Quantitative assessment of the economic feasibility of thermal storage systems

Abstract

As concerns over climate change grow and large-scale introduction of variable renewable energy is expected in many countries, the importance of energy storage systems is more strongly recognized than ever before. While batteries have been one of the most widely preferred storage methods, the use of thermal storage technology is also beginning to attract attention. Thermal storage has a lower installation cost than electricity storage, but its cycle efficiency is poor, so it is expected that the two options will be used complementarily in energy systems. In this study, we used a technology selection model based on linear programming to quantitatively evaluate the economic value of thermal storage in a situation in which Japan aims to achieve zero energy-related CO₂ emissions by 2050. As a result, it was shown that if the cost of thermal storage exceeds 10,000 yen/kWh in 2050, compared to the assumed cost of lithium-ion batteries of 15,000 yen/kWh, its feasibility is lost, but if the cost falls below 5,000 yen/kWh, a large amount of thermal storage systems will be introduced in the optimal solution. It was also shown that cycle efficiency largely influences the value of thermal storage systems. These results suggest that with continued technological development to improve costs and cycle efficiency, thermal storage technology can make a significant contribution to stable supply in future power systems.