Boundary Technology Costs for Economic Viability of Long-Duration Energy Storage Systems in California

The urgent need for decarbonization in the energy sector has led to an increased emphasis on the integration of renewable energy sources, such as wind and solar, into power grids. While these resources offer significant environmental benefits, they also introduce challenges related to intermittency and variability. Long-duration energy storage (LDES) technologies have emerged as a very promising solution to address these challenges by storing excess energy during periods of high generation and delivering it when demand is high or renewable resources are scarce for a sustained amount of time. This paper introduces a novel methodology for estimating the boundary technology cost of LDES systems for economic viability in decarbonized energy systems. Our methodology is applied to estimate the boundary costs in 2050 for the state of California to achieve full retirement of gas power plants. California's ambitious decarbonization goals and transition to a renewable energy-based power system present an ideal context for examining the role of LDES. The results also offer insights into the needed capacity expansion planning and the operational contribution of LDES in the California's energy landscape, taking into account the unique energy demand profiles and renewable resource availability of the region. Our findings are intended to provide complementary information to guide decision-makers, energy planners, and any other stakeholders in making informed choices about LDES investment in the context of a decarbonized energy future.