20 March 2009 - RWE Power is starting to develop a high-temperature thermal storage facility for combined-cycle power plants (CCGT).
The integration of such a storage facility into the power plant process enables the supply of electricity and heat to be decoupled timewise. The process permits to "park" surplus heat produced during the day beyond the customer's demand and to provide it during the night when the gas turbine is not operating.
This separation is currently not possible in CCGT power plants which are operated in the combined heat-and-power mode (CHP) with the associated high degree of fuel utilisation and low level of CO2 emissions.
The project is to be taken forward in the next few years together with the companies ThyssenKrupp Xervon Energy, Paul Wurth Group and the Institut für Technische Thermodynamik des Deutschen Zentrums für Luft und Raumfahrt (DLR).
"We intend to widen the applications of efficient and resource-conserving cogeneration by deploying these power plants even more flexibly. Especially increasing, non-demand- driven capacities in the generation pool, for instance in growing offshore wind farms, impose greater flexibility requirements on our power stations," explained Dr. Johannes Lambertz, Chief Executive Officer of RWE Power.
Lambertz said: "CCGT power plants operated in CHP mode are often no longer driven by the power market, but usually by the heat market. Owing to this disadvantage, power plants with heat extraction have to continue operating even when demand for electricity is low in the public grid, for instance at night.
"The use of the innovative technology also improves the economic efficiency of CCGT power plants. This advantage is appreciated by our customers. In fact, many industrial plants and municipal utilities in particular have a strong interest in the development of the thermal storage facility," Lambertz went on to say.
The project development is expected to take approximately two and a half years. Once the development phases have been concluded successfully, the cooperation partners intend to erect a pilot facility with a capacity of 10 MWh. The cogeneration plant of RWE Power in Dortmund could be the potential site from 2011.
The preliminary studies already conducted confirmed the general technical and economic feasibility. The practicability of a CCGT power plant with integrated thermal storage depends on the availability of a cost-efficient, reliable and long-lived high-temperature thermal storage facility of a large commercial scale.
With ThyssenKrupp Xervon Energy, a partner has been found for the integration of thermal storage into the CCGT process, that can draw on many years of experience with the erection of CCGT/CHP plants.
"We are confident to develop highly flexible thermal-storage CCGT power plants to commercial maturity in this cooperation in a foreseeable period of time. Apart from new-build projects, the retrofitting of existing facilities is also an important option for us," said Hans-Josef Sandkaul, Managing Director of ThyssenKrupp Xervon Energy in Duisburg.
Know-how in respect of high-temperature thermal storage is contributed to the project by the Paul Wurth Group. "We have already applied similar schemes to supply hot air in the metal and glass industry. However, they have to be tailored to the specific requirements of a CCGT combined-cycle power plant," said Dr. Manfred Möller, Managing Director of Paul Wurth Refractory & Engineering GmbH, Wiesbaden.
Under the cooperation, DLR is taking charge of the thermal design of the heat storage facility, investigations of potential storage inventory materials in the laboratory and the operation of a small pilot-scale prototype.
"The development and testing of technologies for high-temperature storage using innovative materials are one of our core areas of expertise," explained Dr. Stefan Zunft of Deutsches Zentrum für Luft- und Raumfahrt in Stuttgart.