Plans call for the construction of a megawatt-class demonstration plant, with the necessary groundwork scheduled to be completed by 2008. This will form the basis for the construction of an initial, small pilot plant that will be followed by the planned fuel-cell hybrid plant with an installed capacity of one megawatt, in 2012.

The efficiency of the hybrid process is significantly greater than that of modern gas- and steam-turbine power plants that reach an efficiency of about 60%. This high efficiency is to be achieved by combining a high- temperature fuel cell with a gas turbine in the planned hybrid plant in order to make more effi-cient use of the fuel and reduce emissions.

The project is scheduled to run for an extended period, and involves intensive background research to obtain the most favourable operation of stationary fuel cells in conjunction with gas turbines, making hybrid solid oxide fuel cells (SOFC) a viable alter- native for commercial plants. After successful completion of the project, this hybrid technology will become available roughly a decade sooner than expected by experts today.

In solid oxide fuel cells, an electrochemical reaction converts fuel energy directly and efficiently into electricity and heat. In a hybrid power plant, the hot exhaust gases exiting the fuel cell are fed into the gas turbine, thereby reducing or totally elimi-nating the fuel consumption of the turbine. The gas turbine makes it possible to operate the fuel cell at increased gas pressure, which makes it more efficient.

On the way toward realisa- tion of the first megawatt demonstration plant using hybrid tech- nology, Siemens will initially supply a high-temperature SOFC with a capacity of five kilowatts.

“We look forward to laying the groundwork for broad applica-tion of hybrid fuel-cell technology in distributed and centralised power generation in a long term,” says Siemens Power Generation group executive management member Norbert Koenig. The German Aerospace Centre (DLR) will operate and analyse the SOFC.

“We are pleased to have found in Siemens a competent partner for this maximum-efficiency future technology,” says EnBW vice-president of engineering Dr Thomas Hartkopf. “This technology will take us a big step forward in our effort to extract more electricity from less fuel, and to bring emissions down to lower levels.”

Since 2001, EnBW has opera-ted a Statewide programme to provide funding for a wide variety of fuel cells that are being used directly by customers and part- ners in real-world power applications – something that has allowed EnBW to draw corresponding technical experience from the operation of more than 20 plants. Initial experience with biogas-powered fuel cells has also been gained since 2006.

During the initial phase of the project, which is scheduled to run for three years, the individual components will serve as the basis for development of an operating concept and a corresponding simulation model. The associated control concept will be developed by the Institute for Aviation Engineering. The test components them- selves will be coupled in the next phase of the project, starting in 2009, and the configuration will be optimised, beginning in 2012.

To serve the aim of this project, a special research working group was established at the University of Stuttgart. With the continued support of the Helmholz Association of German Research Centres, it bundles the resources of the German Aerospace Centre, in Stuttgart, and the University of Stuttgart. Spokesperson of the research group is Professor Aigner of the Institute for Combustion Engineer-ing of the DLR, which will make available the gas microturbine and laboratory facilities operated by the institute.

The Siemens Power Trans-mission and Distribution Group (PTD), headquartered in Erlangen, Germany, is a global player in its market sector. As a product supplier, system integrator, solution designer and service provider, Siemens PTD ensures – for utilities and indus- try alike – the efficient and reliable transmission of electrical energy from the power plant to the consumer. With a worldwide workforce of about 25 850 and operations in nearly 90 countries, PTD had sales of €4,3-billion in fiscal 2005.