Solar thermal power plants enable electricity generation that covers the actual demand. The main reason for that is the independency from the fluctuating solar irradiation, due to integrated thermal storages or partly fossil hybridization. They have the potential to be the base-load power plant in an energy system based on renewable energy. In the development of solar thermal power plants, the fundamental objectives are to keep the costs low, the efficiency high and the energy generation based on the demand, and there are several available technologies to actualize that.
High-efficiency steam turbine processes
Concentrated solar irradiation is used in salt power towers to heat a molten salt mixture from 290°C up to 560 to 580°C. The molten salt is then fed to a steam boiler which is used to operate a power plant process with a steam turbine. The molten salt is also used as storage medium and may be stored in a cold and hot tank. This technology enables cost-efficient integration of thermal storages with high capacity and is particularly suitable for large plants of the size 100 MWe or larger. Implementation of solar energy in supercritical steam processes is one potential area of development for solar power towers that promises improved process efficiency by increasing the receiver temperature moderately. In the conventional part of these processes (steam boiler, turbine, generator), only slight improvements of the efficiency are to be expected. Though, the potential of developing and improving the integrated system parts such as the heliostat field, receiver and solar high-temperature circuit is big. One of the major ongoing projects at DLR is the optimal integration of power plant components and the optimal design of the solar section.
Solar gas turbine power plants
In solar power plant processes based on gas turbines, the air used as working medium is heated to high temperatures by concentrated solar radiation. DLR plays a leading role in the further development of the present receiver technology that now enables temperatures up to 1000°C. The use of the solar irradiation is characterized by:
Activities at DLR
The main focus of the research is the complete system of heliostats, field set-up, receiver, heat transfer medium, storage, power plant process and operation strategy. Therefore, the single components are evaluated from their impact on the complete system. The fields of activities at DLR are:
Furthermore, research is made on how other types of renewable energy supply may be combined with solar thermal plants, for instance by solar CHP with cooling or with additional photovoltaic modules (PV) in PV-CSP combo plants.