Feasibility of Supercritical CO2 Energy Storage in Finnish Energy System

Abstract

The increasing share of variable renewable energy sources creates a need for energy storage technologies capable of providing medium-to-long storage duration. Supercritical CO2 energy storage is a promising option due to its high energy density and potential for comparably high round-trip efficiency, but its economic performance under real market conditions remains uncertain. This study presents a dynamic model of a supercritical CO2 energy storage system and evaluates its operation in the Finnish day-ahead electricity market using historical hourly prices from 2018, 2020, 2022, and 2024. Storage operation is controlled using charging and discharging price thresholds defined as yearly price percentiles. The results show that profitability from energy arbitrage alone is limited, with annual profits remaining modest even during periods of high price volatility. The findings indicate that increasing volatility improves economic performance, but additional revenue streams are required to achieve long-term economic viability of the proposed storage system.