Design and performance simulation of coupled electrolyzer-metal hydride hydrogen compressor system as a part of hydrogen refueling station

Metal hydrides have shown to play an important role in the “hydrogen economy” infrastructure for various applications including hydrogen/thermal energy storage systems, hydrogen compression, etc. The deployment of hydrogen-powered electric vehicles is hampered by many challenges including on-board hydrogen storage and hydrogen refueling. As an example, hydrogen refueling stations (HRS) stand as the most complex system in the hydrogen infrastructure pathway. An HRS comprises of two main components: a hydrogen production and a hydrogen compression device to provide hydrogen to end-users at high pressure. Although there are many hydrogen production methods, hydrogen production via water electrolysis is the most promising option. However, water electrolysis becomes cost-effective only if high-grade energy (electricity) is provided by an excess, renewable and free source (Solar PV, wind turbine). On the other side, the hydrogen compression is also a conundrum in HRS design and implementation. The use of available mechanical compressors makes the HRS cost-prohibitive since they account for more than 40 % of the total installed cost. To alleviate this hurdle, an interest to thermally driven metal hydride hydrogen compression (MHHC) has dramatically risen. This was due to simplicity in design and operation, safety and reliability, and a possibility to use low to medium-grade waste heat, instead of electricity, for hydrogen compression.