The Global Coal Atlas: Techno-Economic Analysis of Converting the World's Coal-Fired Power Plants into Thermal Storage Power Plants

As part of the Coal Atlas project, technical concepts were developed and analyzed for converting existing grid-connected coal-fired power plants into CO2-free thermal storage power plants (TSPP). The main goal of the analysis presented here is to create a collection of data that includes a forecast of decarbonization and CO2 avoidance costs for each of the existing coal-fired power plants worldwide.

In a TSPP, a high-temperature thermal storage is charged using renewable energy (Power-To-Heat). Optionally, additional firing with CO2-neutral fuels can be implemented. For discharging, the heat from the storage is converted into electricity and fed into the grid using the existing power block and grid connection (Heat-To-Power). This Power-To-Heat-To-Power storage is also known as a Carnot Battery. The storage converts fluctuating renewable electricity generation to power on demand.

The study examined configurations that combine high-temperature thermal energy storage with either electric heaters or high-temperature heat pumps for Power-To-Heat. While systems based on electric heaters represent a mature and cost-effective solution, heat pump–based systems can improve overall round-trip efficiency by upgrading low-temperature heat using electricity.

A comprehensive global database of approximately 7,000 coal power plants served as the foundation for this analysis. Based on detailed technical data available for selected reference plants, two representative plant configurations were modeled in Ebsilon Professional to obtain detailed thermodynamic and operational results. These Ebsilon reference models were then simplified and transferred into the DLR software greenius, enabling large-scale simulations for all approximately 7,000 coal power plants in the database. This allowed a consistent evaluation of the energy performance of each site under a typical daily operation profile (12 h charging / 12 h discharging). The technical results from these simulations were further processed in the DLR TEPET tool to perform a techno-economic assessment.

This work provides the first global-scale techno-economic assessment of converting the existing coal power fleet into sustainable, dispatchable thermal storage systems. The results were summarized in a fact sheet that was created for each plant. It includes technical results such as i.a. round-trip efficiency and annual yield as well as those obtained from the economic evaluation like capital expenditure for conversion (CAPEX), operating costs (OPEX) and levelized cost of electricity (LCOE). In addition, the CO2 avoidance potential and the associated costs were calculated. The data collection of these results is intended to serve decision-makers from industry and politics as an objective basis for a possible global conversion of existing coal-fired power plants into CO2-free TSPP. These approx. 7000 fact sheets are provided as annex to this study.