Solid Oxide Fuel Cell - A Future Source of Power and Heat Generation

Abstract

Fuel cells are devices for electrochemically converting the chemical energy of a fuel gas into electrical energy and heat without the need for direct combustion as an intermediate step. The main advantages of fuel cells are that they rely on the high conversion efficiency and low environmental impact than traditional energy conversion systems. One promising fuel cell type, Solid oxide Fuel Cell, has all the components in the solid phase utilises nano-ceramic composite materials and operates at elevated temperatures in the range 500-1000°C. It has suitable perspectives to replace their classical counterparts for the distributed generation of electrical energy with small and medium power sources. The inherent advantages of such high temperature fuel cells are internal reforming of methane and waste heat production at high temperatures which lower the demands on the fuel processing system and lead to higher efficiency compared with low temperature fuel cells. Using natural gas as feed, an electric efficiency of more than 88% has been predicted. On the other hand, considerable research is going on to reduce the operating temperatures between 600°C to 800°C to increase life-time and thereby reduce costs. These can be achieved only by using electrolytes with proper ionic conductivity at the intermediate temperatures. In addition, this technology does not produce significant amounts of pollutants such as nitrogen oxides compared with internal combustion engines. Solid oxide fuel cells are seen as ideal energy sources in transport, stationary, and distributed power generators.