Addressing the low-carbon million-gigawatt-hour energy storage challenge

Replacing fossil fuels is difficult because they serve two functions: (1) energy and (2) energy storage to enable energy to be provided to the customer when needed. Fossil fuels have very low storage costs; thus, it may be harder to replace the storage function than the energy function of fossil fuels. To meet the variable hourly to seasonal demand for energy today in the United States, we store a 90-day supply of oil, a 30-day supply of natural gas and a 100+ day supply of coal. We require several million gigawatt-hours of energy storage for our economy to function. That energy storage capacity was built based on real-world experience over a century, not models. Our recent studies  (https://doi.org/10.1016/j.tej.2021.107042) indicate that there are only four affordable options for energy storage at this scale: nuclear fuel, liquid biofuels, hydrogen and heat. Options such as batteries may be used for short-term storage but are unaffordable for longer-term storage because of capital costs.