Engines versus electrons: the future of power production

The demands for energy are increasing as countries become richer, and if al l mankind achieved the per capita energy consumption of the United States t hen the total energy consumption of the world would rise by a factor of abo ut 4.5. This would make a large demand on fuel supplies and probably increa se pollution beyond a sustainable level. This paper examines the limits to the theoretical efficiency of power generation, including both heat engines and fuel cells, and demonstrates that thermal efficiencies of above 60 per cent are achievable in each case if combined plants are used. It is shown that the fuel cell has benefits over the heat engine when the plant operate s for a significant time at low load.