Back side of the coin: How does non-fossil energy diffusion result in less efficient fossil-based technologies

Non-fossil energy increases the non-dispatchability of power system, requiring fossil-based technologies to provide back-up capacity as dispatchable source. In a coal-based economy like China, it is coal-fired units that act as back-up capacity. This paper shows that increase of non-fossil energy generation is associated with higher heat rates of coal-fired units, which can be explained by the decreased operating hours for dispatching. This side-effect is sizeable, accounting for 13% of carbon mitigation from non-fossil energy. The extra fuel cost is estimated to be 10.9 billion US dollars. This paper thus calls attention to alternative technologies, such as large-scale storage, as dispatchable source.