Optimal design of fully renewable and dispatchable power plants with hydrogen seasonal storage

The objective of this work is to assess the cost of electricity and the optimal design of fully-renewable energy systems using green hydrogen as seasonal energy storage. The study considers measured hourly data of the electricity demand in Sicily (Italy), as well as the electricity generation from photovoltaic plants and wind turbines. The cost optimal design of the aggregated energy system is performed by formulating and solving a mixed integer linear programming model including design and operational variables. Results show that the configuration with the hybrid storage (hydrogen + batteries) solution achieves the lowest cost of electricity. However, the economic advantage compared to the design case with batteries depends mainly on the H2 storage cost. If H2 is stored in pressurized tanks, the cost saving compared to the use of batteries is limited (215 €/MWh vs. 213 €/MWh in the current scenario, 123 €/MWh vs. 128 €/MWh with 2050 projections). The cost saving becomes considerable if a more economic geological H2 storage system is available: 192 €/MWh vs. 213 €/MWh in the current scenario, 97 €/MWh vs. 128 €/MWh for the 2050 scenario.