Fuel Cell Technology

Abstract

Since fossil fuels are likely to remain the main energy supply in the near future, conservative energy use and the application of highly efficient energy conversion processes are still the only way to alleviate the CO₂-problem. It has long been recognized that «cold burning» of fuels in an electrochemical «fuel cell» results in an energy conversion with potentially very high efficiency. Fuel cells were first put to work with pure hydrogen as the fuel in space technology in the 1960’s. The principles of the technology were developed during that time. The subsequent developments have focussed on terrestrial applications and on systems compatible with the use offossil fuels. There is a large number of possible combinations of electrode and electrolyte materials to build a fuel cell. The five major types are discussed in the present article. The hitherto most advanced system is the phosphoric acid fuel cell (PAFC), which can be operated on reformed natural gas as the fuel; PAFC technology has been demonstrated on a 4.5 MW scale. More advanced fuel cell systems operating at temperatures above 600 °C are expected to become an efficient and clean alternative to the established thermal processes in the production of electricity from coal. Fuel cell types operating at low temperatures are expected to play a future role in decentralized energy use, transportation, and «hydrogen technology».