Techno-Economic Analysis of Long-Duration Energy Storage and Flexible Power Generation Technologies to Support High Variable Renewable Energy Grids

Variable renewable energy penetration is rapidly increasing around the world. As penetration increases beyond 80%, clean power systems will require long-duration energy storage or flexible, low-emission generation. These renewable firming technologies have not been evaluated simultaneously using both current and future costs in the context of uncertainty. Here, we provide a detailed techno-economic evaluation and uncertainty analysis of applicable technologies and identify key technology cost drivers and opportunities to support electric grid planning. We show that for 120-hour storage duration, hydrogen systems with geologic storage and natural gas with carbon capture achieve the lowest cost with both current and future capital costs. Finally, we also present a new storage system using heavy-duty vehicle fuel cells that could reduce costs by 22-27% compared to the best previously considered storage technology and thus may help enable very high (>80%) renewable energy grids.