Feasibility analysis of decarbonizing coal-fired power plants with 100% renewable energy and flexible green hydrogen production

In the context of global decarbonization, China announced to peak its CO2 emission before 2030 and achieve carbon neutrality before 2060. The power sector dominates the total CO2 emissions in China, where coal-fired power plants are both the largest source of power generation and CO2 emissions, so exploring its decarbonized transition is essential to achieving the carbon neutrality commitment. To this end, this paper proposes a novel carbon-free retrofitting scheme for coal-fired power plants based on 100% renewable energy, hybrid energy storage system, and flexible green hydrogen production using energy curtailment, which can be technoeconomically feasible for practical applications. Then, the multi-regional and multi-temporal profitability of this retrofitting scheme is comprehensively assessed to confirm the proposed hypothesis via a life cycle economic optimization model. Taking the province-level regions in China as case studies, the assessment results reveal that the proposed retrofitting scheme is technically feasible in all investigated regions, and economically profitable in Jilin, Shanghai, Liaoning, and Heilongjiang regions with rich wind resource. Particularly, the optimal net present value of the proposed scheme in Jilin is 24.04 billion CNY, higher than the figure for carbon capture and storagebased retrofit (5.79 billion CNY) and even the non-retrofitted plant (9.28 billion CNY), confirming its economic superiority in specific regions. The cost breakdown in Jilin indicates that the flexible green hydrogen production using energy curtailment can additionally provide 106.3 billion CNY hydrogen trading revenue to recover the overall retrofitting cost (104.7 billion CNY), while the retrofitting scheme without electrolyzer will suffer a 44.17 billion CNY deficit owing to the oversized configuration. Moreover, the long-term profitability analysis shows that the proposed retrofitting scheme in Jilin can always achieve the best profitability from 2022 to 2050 despite the decline of projected hydrogen price, with the net present value ranging from 24.04 billion CNY to 1.12 billion CNY. Overall, this paper provides a techno-economically feasible solution for the decarbonizing transition of coal-fired power plants, and the proposed retrofit can be piloted in regions with rich renewable energy resources and mature hydrogen trading market.