Economic feasibility assessment of calcium looping energy storage and carbon capture with multi-market modelling approach

Long-duration energy storage is essential for renewable energy systems due to increasing variability in power grids. This study evaluates the techno-economic feasibility of a potential technology, calcium looping thermochemical energy storage (CaL TCES), within the Finnish electricity market, employing the multi-market modelling tool Predicer. The objective of the study is to improve economic feasibility assessment of CaL TCES by optimizing the system's participation in multiple electricity markets. A case study is explored where CaL TCES is integrated into a biomass combined heat and power (CHP) plant for both energy storage and carbon capture. Results show that participation in both spot day-ahead and manual frequency restoration reserve (mFRR) markets increases operational hours, and revenue compared to spot market participation alone, with electricity market revenue increasing 56% and 79% in 2023 and 2024, respectively. Despite this, the net present value (NPV) remains negative. The break-even selling price of electricity (BESP) was 463 €/MWh, with an NPV of −115 M€. Investment costs dominate lifetime costs, even with potential reductions through industrial integration. Revenues from CO₂ utilization and district heat exceed those from the electricity market, highlighting that electricity market revenues alone are insufficient for economic viability. Sensitivity analyses suggest that profitability could be achieved with simultaneous changes in several economic components: 30% decrease in CAPEX and OPEX, increases in electricity market and district heating revenues, a lower electricity tax and discount rate. In conclusion, while CaL TCES has potential for retrofit applications, significant cost reductions are necessary for profitability in renewable energy-based systems like Finland's.