Power from nuclear fusion

When at extremely high temperatures the nuclei of hydrogen (or one of its isotopes, deuterium or tritium) are fused to form helium, a large amount of energy is released. This is the energy source that powers the Sun. To make it work on Earth, deuterium and tritium are used; from 1 kg, 1 GW can be generated for one day. The supply of material is essentially limitless and no unacceptable pollution is produced. A temperature of 100 million degrees Celsius is required for the reaction to occur. To keep the hot plasma away from the walls of the reaction vessel, it is confined by strong magnetic fields in a 'magnetic bottle' called a Tokamak. The challenges are to create effective confinement and a robust vessel.

Fusion power has been produced on Earth at levels up to 16 MW.69 This has generated the confidence in a consortium of countries to build a new power-station-scale device called ITER capable of 500 MW with the object of demonstrating commercial viability. If this is successful, it is estimated that the first commercial plant could be in operation within 30 years.

drive towards energy efficiency becomes more vital, many of these will find appropriate applications.

Most of the technology necessary for a hydrogen energy economy is available now.68 If its attractiveness from an environmental point of view were recognised as a dominant reason for its rapid development, a hydrogen economy could take off more rapidly than most energy analysts are currently predicting.

Iceland is a country that is in the forefront of the development of a hydrogen economy and aspires to be largely free of the use of fossil fuels by 2030-40. Much of its electricity already comes from hydroelectric or geothermal sources. The first hydrogen fuel station in Iceland was opened in April 2003 and several buses powered by fuel cells are its fi rst customers.

Finally, in this section looking at the longer term, there is the possibility of power from nuclear fusion, the energy that powers the Sun (see box). If this can be harnessed, virtually limitless supplies of energy could be provided. The result of the next phase in this programme of work will be watched with great interest.

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