Title: Combined fuel cell–gas turbine plant for highly efficient power generation from renewable energy sources

Authors: Michael Monsberger, Viktor Hacker, Simon Fraser, Wolfgang Sanz, Florian Luckel, Herbert Jericha

Addresses: Christian Doppler Laboratory for Fuel Cell Systems, Graz University of Technology, Steyrergasse 21, A-8010 Graz, Austria. ' Christian Doppler Laboratory for Fuel Cell Systems, Graz University of Technology, Steyrergasse 21, A-8010 Graz, Austria. ' Christian Doppler Laboratory for Fuel Cell Systems, Graz University of Technology, Steyrergasse 21, A-8010 Graz, Austria. ' Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Infeldgasse 25, A-8010 Graz, Austria. ' Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Infeldgasse 25, A-8010 Graz, Austria. ' Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology, Infeldgasse 25, A-8010 Graz, Austria

Abstract: The impact of renewable energy sources on today|s energy supply substantiates the importance of hydrogen as an energy carrier. Hydrogen can be directly produced from solar energy and is considered a promising technology for temporary storage of electrical energy from wind turbines and photovoltaic systems. The generation of electrical energy from stored hydrogen requires highly efficient systems such as the so-called H2-Graz-Cycle, which is discussed in this paper. The H2-Graz-Cycle is a closed steam process based on the stoichiometric combustion of oxygen and hydrogen. It is shown that efficiencies of up to 51% can be achieved with the H2-Graz-Cycle even with small output powers in the range of 1.35 MWel. The process is thus particularly suitable for decentralised applications. It is further shown that the cycle efficiency can be significantly increased to a level of 75% by integrating a high temperature fuel cell into the cycle.

Keywords: Graz cycle; high temperature fuel cells; hydrogen storage; photovoltaics; renewable energy sources; solid oxide fuel cells; SOFC; wind power; wind energy; gas turbines; closed steam process; stoichiometric combustion; oxygen; hydrogen; energy storage.

DOI: 10.1504/IJETP.2007.014737

International Journal of Energy Technology and Policy, 2007 Vol.5 No.3, pp.307 - 318

Available online: 06 Aug 2007 *

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