Economy and flexibility of a steam cycle with supercritical CO2 instead of water
Can the use of supercritical CO2 significantly improve the efficiency, cost-effectiveness and flexibility of thermal power plants and solar thermal power plants in particular? Researchers from the Institute of Solar Research, the Technical University of Dresden and the Helmholtz Centre Dresden-Rossendorf are investigating these questions together with the industrial partner Siemens Energy as part of the CARBOSOLA research project. For this purpose, they are comparing the economic efficiency of an sCO2 steam cycle with that of a modern water-steam cycle. The findings of the Carbosola project will also be used to facilitate the development of components and systems for an sCO2 power plant unit in commercial solar thermal power plants.
Various studies on the use of sCO2 in nuclear power plants, gas turbine combined cycle power plants and also in solar thermal power plants show potential benefits, but are often based on rough cost estimates. The technology itself has not yet been brought to market maturity for any power plant application.
Schematic of a CSP power plant with sCO2 power block using particle technology. Source: DLR
The focus of Part 1 of the project is on the techno-economic viability of sCO2 power cycles with two different heat sources:
The aim is to match components and process parameters in such a way that the lowest electricity production costs result. To achieve this, performance and cost models are being developed and simulated under various assumptions as part of the project. This will allow the impact of changes to the plant on the LCOE to be calculated and compared with the state of the art.
In part 2 of the project, the project participants are designing and constructing a powerful sCO2 test stand in order to be able to verify the results from simulation and analysis in practice. This will make it possible to test components for sCO2 processes under the same operating conditions as in commercial power plants (up to
650 °C and 300 bar). The first stage of the plant will have a maximum thermal output of 200 kilowatts. In addition, a multi-megawatt sCO2 demonstration loop is being designed to further advance the technological maturity of the overall system.
The researchers at the DLR Institute of Solar Research are responsible for the techno-economic evaluation of sCO2 loops for high-temperature CSP plants. Together with the project participants from Siemens Energy, they are developing thermodynamic models, establishing cost correlations for sCO2 components as well as
for CSP systems and investigating improvements to components and processes that have the potential to reduce energy costs.
Technische Universität Dresden