Assessment of flexible coal power and battery energy storage system in supporting renewable energy

The use of renewable energy sources (RES) is expected to increase, potentially leading to volatility in the power system. Therefore, flexible power is essential to address this challenge. In China, two viable options for providing flexible power are battery energy storage systems (BESS) and flexibility modification of coal power units. This study introduces a framework to evaluate the costs of power system flexibility under varying RES shares on an hourly basis, comparing flexible coal power and BESS across several scenarios. In the short term, flexible coal power proves to be more advantageous than BESS, but BESS shows greater promise in the long run. The study suggests that while coal power will continue to play a critical role in the near future, it should gradually be phased out by reducing its utilization hours. Meanwhile, BESS should receive greater focus for long-term energy strategy. This study underscores the importance of maintaining power system stability throughout the low- carbon transition and highlights the need to balance short-term and long-term strategies for flexible power.