HYDROGEN STORAGE: THE ROLE OF THE OF THE SUBSURFACE IN A HYDROGEN ECONOMY

Hydrogen (H­₂) is a versatile energy carrier that can be used to decarbonize high-emitting industrial processes (e.g., cement and steel making) and the power sector if deployed in conjunction with renewables. Large-scale storage is one of the major challenges that must be overcome to increase the use of H₂ in the energy economy. Underground H₂ storage (UHS) is an intriguing storage option that could be used to smooth variations in energy supply and demand and act as a capacitor between low-carbon energy generation and demand. Existing natural gas storage facilities in the United States (U.S.) are a logical first place to estimate hydrogen storage volumes because the subsurface geology has already proven favorable for gas storage. In this work, we provide an overview on why subsurface hydrogen storage is needed and discuss the potential for subsurface storage of pure (i.e., 100%) H₂ and blended mixtures of H₂ and natural gas (NG) in existing natural gas storage facilities across the conterminous United States (U.S.). The working-gas, H₂-energy content for storing pure H₂ in existing UGS reservoirs in the U.S. is estimated to be 327 terawatt-hour (TWh), while the total U.S. demand for clean H₂ is projected to grow to 3740 TWh per year. Meeting this demand could require a tenfold increase in UHS capacity, compared to what is potentially available in existing UGS reservoirs.