The role of long duration energy storage in decarbonizing power systems

Abstract

Plans for a decarbonized power system call for a significant increase in generation from variable renewable energy (VRE) sources, i.e. wind and solar. Yet, the intermittency of these resources introduces new challenges in operating the grid, including the need for sufficient operating flexibility to manage variations in VRE generation and load, while minimizing emissions and cost impacts. Long duration energy storage (LDES) has been suggested as an enabling technology for realizing high VRE penetrations in future grids because of its potential to flexibly time-shift VRE generation to match demand. However, the current literature lacks a broad assessment of the cost and performance requirements necessary for LDES technology to enable low- or zero-carbon power systems, the effect of various policy environments on those requirements, and an evaluation of currently existing LDES technologies and their potential to achieve sufficient cost and performance goals.

This work seeks to fill that gap. Using a power system capacity planning model with hourly dispatch and operating constraints for a full year in ²045, multiple scenarios are analyzed with differing climate policies, starting with a no policy base scenario and including region-wide carbon taxes, renewable energy requirements to target wind and solar generation, and clean energy standards to target zero- or low-emitting technologies. Currently existing LDES technologies, like power-to-gas, thermal energy storage, flow batteries, and others, are also evaluated and their potential future cost and performance are compared to the model results to identify which LDES technologies are likely to be viable contributors to decarbonizing the electricity sector. As a result, this research identifies key characteristics for LDES technology development and reinforces the role of policy in achieving decarbonized electricity systems.

Other findings include an evaluation of the role that existing LDES technologies may play in future decarbonized systems and the generation mix tradeoffs between LDES, lithium-ion batteries, and firm generation resources.