Technoeconomic Insights into Metal Hydrides for Stationary Hydrogen Storage

Metal hydrides (MHs) are promising candidates for hydrogen storage due to their high volumetric energy densities and safety features. Recent developments suggest hydride systems can cycle and operate at pressures and temperatures favorable coupling with fuel cells for stationary long-duration energy storage applications. In this study, we present a conceptual design of a metal hydride-based storage system for backup power (0 to 20 MW supplied over 0 to 100 hours), and benchmark system cost and performance. Leveraging experimental hydrogen absorption and desorption data, we determine the uptake/release of hydrogen across likely pressure and temperature conditions, and estimate the equipment power, upfront capital cost, levelized cost of storage, land footprint, and energy density for a select number of metal hydrides and hypothetical operation scenarios. Our findings indicate that hydride-based storage systems hold significant size advantage in physical footprint, requiring up to 65% less land than the 170-bar compressed gas storage options. Metal hydride systems can be cost competitive with 350-bar compressed gas systems, with TiFe0.85Mn0.05 achieving $0.453/kWh and complex MH 2Mg(NH2)2-2.1LiH-0.1KH achieving $0.383/kWh, compared to $0.397/kWh for 350 bar compressed gas in the base case scenario. However, these advantages are sensitive to charging and discharging rate requirements, operational cycles and material manufacturing prices. Extending charging times and increasing operating cycles significantly reduce LCOS, especially for complex MHs, making them more competitive for applications with slow charging and long duration energy storage needs. Key strategies to further enhance the competitiveness of MHs include leveraging waste heat from fuel cells, increasing hydrogen uptake, and achieving metal hydride production costs of US$10/kg.