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COmbined hybrid Solution of Multiple HYdrogen Compressors for decentralised energy storage and refuelling stations

Periodic Reporting for period 3 - COSMHYC (COmbined hybrid Solution of Multiple HYdrogen Compressors for decentralised energy storage and refuelling stations)

Reporting period: 2020-10-01 to 2021-02-28

Ease of use and speed of refuelling are essential for the success of Hydrogen mobility. Fuel Cell Electric Vehicle (FCEVs) are fuelled with gaseous hydrogen at pressures of 350 or 700 bar and H2 compression is a key component of refuelling. Costs and efficiency of compression are crucial and COSMHYC tackled this challenge with a new compression solution for hydrogen refuelling stations. The technology can also be used for refilling of compressed hydrogen trailers.
This COSMHYC solution combines an innovative metal hydride compressor (MHC) with a mechanical compressor (MC). The MHC is based on a thermo-chemical effect: hydrides absorb low pressure hydrogen at low temperature and release high-pressure hydrogen at high temperatures, enabling to reduce maintenance costs and noise disturbance, and to replace the use of electricity with waste heat. One main result of the project is the use of metal hydrides without rare earths in a TRL6 prototype. The MC diaphragm technology was improved beyond state-of the art, with 5% efficiency improvement, reduction of noise level, improvement of life time and significant cost reductions.
The joint tests of the 2 technologies demonstrated the feasibility to combine them for compressing 4 kg/h in a baseload with the MHC, corresponding to 100 kg/day, and to distribute them at a very high speed of 60 kg/h with the MC. The pressure levels of respectively 450 bar and 950 bar for the MHC and MC were demonstrated, enabling all considered applications (FCEV refuelling at 700 bar, bus and train refuelling at 350 bar, and compressed gaseous H2-trailer filling at 300 bar). Further optimisation potential has been identified, especially on the BoP of the MHC, its thermal insulation and fine-tuning of hydrides composition to optimise capacity. More developments will be needed for increasing the capacity for large scale applications and to demonstrate it in real life. Yet, the potential to lower investment and operational costs and to increase the availability of stations has been confirmed. Also, the solution enables significant noise reduction. At mass production, the hybrid COSMHYC solution is expected to lead to a reduction by 20% of the hydrogen costs at the refuelling station.
The first phase of the project, mainly focused of design, development and test of materials and sub-systems:
• Appropriate hydrides were identified and produced for compression from 5 to 450 bar, ensuring the core performance of the MHC while using rare earth free metal alloys. Reactors were designed and tested for increasing performances (mechanical resistance, reaction kinetics, flow rates and compression ratios) allowing to demonstrate compression ratios of 10 to 35 at lab scale. All reactors were submitted to a comprehensive certification process. The MHC prototype was then carefully designed, with focus on heat and control systems.
• On the MC, key developments included optimization of component designs, internal cooling to reduce wear, improved materials and surfaces of the diaphragm to increase lifetime. All improvements were integrated in a prototype for laboratory, including new low-noise hydraulic relief valves and new balance-of-plant components.
The second phase of the project focused on assembly and tests of both prototypes which were tested under joint protocols to investigate their combined operation in the COSMHYC hybrid configuration.
- More than 4000h of tests were performed on the MC prototype demonstrating a capacity of more than 60 kg/h. Endurance tests demonstrated 10th of millions of cycles, with over 5000 start and stops. Pressure range of the MC is well in phase with the capacity of the MHC, allowing the combination of both compressors.
- The MHC reached the expected pressures stages. The partners were able to overcome technical issues related to BOPs, building know-how for further steps towards industrialisation. The prototype can work under the combined configuration as well as a standalone solution, meeting the requirements of end-users. The observed peak flow rate is up to 7 kg/h and the flow rate over 1 hour 2,2 kg/h. Long-term average flow rate range from a few 100s g/h to a few kg/h. These values are far higher that the state of the art of MHC.
The technologies reached very promising performances and the pertinence of combining both technologies was demonstrated. Results were presented during a final online dissemination event, with large attendance of industry experts, potential customers & end-users. A roadmap towards exploitation was established, focusing on commercial exploitation. The consortium also actively worked on next development steps with follow-up projects COSMHYC XL (developing the concept further for large scale applications) and COSMHYC DEMO (demonstration within an HRS operating in real life conditions). Finally, a start-up was created for commercial exploitation of the MHC.
For the metal hydride technology, the selection of metal hydrides without rare earth but with appropriate performances is a significant step beyond the state of the art (existing MHC prototypes are most of time using rare earths, showing poor heat transfer capacity, limited flow rate or high energy consumption). The new hydrides, are adapted for reaching the targets of the COSMHYC project. The innovative design of the reactors enables to scale up the technology by a factor 10 compared to the state-of-art of MHC.
The MHC prototype is a stand-alone product, including all required BoP (cooling, monitoring, safety), an autonomous controller (PLC & HMI) as well as containerised design, which makes it adapted to an outdoor exploitation under representative operation conditions. Therefore, a maturity level corresponding to TRL5 was reached, which is a significant step beyond the state-of-art towards industrialisation and commercialisation.
Also, the advances on the MC in performances (operational temperature range, endurance, energy consumption) are far beyond existing MC and compatible with a wide deployment of hydrogen mobility.
The achievements in terms of noise reduction can be highlighted: the MHC demonstrated a noise disturbance of only 53.9 dB in day mode and 50.6 dB in night mode. The MC demonstrated a noise level < 60DB can be reached. These achievements are far better than the state-of-art of mechanical compressors (85 DB).
The pertinence of the combination of both compression technologies was demonstrated thanks to the long-term tests, enabling to validate the possible synergies between both technologies for achieving various compression levels and a high level of flexibility. This modular scalability is an innovative feature of the COSMHYC solution. This hybrid approach enables to reach peak flow rates of up to 60 kg/h, compatible with the requirement of typical hydrogen refuelling stations. This will have a significant impact on the future costs of refuelling stations.
A techno-economic analysis showed that the COSMHYC solution has cost advantages over benchmark technology. Further costs reductions are possible related to system simplifications and mass production. Specific CAPEX of <1450 €/(kg*day) for the MHC and 105 €/(kg*day) for the MC booster were demonstrated, resulting in an overall 1550 €/(kg*day), significantly better than the expected project KPI (2000 €/(kg*day)), proving the high potential of the COSMHYC solution.
Metal hydride power used in the reactors of metal hydride compressor
Principle of the COSMHYC compression concept
Crank case of the mechanical compressor
Metal alloy Ingot for metal hydride powder production
Metal Hydride Compressor within its container at the long term test site