Global Warming

312 Energy andtransport for thefuture

Figure 11.16A solar photovoltaic (PV) electrolytic hydrogen system.

would at the moment be several times that from fossil fuel sources.^69

As the technology for its further development progresses and as larger-

scale production becomes possible, the cost will undoubtedly reduce

substantially. If its attractiveness from an environmental point of view

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

one hundred 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^70 has been produced on Earth at levels up to 16 MW.

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

thirty years.