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

Abstract

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.