A global "hydrogen economy", in which energy is provided by hydrogen instead of fossil fuels, has long been dreamed of as a way of ending our dependence on coal and oil. In such a world, fuel cells would replace the internal combustion engines in cars and the steam turbines in power stations as the means of turning chemical energy into useful power. Rather than burning carbon-based fuels and therefore releasing carbon dioxide, fuel cells convert the chemical energy of hydrogen directly into electricity, producing only water as a by-product. Furthermore, since a fuel cell is not subject to the same thermodynamic constraints as a heat engine it can be made much more efficient than an internal combustion engine.
Spurred on by the promise of a clean, efficient engine, almost all leading car manufacturers – including General Motors, DaimlerChrysler, Ford and Toyota – are researching and developing fuel cells, with worldwide tests of thousands of fuel-cell-powered cars and buses having racked up almost three million kilometres. Meanwhile, electronics giants like Toshiba and Samsung, as well as smaller start-up companies, are working towards micro-fuel-cell technology to replace the batteries in power-hungry mobile phones and laptop computers. And in another aspect of the hydrogen economy, much larger stationary fuel cells could play a crucial role in decentralizing electrical power supplies.
While there are significant doubts about how we can actually make the transition to a hydrogen economy, these mostly concern the necessary infrastructure – i.e. finding cost-effective ways to generate, transport and store hydrogen. In the mean time, however, researchers are trying to develop fuel cells that can compete with the combustion engine.
In the July issue of Physics World, Michael Eikerling, Alexei Kornyshev and Anthony Kucernak describe how fuel cell technology has advanced, from the first practical cells in the late 1950s to the latest efficient designs.
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