Abstract.

Electricity grid operation requires balancing supply and demand for electricity on a continuous basis. The primary option for dealing with the variability in renewable energy generation is to maintain a significant capacity of backup/standby ‘peaker’ generation. Still, off-peak renewable electric production is sometimes curtailed because it cannot be economically used or captured. Low cost, efficient energy storage could enable optimized allocation of intermittent electric generation resources to high-value markets. This research project investigates the feasibility and energy system costs and benefits of hydrogen energy storage (HES) integrated with the electricity grid. This analysis aims to illuminate the impacts of responsive water electrolysis in high-renewable penetration electricity grids to convert renewable electricity into low-carbon hydrogen. This process has the potential to help balance the electric grid while providing an energy carrier that could be used in diverse energy applications.

This research found that round-trip energy arbitrage via H2 as a storage medium, given a surplus of intermittent renewable generation, is not cost effective. Low round trip efficiencies and high capital cost makes it suboptimal to invest in hydrogen generation infrastructure for arbitrage alone. The sale of H2 as a transportation fuel has the potential to be a high value stream for otherwise excess generation capacity. Optimal investment in electrolysis and H2 storage capacity allows for this value to be captured, given an exogenous market for H2 fuel. Through the utilization of an H2 generation system, highly renewable systems can: reduce the cost to operate the grid, increase renewable integration into the energy supply, and provide enough hydrogen to fuel millions of fuel cell electric vehicles (FCEVs) at costs that are competitive with gasoline on a cent per mile basis.