Technology for the longer term

This chapter has concentrated mostly on what can be achieved with available and proven technology during the next few decades. It is also interesting to speculate about the more distant future and what relatively new technologies may become dominant during the twenty-first century. In doing so, of course, we are almost certainly going to paint a more conservative picture than will actually occur. Imagine how well we would have done if asked in 1900 to speculate about technology change by 2000! Technology will certainly surprise us with possibilities not thought of at the moment. But that need not deter us from being speculative!

There is general agreement that a central component of a sustainable energy future is the fuel cell that with high efficiency converts hydrogen and oxygen directly into electricity (see box). In the fuel cell the electrolytic process of generating hydrogen and oxygen from water is reversed - the energy released by recombination of the hydrogen and oxygen is turned back into electrical energy. Fuel cells can have high-efficiency of 50-80% and they are pollution free; their only output other than electricity and heat is water. They offer the prospect of high-efficiency, small-scale power generation. They can be made in a large range of sizes suitable for use in transport vehicles or to act as local sources of electrical power for homes, for commercial premises or for many applications in industry. Much research and development has been put

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Figure 11.24 Schematic of a hydrogen-oxygen fuel cell. Hydrogen is supplied to the porous anode (negative electrode) where it dissociates into hydrogen ions (H+) and electrons. The H+ ions migrate through the electrolyte (typically an acid) to the cathode (positive electrode) where they combine with electrons (supplied through the external electrical circuit) and oxygen to form water.

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