The case for fusion

Professor Steven Cowley, Head of the Culham Centre for Fusion Energy discusses the most recent development in the field of nuclear fusion, as well as the growing need for mature fusion technology and the importance of sustained funding from governments and other large institutions.

The protracted saga of the Gulf of Mexico oil disaster has brought the need for cleaner energy sources back into sharp focus. As he toured the polluted beaches of the southern United States, President Barack Obama branded the spill an “environmental 9/11” and vowed to “move forward in a bold way in a direction that finally gives us the kind of future-oriented energy policy that we so vitally need.” But as the clean-up cost reaches US$2bn, a shortfall of a similar amount is jeopardising the future of the ITER project. A project that could transform the energy landscape and break the world’s dependence on fossil fuels.

The ITER nuclear fusion experiment is an international collaboration to turn the process that powers the stars into a viable method of generating electricity. It is finally ready for construction after two decades of political and financial wrangling. However, the escalating cost of the project is posing a new threat. Rises in commodities prices, additional infrastructure at the site at Cadarache in France, and major design changes have combined to almost treble the initial estimate to €13bn. The situation appears to have stabilised as the European Union, which as the host of ITER foots 45% of construction costs, has found an extra €1.4bn from its budget to keep the project alive. ITER is the first industrial-scale fusion device and an essential step towards clean fusion power. This is surely a prize worth paying for.

Fusion is one of the most promising long-term energy options: a source of carbon-free baseload power, with almost limitless supplies of fuel distributed around the globe. Deuterium and tritium, two types of hydrogen, are the chosen fuels for the fusion furnace. There are literally oceans of deuterium – it accounts for one in every 6500 hydrogen atoms in seawater. Tritium is not a naturally occurring material, but can be made (“bred”) from lithium, which is abundant in seawater and in the Earth’s crust. Fusing the two fuels releases so much energy that one kilogram of deuterium and tritium will produce the same energy as 10 million kilograms of fossil fuels. Or to put it another way, with the deuterium from a bathtub of water and the lithium from a laptop battery a fusion reactor could supply the average European resident’s electricity for 30 years.

Fusion also has crucial environmental advantages. The only by-product of fusion is helium, a harmless inert gas commonly used to inflate balloons. Admittedly the tritium fuel is radioactive, and neutrons from fusion activate the structures of the reactor.  However the short half-lives of tritium and the activated structural materials will ensure that the waste can be consigned to landfill within a century, or even recycled for use in a new fusion plant. Furthermore, the tiny amounts of fuel involved (only a hundredth of a gram, the weight of a postage stamp, is inside the reactor at any one time) mean that an accident requiring the evacuation of the surrounding area is impossible and that security risks are much reduced.