The solid oxide fuel cell [SOFC] is an electro-chemical engine that transforms the chemical energy potential of a fuel into electricity directly, without an intervening thermodynamic heat cycle. The SOFC is distinguished from other fuel cells by its high temperature of operation [circa 1000 degC] and its all solid state nature. Siemens Westinghouse has pioneered the tubular SOFC and a seal-less stack or generator design incorporating in-stack reformation for natural gas. Tubular SOFCs have demonstrated long life and very low degradation rates both in the laboratory and in pipe line natural gas fuelled, un-manned, power systems deployed in the field. The most successful SOFC demonstration to date is a 100 kWe combined heat and power system which has operated for over two years exporting power to the grid with an electrical generating efficiency of over 46% [net ac/LHV]. An SOFC may be combined synergistically with a gas turbine to yield a pressurized SOFC/gas turbine hybrid cycle power system that in simple form can achieve 60% electrical generating efficiency. The first such system has been tested. In a SOFC reheat cycle configuration, electrical generation efficiencies of 70% appear practical. The principles of operation, the nature of the technical challenges, an overview of experience and accomplishments, and a view of the future will be presented.

This page updated August 23, 2001