Bringing fusion power to the grid

Nuclear fusion, the sustainable energy source that for many decades we have been promised is only a few decades away, might now be only a few decades away. So confident are the technical experts and policymakers that the European Fusion Development Agency (EFDA) has published a roadmap outlining its plans for supplying fusion power to the grid by 2050.

Fusion involves forcing atoms together rather than splitting them apart as in the heat generating radioactive fission reactions in existing nuclear power plants. Achieving fusion is not in itself a problem. Fusion reactions can be explosive, as in nuclear weapons, or controlled in reactor vessels, most often with extremely hot gases contained within magnetic chambers.

Initiating fusion is a relatively simple process given sufficient input energy for the positively charged protons within atoms to overcome the strong repulsive force between them. The challenge is in sustaining the reaction in a controlled manner. With magnetic confinement fusion reactors the particles have such high energy and are moving so fast that they leak out of the reactor chamber, taking their energy with them and cooling the remaining plasma. The end result is that no net energy is produced.

Developing fusion power is no longer dependent on achieving major scientific breakthroughs, but rather refining the physics and reactor engineering. Several experimental fusion reactors are in operation around the world, or will soon come online. The latest of these is the multinational project ITER, based at Cadarache in France. When ITER becomes operational in 2020 it will be the first fusion reactor to produce a net surplus of energy: 500 megawatts from a 50 megawatt input.

What the EFDA has done is draw up a roadmap covering three periods from now until 2050, with clear milestones set out for each. From now until 2020 the primary focus will be on getting ITER up and running. The second period will see the fine tuning of ITER, maximising its exploitation and preparing for the construction of a demonstration power plant that supplies electricity to the grid and ultimately our tea kettles. The third period defined in the roadmap will see the building and operation of a prototype fusion power plant.

That is the plan, and, barring major technical gremlins or international funding crises, it should happen. There appears to be sufficient political will and international cooperation behind the project, and the need for sustainable high-load electrical power sources that will take us beyond the fossil fuel age is acknowledged. Existing nuclear technologies can only ever be a stopgap.