Fuel cells are one of the cleanest and most efficient technologies for generating electricity. Since there is no combustion, there are none of the pollutants commonly produced by boilers and furnaces. For systems designed to consume hydrogen directly, the only products are electricity,water and heat. Fuel cells are an important technology for a potentially wide variety of applications including on-site electric power for households and commercial buildings; supplemental or auxiliary power to support car, truck and aircraft systems; power for personal,mass and commercial transportation; and the modular addition by utilities of new power generation closely tailored to meet growth in power consumption. These applications will be in a large number of industries worldwide¹.

What is Fuel Cell?

Around 170 years ago, British scientist William Grove discovered the basic principles of fuel cells by reversing water electrolysis to generate electricity from hydrogen and oxygen. This process still works today. One definition for fuel cell is that "A fuel cell is an electrochemical device that continuously converts chemical energy into electrical energy (and some heat) for as long as fuel and oxidant (air or oxygen) are supplied"². Fuel cells therefore exhibit similarities both to batteries and to engines. Fuel cells, like batteries, are using electrochemical processes to produce electricity. However, unlike batteries, fuel cells can work continuously consuming a suitable fuel. Unlike batteries or engines, fuel cells operate quitely and efficiently and when hydrogen is used as fuel the only byproduct is drinking water while you produce your power. These devices are so called zero emission engine due to this marvellous feature of the fuel cells.

In terms of thermodynamics, the most explicit difference of fuel cells is that thermal engines are limited by Carnot efficiency, while fuel cells are not. Though fuel cells could, in principle, process a wide variety of fuels and oxidants, of most interest today are those fuel cells that use common fuels (or their derivatives) or hydrogen as a reductant, and ambient air as the oxidant.

References:

1. A.J. Appleby, F.R. Foulkes, November 2004, "Fuel Cell Handbook (7th Edition)", U.S. Department of Energy Office of Fossil Energy National Energy Technology Laboratory, Morgantown, West Virginia

2. G. Hoogers, 2003, "Fuel Cell Technology Handbook", CRC Press, United States of America