Supercritical CO2-power cycles for efficient heat utilization
With the transformation of energy systems taking place worldwide, the further development and expansion of dispatchable generation units and energy storage systems to maintain security of supply and system stability as well as heat supply must be driven forward. Due to the special properties of carbon dioxide above the critical point (31°C, 73.8 bar), there are advantages to using it in thermodynamic cycle processes. These cycle processes achieve higher efficiencies and a significant reduction in the size and complexity of the individual components. This enables the more efficient utilisation of industrial (waste heat), geothermal and solar heat sources as well as thermal energy storage systems. Heat sources that could not previously be utilised economically thus show potential for stable energy supply. However, there are a number of challenges and research requirements before commercialisation can be driven forward. For example, although turbomachines with supercritical CO2 (sCO2) are significantly more compact than water vapour turbines, the temperature remains at a high level and large amounts of heat must be recuperated internally using compact and cost-efficient heat exchangers. Furthermore, due to the high energy density, the aerodynamic optimisation of the turbomachinery is of particular importance. In addition, new types of improved sealing and bearing technologies must be developed or adapted. The high pressure load combined with high process temperatures places increased demands on the construction materials used, which must be qualified for this application. Finally, due to the originality of the sCO2 process, there is hardly any operating experience worldwide with regard to control and instrumentation in such plants.