Co-optimization of decarbonized operation of coal-fired power plants and seasonal storage based on green ammonia co-firing

Abstract

Coal-fired power plants (CFPP) can provide significant inertia and flexibility support for power systems with a high share of renewable energy (RE). The ammonia–coal co-firing technology can effectively reduce carbon emissions (CE) from CFPP. We propose a low-carbon power supply and multi-timescale energy storage system in combination with this technology. The system consists of batteries, fuel cells and the CFPP equipped with the ammonia–coal co-combustion module. It can also cope with short and long term fluctuations in RE. We use the Mixed Integer Linear Programming method to construct an optimization model for this system. We then set up six sub-cases according to the power systems in Texas, USA. Based on weekly and annual simulations of these cases, we analyze the economic and environmental performances of the proposed system with different RE shares, as well as exploring the characteristics of different energy storage methods. Compared to batteries or fuel cells only scenarios, CFPP configured with green ammonia co-firing can significantly reduce the total operating cost (TOC), CE and RE curtailment. We use the rolling horizon optimization method to simulate and calculate the distribution of ammonia storage levels throughout the year. The ammonia storage levels are high in spring and autumn and low in summer. Finally, the sensitivity and efficiency analysis of the proposed system is carried out. As far as ammonia co-firing technology allows, the higher the maximum ammonia–coal mixing ratio, the lower TOC, CE and RE curtailment. This phenomenon is more significant at a higher RE share. The overall efficiency of green ammonia synthesis and combustion for power generation is around 13.92%. It can work in synergy with batteries and fuel cells to improve efficiency and reduce the marginal cost of long-term energy storage.