main fuel cell 901, which is integrated with the device 11.

In this context, the term integrated may be understood as the main fuel cell 901 being mounted to the same frame as the reaction chamber 120 and the electrolysis device 400 (if any). In some embodiments, the electrolysis device 400 and the main fuel cell 901 may be mounted on the reaction chamber 120.

Such a standalone device 11 may be mounted to a mobile or portable platform 12.

A mobile platform may form part of any type of vehicle, in particular an automobile, a motorcycle, a boat, an aircraft, or the like and where a portable platform 12 may form part of a portable power generator or a range extender for an electric vehicle.

A mobile platform may comprise a vehicle frame, which may form part of a chassis, hull or body of the vehicle and which supports components of the vehicle, including the standalone device 11.

The standalone device 11 may comprise an additional TEG 905 which is thermally coupled to the main fuel cell 901, but otherwise provided as disclosed with reference to fig. 1.

The standalone device 11 may further comprise an electrolysis device 400, which is configured to use excess electricity to provide hydrogen gas and oxygen gas that can be stored and/or fed to the main fuel cell 901.

The standalone device 11 may further comprise a water recycling arrangement 113, as the one described above. The standalone device 11 may be embodied as a portable device, in particular a portable power supply unit, which can be used to provide electric power of a standardized voltage and duty cycle at sites which do not have access mains power supply and/or as a back-up power supply unit for use in case of power outage.

A portable device would comprise a device frame, which may support components of the device, such as power electronics for converting a direct current received from a fuel cell to an alternating current that may correspond to a mains current, as well as the standalone device 11. The device frame may also be connected to a handle and/or wheels for facilitating its portability.

The standalone device 11 may comprise an Automatic Transfer Switch (ATS), which is a device that automatically detects a power outage and switches the standalone device 11 on, ensuring seamless transition from utility power to backup power. This may be advantageous for ensuring continuous power supply without manual intervention.

The standalone device 11 may further comprise a carrying handle and/or a non-driven set of wheels by which the standalone device 11 may be moved by a user. Preferably, the standalone device should weigh less than 50 kg, preferably about 1-5 kg, about 5-10 kg, about 10-20 kg, about 20-30 kg, about 30-40 kg or about 40-50 kg.

The standalone device may have at least one electric output connector configured as a standardized mains outlet connector. Such standard connectors include, but are not limited to, the US standards Type A (NEMA 1-15 U.S. 2 pin) and Type B (NEMA 5-15 U.S. 3 pin), which provide 125 V AC up to 15 A, European standards, such as Type E (CEE 7/5), Type F (CEE 7/3) or type G (BS 1363).

The standalone device may further comprise a housing enclosing the system 11, wherein at least the electric output connector is accessible from outside the housing.

As another alternative, the standalone device 11, may be provided as a range extender assembly for an electric vehicle (including fully electric vehicles or plug-in hybrid electric vehicles).

An electric vehicle would typically comprise an electric power storage device, such as a battery, and an electric drive motor, connected to the electric power storage device, for propulsion of the vehicle, both of which would be directly or indirectly supported by the vehicle frame.

Fig. 8 schematically illustrates a cross sectional view of the reaction chamber 120 as seen from above. The reaction chamber 120 may be enclosed by a reactor wall 1201, which may have any form deemed suitable, but suitably a circular cross section.

A reactor wall 1201 may be formed from any suitable material, albeit preferably a material with good heat conduction properties, such as a metallic material and preferably a material which can withstand the chemical environment in the reaction chamber 120.

Such materials may be glass or stainless steel (in particular stainless steel grade 304, 316 and/or 317).

At least part of an inside surface 1206 of the reactor chamber 120 may be wholly or partially coated with a catalyst. For example the inside of the reactor wall may be coated by the catalyst.

A catalyst coating may be on the order of about a few microns up to a millimeter, preferably up to about 0.5 mm.

Determining the most effective catalyst for a specific reaction depends on various factors, including the reaction conditions, desired reaction rate, selectivity, and the specific objectives of the process.

Different catalysts may have different effects on the reaction kinetics and efficiency.

Platinum and nickel can be used as catalyst materials.

Alloys combining platinum with other metals from the platinum group (such as iridium, rhodium, palladium) is another option due to synergistic effects and improved performance.

High-entropy alloys, which consist of multiple principal elements in approximately equal proportions are yet another option.

Bimetallic catalysts composed of two different metals, such as nickel-copper, iron-palladium, or cobalt-rhodium are further options.

Alloys combining noble metals like platinum, palladium, or gold with nickel are yet further options.

Another option is to use a GaPt (gallium-platinum) alloy as a catalyst. While not traditional metal alloys, MOFs consist of metal ions linked by organic ligands and are also options.

The effectiveness of a catalyst is typically evaluated based on its catalytic activity, selectivity, stability, and cost. The choice of the most effective catalyst for a given reaction system involves a careful balance of these factors. Additionally, optimization and tuning of catalyst properties, such as particle size, morphology, and surface area, can further enhance the catalytic performance.

Additionally or alternatively, other surfaces that come into contact with the water and metal slurry may be coated with the catalyst, such as surfaces of an agitator.

Any such surface may be provided with flanges, pores, trenches or the like configured for increasing an exposed surface on which the catalyst may be provided.

As yet another alternative, a catalyst may be provided on one or more pellets introduced into the reaction chamber 120. Such pellets may be porous so as to increase the exposed surface on which the catalyst may be coated. The pellets may be sized such that they remain in the reaction chamber and do inadvertently not accompany residual solids that are extracted from the reaction chamber.

As mentioned above, the TEG 904 may be arranged to cover at least part of an outside of the reactor wall 1201, such that it is thermally coupled to the reaction chamber 120.

An outer shell 1202 may enclose at least part of the reaction chamber 120, such that thermal insulation may be provided and, optionally, the TEG 904 may be enclosed by such thermal insulation.

In a space S formed between the reactor wall 1201 and the outer shell 1202, there may be provided a cooling medium, which may be allowed to pass through the space to convey heat from the reaction chamber and to increase a thermal gradient over the TEG, if any.

The cooling medium may be a gas, such as air, or a liquid, such as water.

An actuator in the form of a fan or a pump 1205 may be used to cause the cooling medium to move in the space.

Alternatively, or as a supplement, the cooling medium may be caused to move by a thermal drive, with an input 1203 at a lower portion of the space and an outlet 1204 at an upper portion of the space. A thermal drive may be regulated by one or more valves (not shown), which may control the flow of the cooling medium.

One or more temperature sensors may be provided for measuring the temperature at one or more locations in the space, in the reaction chamber of at the reaction chamber wall, whereby the fan(s), pump(s) or valve(s) may be controlled based on data received from such temperature sensor(s).

Fig. 9a schematically illustrates an airlock 700 that can be provided for supplying materials, such as silicon and/or pH adjustment agent, to the reaction chamber 120.

The airlock 700 may comprise an airlock chamber 1023, a reaction chamber door 1021 and an outer door 1022.

In some embodiments, a feed mechanism 101 may be arranged inside the airlock chamber 1023. Hence, the outer door 1022 may be used for replenishing the feed mechanism. The feed mechanism 101 may then supply one or more materials to the reaction chamber 120 through the reaction chamber door 1021 so long as there is sufficient material in its magazine.

Alternatively, in some embodiments, the feed mechanism may be arranged on the outside of the airlock chamber 1023. Hence, the feed mechanism may feed to the airlock chamber 1023 through the outer door 1022, whereby the material supplied is fed to the reaction chamber 120 through the reaction chamber door

1021 once the outer door 1022 has been properly closed.

As shown in fig. 9a, the airlock 700 may be arranged on the outside of a wall enclosing the reaction chamber 120.

Opening and closing of the reaction chamber door 1021 and the outer door

1022 may be controllable by the controller 600.

The reaction chamber door 1021 and the outer door 1022 may be configured to provide airtight seals.

An air conditioning device may be provided may be provided for controlling the atmosphere in the airlock chamber 1023, for example by relieving a pressure differential and/or evacuating hazardous gas present in the airlock chamber to prepare, in particular, for opening of the outer door 1022.

Alternatively, as shown in fig. 9b, the airlock 700 may be arranged on the inside of a wall enclosing the reaction chamber 120. A single airlock 700 may be used for all materials that are to be supplied to the reaction chamber.

Alternatively, separate airlocks may be used for different materials.

Claims

1. A system for producing hydrogen gas by reacting silicon and water, comprising: a reaction chamber (120), a water supply arrangement (110), configured for supplying water to the reaction chamber (120), a silicon supply arrangement (100), configured for supplying silicon to the reaction chamber (120), a hydrogen collection arrangement, configured for collecting hydrogen gas from the reaction chamber (120) and supplying said hydrogen gas via a main output channel to an application hydrogen consumer, and a controller (600), configured to control at least one of the water supply arrangement (110), the silicon supply arrangement (100) and the hydrogen collection arrangement.

2. The system as claimed in claim 1, further comprising at least one hydrogen vent device, configured for ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and an auxiliary fuel cell (901), configured to receive and operate based on said ventilated hydrogen gas.

3. The system as claimed in claim 1 or 2, wherein the system further comprises an electrolysis device (400) for generating hydrogen gas and oxygen gas by electrolysis of water.

4. The system as claimed in claim 3, wherein the electrolysis device (400) is configured for feeding hydrogen gas to the auxiliary fuel cell (901) and/or to the application hydrogen consumer.

5. The system as claimed in claim 3 or 4, wherein the electrolysis device (400) is configured for feeding oxygen gas to the application hydrogen consumer.

6. The system as claimed in any one of the preceding claims, wherein the system further comprises an electric energy buffer (902, 903), such as a battery or a capacitor.

7. The system as claimed in any one of the preceding claims, wherein the system further comprises at least one agitation device (300) for agitating reagents in the reaction chamber (120).

8. The system as claimed in claim 7, wherein the agitation device (300) comprises a first ultrasonic actuator which is provided in a lowermost portion of the reaction chamber (120).

9. The system as claimed in claim 7 or 8, wherein the agitation device (300) comprises a rod extending upwardly from a bottom portion, in particular from a lowermost portion of the bottom portion, of the reaction chamber (120).

10. The system as claimed in claim 7 or 8, wherein the agitation device (300) comprises a plate forming at least part of a surface in the reaction chamber (120) for supporting wholly or partially reacted silicon.

11. The system as claimed in any one of claims 7-10, further comprising a mechanical agitator, configured to mechanically agitate, in particular stir, silicon and/or silicon oxide particles deposited on or near a bottom portion of the reaction chamber (120).

12. The system as claimed in any one of claims 7-11, further comprising at least one second ultrasonic actuator, which is spaced from a bottom of the reaction chamber (120), the second ultrasonic actuator comprising: at least one sonicator probe (801, 804), and a particle separator (802, 803), wherein the sonicator probe (801, 804) is configured to agitate particles present on the particle separator (802, 803), and wherein the particle separator (802, 803) is configured to allow particles smaller than a predetermined size to pass.

13. The system as claimed in claim 12, wherein the system comprises at least two said sonicator probes (801, 804), which are positioned at different distances from a bottom of the reaction chamber (120).

14. The system as claimed in claim 12 or 13, wherein the system comprises at least two said particle separators (802, 803), which are positioned at different distances from the bottom region of the reaction chamber (120).

15. The system as claimed in any one of the preceding claims, wherein a bottom portion of the reaction chamber (120) is inclined towards the lowermost portion of the reaction chamber (120).

16. The system as claimed in any one of the preceding claims, further comprising a thermoelectric generator, thermally coupled to the reaction chamber (120) so as to receive heat from the reaction chamber (120).

17. The system as claimed in claim 16, wherein the reaction chamber (120) presents a reaction chamber wall defining a reaction space and an outer wall, which encloses at least part of the reaction chamber wall, wherein the thermoelectric generator is thermally coupled to the reaction chamber (120) wall.

18. The system as claimed in claim 16 or 17, further comprising a cooling medium provided in a space formed between the reaction chamber (120) wall and the outer wall.

19. The system as claimed in claim 18, further comprising an actuator configured to drive the cooling medium through the space.

20. The system as claimed in any one of the preceding claims, further comprising: an application comprising at least one application hydrogen consumer, an electric energy buffer (902, 903), such as a battery or a capacitor, and a thermoelectric generator, thermally coupled to the application hydrogen consumer so as to receive heat from the application hydrogen consumer, the thermoelectric generator configured to supply electric energy to the electric energy buffer (902, 903) and/or to an electric energy buffer (902, 903) configured for powering the application.

21. The system as claimed in any one of the preceding claims, further comprising at least one component that generates residual water, and a water return device for returning said residual water to the water supply arrangement (110) or to the reaction chamber (120).

22. The system as claimed in claim 21, wherein the component that generates residual water comprises a condenser unit.

23. The system as claimed in claim 22, wherein the condenser unit is connected to receive water vapor from at least one of: a slurry dryer, an auxiliary fuel cell (901), and the application hydrogen consumer.

24. The system as claimed in any one of claims 21-23, wherein the component that generates residual water comprises a first separator unit (301) for separating solid material from a liquid.

25. The system as claimed in any one of claims 21-24, further comprising a second separator unit (302) for separating at least one solid material from at least one further solid material.

26. The system as claimed in any one of the preceding claims, further comprising a mechanical grinding device (102) configured for grinding the silicon into particles, wherein the grinding device (102) is arranged inside the reaction chamber (120) and configured to utilize the water as grinding liquid.

27. The system as claimed in claim 26, wherein the grinding device (102) is configured to grind the silicon into particles having a particle size less than about 500 pm, less than about 250 pm, less than about 100 pm, preferably less than about 50 pm, less than about 25 pm, less than about 10 pm, less than about 1 pm, less than about 500 nm, less than about 100 nm, less than about 50 nm, less than about 25 nm or less than about 10 nm.

28. The system as claimed in any one of the preceding claims, further comprising a catalyst, provided inside the reaction chamber (120).

29. The system as claimed in any one of the preceding claims, further comprising: a pH sensor configured to detect a pH in the reaction chamber (120) and to supply a corresponding signal to the controller (600), and a pH adjusting device, which is controllable by the controller (600) and configured to provide at least one non-toxic pH adjustment agent to the reaction chamber (120).

30. The system as claimed in any one of the preceding claims, further comprising an electrolysis device (400) configured to receive water from the water supply arrangement (110) and to supply hydrogen gas to the hydrogen collection arrangement (171).

31. The system as claimed in claim 30, further comprising an oxygen collection device, configured to receive oxygen gas from the electrolysis device (400) and for supplying the oxygen gas to the application hydrogen consumer and/or to the auxiliary fuel cell (901).

32. The system as claimed in any one of the preceding claims, further comprising: at least one hydrogen vent device, configured for ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and a channel connecting the hydrogen vent device to the application hydrogen consumer for feeding ventilated hydrogen to said application hydrogen consumer.

33. The system as claimed in claim 32, wherein the application hydrogen consumer is a fuel cell or an internal combustion engine.

34. The system as claimed in claim 32 or 33, further comprising a thermoelectric generator, thermally coupled to the application hydrogen consumer so as to receive heat from the application hydrogen consumer, the thermoelectric generator configured to supply electric energy to the electric energy buffer (902, 903) and/or to an electric energy buffer (902, 903) configured for powering the application.

35. The system as claimed in any one of the preceding claims, further comprising at least one airlock (700), wherein at least one of the silicon supply arrangement (100) and an additive is configured to feed to the reaction chamber through said airlock.

36. A system as claimed in any one of the preceding claims, wherein the system is mounted on a mobile or portable platform.

37. A vehicle, comprising: a vehicle frame, an electric power storage device, an electric drive motor, connected to the electric power storage device and configured to propel the vehicle, and a system as claimed in any one of the preceding claims, supported by the vehicle frame and configured to provide electric power to the electric power storage device and/or to the drive motor.

38. The vehicle as claimed in claim 37, wherein the vehicle is an automobile, a motorcycle, a moped, a boat, a fixed wing aircraft or a rotary wing aircraft.

39. A portable device, comprising: a device frame, an electric output connector, optionally an electric power storage device, configured to provide electric power to the electric output connector, and a system as claimed in any one of claims 1-36, supported by the device frame and configured to provide electric power to the electric output connector and/or to the an electric power storage device.

40. The portable device as claimed in claim 39, wherein the electric output connector is configured as a standardized mains outlet connector.

41. The portable device as claimed in claim 39 or 40, further comprising a housing enclosing the system, wherein the an electric output connector is accessible from outside the housing.

42. A method for producing hydrogen gas by reacting silicon and water, comprising: supplying water to a reaction chamber (120), supplying silicon to the reaction chamber (120), collecting hydrogen gas from the reaction chamber (120) and supplying said hydrogen gas via a main output channel to an application hydrogen consumer, and wherein a controller (600) is used control at least one of said supply of water, said supply of silicon and said collection of hydrogen gas.

43. The method as claimed in claim 41, further comprising: using at least one thermoelectric generator to generate electric power from thermal energy received from the reaction chamber (120), storing said electric power in an electric energy buffer (902, 903), and supplying said electric power to power at least one of the controller (600), the supply of water, the supply of silicon and the collection of hydrogen gas.

44. The method as claimed in claim 41 or 42, further comprising ventilating some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, collecting said ventilated hydrogen gas, feeding said ventilated hydrogen gas to an auxiliary fuel cell (901), and using the auxiliary fuel cell (901) generate electric power, storing said electric power in an electric energy buffer (902, 903), and supplying said electric power to power at least one of the controller (600), the supply of water, the supply of silicon and the collection of hydrogen gas.

45. The method as claimed in claim 42 or 44, further comprising: generating hydrogen gas and oxygen gas by electrolysis of water in an electrolysis device (400), wherein said electrolysis device (400) is powered by the electric power.

46. The method as claimed in claim 45, further comprising collecting oxygen gas from the electrolysis device (400) and supplying the oxygen gas to the application hydrogen consumer and/or to the auxiliary fuel cell (901), if any.

47. The method as claimed in any one of claims 41-45, further comprising using a thermoelectric generator, which is thermally coupled to an application hydrogen consumer, to generate electric power, storing said electric power in an electric energy buffer (902, 903), and supplying said electric power to power at least one of the controller (600), the supply of water, the supply of silicon and the collection of hydrogen gas.

48. The method as claimed in any one of claims 41-46, further comprising agitating the water and silicon present in the reaction chamber (120) using at least one agitation device (300).

49. The method as claimed in claim 48, comprising using at least one first ultrasonic actuator to agitate silicon in a bottom region of the reaction chamber (120).

50. The method as claimed in claim 48 or 49, comprising using at least one second ultrasonic actuator (801, 804) to agitate silicon in a region spaced from the bottom region of the reaction chamber (120).

51. The method as claimed in claim 50, further comprising selectively retaining silicon in the region spaced from the bottom region of the reaction chamber (120) while agitated by the second ultrasonic actuator.

52. The method as claimed in any one of claims 48-51, further comprising: detecting an indication of a hydrogen production rate in the reaction chamber (120), and varying operation of at least one of the first ultrasonic actuator and the second ultrasonic actuator in response to said indication.

53. The method as claimed in any one of claims 48-52, comprising: supplying the silicon to the reaction chamber (120) having a first particle size, and using the agitation device(s) (300) to reduce the first particle size to a second, smaller particle size.

54. The method as claimed in any one of claims 42-53, comprising: providing the silicon having a particle size of about 0.1-5 mm, preferably about 0.1-2 mm or about 0.1-1 mm, mechanically reducing particle size of the silicon into smaller silicon particles, wherein said mechanically reducing particle size is performed inside the reaction chamber (120) with water present in the reaction chamber (120) as grinding liquid, and collecting hydrogen gas formed during said grinding.

55. The method as claimed in claim 53 or 54, wherein said silicon particles are reduced into silicon particles having a particle size less than about 500 pm, less than about 250 pm, less than about 100 pm, preferably less than about 50 pm, less than about 25 pm, less than about 10 pm, less than about 1 pm, less than about 500 nm, less than about 100 nm, less than about 50 nm, less than about 25 nm or less than about 10 nm.

56. The method as claimed in any one of claims 42-55, further comprising generating residual water and returning at least some of said residual water to the reaction chamber (120).

57. The method as claimed in claim 56, wherein said generating residual water comprises condensing water vapor.

58. The method as claimed in claim 56 or 57, wherein said generating residual water comprises separating a solid material from a liquid.

59. The method as claimed in any one of claims 42-58, further comprising separating at least one solid material from at least one further solid material.

60. The method as claimed in any one of claims 42-59, further comprising sensing a pH value in the reaction chamber (120) and supplying at least one, preferably non-toxic, pH adjusting agent to the reaction chamber (120).

61. The method as claimed in claim 60, wherein the pH adjusting agent is provided in a capsule, which is opened or dissolved to release the pH adjusting agent.

62. The method as claimed in claim 61, wherein the capsule is provided by a feed mechanism, such as a feed magazine or a feed web.

63. The method as claimed in any one of claims 42-60, further comprising: ventilating at least some of the hydrogen gas in order to reduce or prevent excess hydrogen pressure, and feeding ventilated hydrogen to said application hydrogen consumer.

64. The method as claimed any one of claims 42-61, further comprising: using at least one electric energy generating component to generate electric power from thermal energy received from the application hydrogen consumer, storing said electric power in an electric energy buffer (902, 903), and supplying said electric power to power at least one of the controller (600), the supply of water, the supply of silicon, the collection of hydrogen gas and the application hydrogen consumer.

65. The method as claimed in any one of claims 42-62, comprising: providing the silicon as powder in an enclosed capsule, which is formed from a metallic material, in particular aluminum, opening the capsule, feeding the metal powder from the capsule to the water, mechanically converting the capsule into metallic capsule powder, and allowing the metallic capsule powder to react with the water to form hydrogen gas.

66. The method as claimed in any one of claims 42-63, wherein the silicon comprises scrap silicon from used semiconductor devices.

67. The method as claimed in any one of the preceding claims, further comprising providing at least one catalyst in the reaction chamber (120).

68. A method of providing power to a mobile or portable platform, comprising the method as claimed in any one of claims 42-65.

69. The method as claimed in any one of the preceding claims, wherein at least one of the silicon and the pH adjustment agent is fed to the reaction chamber through an airlock.