What would a US green hydrogen energy economy look like?

Abstract

Abstract Detailed description is given for a hypothetical US hydrogen economy with solar and wind energy supplying virtually all current energy needs and with electrolytic hydrogen the energy carrier and storage medium. Fossil fuels provide nonfuel products (plastics, chemicals, cement and asphalt). Only current technologies are considered and hydrogen storage accommodates generation intermittency and variability, using pit storage of high-pressure vessels in open air, yielding daily storage round-trip energy installation costs of 722 and 538 $/kWh for electric and thermal, respectively; and for power, 2351 and 2240 $/kW for electric and thermal, respectively. For long-duration storage, the costs are 94.1 and 23.8 $/kWh and 937 and 845 $/kW, respectively. Increased energy generation 20% over baseline accommodates low-season generation, obviates much required storage and ensures that reserves are topped off; 96% of US 2022 total energy consumption is provided for. In the default scenario (demand energy portions: half photovoltaic, quarter onshore wind and quarter offshore wind), the surface area for the farms (including offshore surface) requires ~4.6% of the US 48-state land area. About 350 pit storage sites provide both daily and long-duration storage, with the latter accounting for complete loss of generation for 4 days over a quarter of the nation. Hydrogen pipelines and a renewed electric grid transmit and distribute energy. The installation cost of the public infrastructure is ~$27.8 trillion for the default scenario. Alternative scenarios show significant infrastructure and cost savings when batteries are used for transportation and/or utility storage, provided current insufficiencies can be overcome. Broadly, cost levels in money, surface and infrastructure are within existing levels already achieved in historical events and modern living.