Environmental considerations

The fuel cell is designed to consume hydrogen as fuel. A fuel cell using hydrogen has very little environmental impact since the product of the reaction is water, and water alone. The overall environmental effect of the fuel cell, therefore, depends upon the source of the hydrogen. Today most is derived from natural gas, but it could also be generated by gasification of coal or from various biomass sources. The environmental impact of each of these technologies then becomes the determining factor.

Even so, fuel cells are probably the most benign of all the power generation technologies to use fossil fuels. The levels of both sulphur and nitrogen oxide emissions they produce are extremely low, as are the particulate emissions. They are also quiet compared to the rotating machines which are normally used to generate electricity. Unit efficiency is generally higher than the efficiency of the equivalent rotating machine, so carbon dioxide emissions are proportionally lower too.

Fuel cells offer high efficiency independent of their size. A 250-kW unit will operate at exactly the same efficiency as a 200-MW power station. They also have good part-load efficiency. This makes them particularly attractive for distributed generation applications since most heat-engine-based small generating systems are less efficient than their larger relatives.

Fuel cells can easily be installed in urban areas, where population densities are high. Small, efficient units can be placed adjacent to buildings where waste heat generated by the plant can be used for heating and hot water. The water from a fuel cell can even be used as drinking water, such is its purity.

In the future it may be possible to generate hydrogen directly using renewable energy technologies. This will form the basis of a fuel economy in which hydrogen is employed as the primary means of storing and transporting energy. The fuel cell will form a key component of such a hydrogen economy, should this evolve. Fuel cells can turn hydrogen into electricity extremely efficiently, usually more efficiently than they can exploit natural gas. This will place them at the forefront of generation technologies if hydrogen becomes the fuel of choice later this century.

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