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An innovative approach for renewable energy storage by a combination of hydrogen carriers and heat storage

Periodic Reporting for period 3 - HyCARE (An innovative approach for renewable energy storage by a combination of hydrogen carriers and heat storage)

Reporting period: 2022-01-01 to 2023-07-31

Hydrogen tanks are required to store hydrogen after its production (i.e. electrolyzer) and before its utilisation (e.g. fuel cell or compression). One of the options to decrease cost of hydrogen storage significantly and to maximize the safety of the storage is to use metal hydride hydrogen storage systems, which can be easily integrated in existing and commercial hydrogen facilities. The use of metal hydrides allows a high storage capacity at much lower storage pressures (reducing safety distances) compared to the usual high-pressure storages required to achieve equivalent energy densities (i.e. MH allow smaller foot print for equivalent hydrogen stored mass). The main advantages in using hydrogen carriers based in metal hydride are the following: (i) large quantities of hydrogen stored in small volume (i.e. low footprint); (ii) improved energy efficiency of the whole process and (iii) higher safety of the storage.

The main objective of the HyCARE project was the development of a prototype hydrogen storage tank with use of a solid-state hydrogen carrier on large scale. The tank is based on an innovative concept, joining hydrogen and heat storage, in order to improve energy efficiency of the whole system. The energy produced by a renewable source (e.g. sun and wind) is used to produce H2 from water through an electrolyser. The gas is then stored in the designed tank using a carrier. A heat storage system collect the heat produced by the renewable plant, the electrolyser and from the MH, during H2 absorption. The collected heat is necessary during the desorption event to release hydrogen from the MH. Finally, the released H2 is used to supply a fuel cell (FC) producing electricity. The developed tank has been installed in the site of ENGIE LAB CRIGEN, located in the Paris Region (F). The developed tank was joined with a PEM electrolyzer as hydrogen provider and a PEM fuel cell as hydrogen user.

The main results obtained by HyCARE project are:
Couple hydrogen storage with thermal energy storage, providing improved energy efficiency
Store high quantity of stored hydrogen up to 46 kg
Integrate the prototype system with a real application (PEM electrolyser and a PEM fuel cell)
Improve safety of hydrogen storage: low pressure (< 50 bar), low temperature (< 100 °C) and production and handling of metal hydride material in air, without protective atmosphere
No hydrogen compression steps necessary
Innovative design, reducing the foot print of the storage system
Store and deliver hydrogen at high purity (> 99.99%)
The HyCARE consortium started to project activities since January 2019 and finished at the end of July 2023. Because of Covid pandemic, various delays have been encountered and the total duration of the project was higher than planned. An exhibition event entitled “The HyCARE system. Opportunities and challenges of the energy storage sector” was held in Paris on April 21st, 2023. The event showed the main results of activities carried out during the HyCARE Project.

Up to 46 kilograms of hydrogen are stored at less than 50 barg and less than 100 °C in a twenty-foot container. The innovative design is based on a maritime container, including twelve TiFe metal hydride hydrogen storage tanks, coupled with a thermal energy storage in PCM. The HyCARE hydrogen-heat-storage system consists of a complex construction, composed of several units/modules linked together and connected with different loops, which manage different fluids. Fluids involved in the system are the following: (i) hydrogen gas, (ii) cooling/heating water-glycol solution, (iii) nitrogen for instrumentation valve operation and (iv) argon for inertization of the HyCARE hydrogen-carrying equipment.
The system implements the recovery of the heat released during the hydrogen absorption in the hydride by storing it in the PCM, which is placed in 12 fixed tanks on the lower part of the container, each connected to one MH tank. This heat transfer between MH tanks and the PCM is performed via the cooling/heating fluid (or Thermal Fluid Vector – TFV, non-flammable non-toxic water-ethylene glycol mixture); this energy is later used during the desorption phase. The losses of energy through the insulation is supplied by an external source (solar panels where possible). The amount of heat to be stored in the PCM tank is correlated to the amount of hydrogen stored in the HyCARE system and correspondingly, to the reversible storage capacity of the metal hydride.
The HyCARE project made possible to develop a hydrogen storage tank with the use of a solid-state hydrogen carriers in large scale. The following KPIs beyond the SoA have been obtained:
Hydrogen Carrier: TiFe0.85Mn0.05
Volumetric capacity of H2 carrier: 69.3 kgH2/m3
Gravimetric capacity of H2 carrier: 1.1 wt%
Volumetric capacity (incl. tank): 1.36 kg H2/m3
Gravimetric capacity (incl. tank): 0.25 wt%
Nominal hydrogenation rate: 0.9 kgH2/(h kg)
Nominal dehydrogenation rate: 0.85 kgH2/(h kg)
Cooling/Heating demand: 2.8 kWh/kgH2
H2 pressure at inlet: 25 bar
H2 pressure at outlet: 1.5 bar
Footprint: 15 m2
Hydrogen storage capacity: 46 kg
Total roundtrip efficiency: 91.5 %
Number of cycles: 250 for carrier, 25 for system
H2 handled: 46 kg
CAPEX: 550000 EUR
OPEX: 100000 EUR/(kg/d)/yr

The project evaluated the impacts on the environment generated by the life cycle (production, use, disposal) of a storage system for hydrogen. The analysis of the environmental impacts was conducted by using the life cycle assessment methodology (LCA) and eight impact categories have been evaluated. Different scenarios have been assessed to properly evaluate the use phase and different storage solutions. In general terms to store the same amount of hydrogen the best solution is represented by using the HyCARE system that does not require the alloy replacement and uses heat for the management of thermal transfer, however, also the use of a system made of stainless steel tubes shows good environmental performances.

A technical-economic analysis (TEA) of liquid, gaseous and solid storage technologies for the storage of 40 kg H2 has been performed. The HyCARE system has a clear advantage in terms of availability, introducing large thermal inertia on the system (PCM) with a high heat exchange capability, guaranteeing temperature stability even for long standby periods, and heat source and sink for rapid desorption or absorption processes (so reducing auxiliars).

The Consortium Partners have agreed to sign a joint ownership agreement drafted by the Project Coordinator. The document lays the basis for future collaborations and further use of the HyCARE system. It was very useful the support of external consultants (HRB service) to address one or more specific aspects for the implementation of the business plan such as commercialisation plan, evaluation of business plan potential, creation of start-up, and access to non-EU funding through the analysis of funding options for follow-on financing. Further supports will be considered by the consortium.
HyCARE workshop
HyCARE exhibition
HyCARE concept
HyCARE system