Large scale low‐cost green hydrogen production using thermal energy storage and polymer electrolyte membrane electrolysis systems

Abstract

With increased dominance of renewable energy in developed countries, there is increased frequency of excess electricity and grid inflexibility. Without sufficient energy storage, renewable assets become stranded. With aims for net-zero carbon emissions, countries are looking to green hydrogen to replace fossil fuels. A combined system of affordable large scale energy storage and electrolysis is proposed to address these issues. An original approach, using low-cost wholesale grid electricity and thermal energy storage for proton exchange membrane electrolysis, has been modelled. An electricity price control mechanism is used for the operation of an electric thermal energy storage system. A 1600 MW grid connection provides power for resistance heating to charge 45 GWh capacity thermal energy storage, which powers a 20 MW rated steam turbine. This then powers a 17.5 MW electrolyser, and compression system during high-cost electricity periods. Grid power charges the storage and powers electrolysis during low-cost periods. Model simulation data allows the calculation of combined system lifecycle costs and levelized cost of hydrogen, which lead to profitability analyses. Results of system simulations give hydrogen costs lower than those of current and projected green hydrogen production methods. Simulation provides evidence that an initial investment of 64.4 million US dollars, could yield 1.14$/kg of hydrogen, 5.2 tonnes/day of hydrogen, and a 230% return on investment capital, through use of excess renewable energy.