Isopropanol-Acetone-Hydrogen chemical heat pumps for improved heat recovery from geothermal resources, A case study in China

This study focuses on geothermal energy utilization through multi-objective optimization of Isopropanol-Acetone-Hydrogen chemical heat pump (IAH-CHP). In this paper, IAH-CHP coupled with medium-low temperature geothermal heat source simulation was constructed. China, the world's largest carbon emitter, was used as a case study to highlight environmental benefits. Comparative analysis was conducted between carbon emissions and investment of chemical heat pumps with other common heating equipment in different buildings. The results show IAH-CHP system has higher initial investment costs, however, their CO₂ emissions are significantly lower. The results of multi-objective analysis demonstrate the system can operate under a Pareto (multi-objective) optimal scheme. Under this plan, the levelized cost of heat (LCOH) is only 0.12 USD/kJ, and the carbon emissions are as low as 4.97 tons/year with a coefficient of performance (COP) of 7.4. Compared with a single-objective optimal solution, 8.12 tons of carbon emissions and LCOH of 0.15 USD/kJ could be achieved. Applying IAH-CHP system to China to replace original coal-fired heating solution can achieve annual carbon emission reduction of more than 5 million tons in areas with medium and low temperature heat sources.