Biomass-Based, Small-Scale, Distributed Generation of Electricity and Heat Using Integrated Gas Turbine-Fuel Cell Systems

Abstract

The use of a biomass gasifier that drives a gas turbine integrated with a fuel cell, is a potentially very attractive way to generate electricity and heat with a high efficiency and very low emissions. The application of catalytic combustion systems can decrease the emissions even further. A number of technical and non-technical developments during the last 5 years have significantly enhanced the opportunities for small-scale, distributed power generation, especially for systems based on biomass fuels. These developments are: the liberalisation of the energy market, the growing needs for electricity and heat in developing countries, the increasing demand for ‘green’ or ‘sustainable’ electricity, the near-commercial availability of maintenance-low microturbine generator packages and developments in the field of high temperature fuel cells. Preliminary system studies have shown that the integration of the different subsystems needs careful evaluation in order to realise the expected high efficiencies. To enable the assessment of the technical feasibility of potentially attractive system designs, adequate, experimentally validated knowledge with regard to biomass gasification, pressurised combustion of the fuel gas and the gas cleaning steps is required. Possible system designs based on a combination of electrochemical and thermochemical fuel conversion steps are examined and analysed with regard to efficiency, emission and costs. A system design for application on commercial scale based on present day technology will be considered. At Delft University of Technology, a biomass gasifier has been set up and a conceptual design for a pilot system, to be tested in the slipstream of the Delft 1.5 MWth process development unit, will be presented. The process development unit is described in more detail in [Hoppesteyn, et. al., 1998] and [de Jong et. al., 1998]. In this study, it has been attempted to integrate an SOFC with an existing micro gas turbine that has not especially been adjusted for the integration with the SOFC.