Nuclear option

It is a normal February day in Culham. The quiet village on the banks of the Thames is the picture of English countryside life: neat hedgerows, a parish church, grazing cattle. 

But just a couple of miles away is one of the biggest scientific experiments ever carried out. It is Culham Centre for Fusion Energy, home to one of the world's most advanced nuclear fusion reactors, JET. And yesterday, it made a huge breakthrough. In the space of five seconds, it produced 11 megawattsA unit of power, equal to one million watts. of energy - enough to boil 60 kettles. 

It might not sound like much, but it is more than double what has been achieved in previous tests. And it could open the door to a new form of clean, efficient energy.

Fusion is the holy grail for nuclear scientists. Today's nuclear power is created through fission. Uranium atoms are split apart into lighter elements, releasing energy in the process. Fission relies on environmentally damaging mining, causes radioactive wasteNuclear fission uses uranium which stays radioactive. Fusion can only take place in the unique conditions of the reactor. and can lead to catastrophic accidentsThere have been several nuclear crises including the 1986 Chernobyl incident in Ukraine and the 2011 Fukushima disaster in Japan.. 

By contrast, fusion is almost totally clean. It takes place when two nuclei collide and combine to become a heavier element. We see the process every day: the sun glows as a result of hydrogen atoms on its surface continually fusing into helium. 

Recreating this process on Earth means potentially unlimited supplies of low-carbon, low-radiation energy. But it has proved difficult. Fusion was first achieved in 1951. It took until 1991 for scientists to achieve a controlled release of fusion power. So far, all attempts have used up far more energy than they produced. 

Temperature has been a major hurdle. A gas has to reach 150 million C to create a reaction. Using pioneering technology scientists at Culham have reduced the temperature to about 300C - similar to that of a car engine. Yesterday's breakthrough has huge implications. 

A working fusion reactor could revolutionise how we create energy. Fusion can turn 1kg of fuel into 1,500 megawatts of electricity - enough to power over a million houses for a year. It would take about 10,000 tonnes of coal to do the same.

Unlike fossil fuels, fusion is carbon-free and does not produce greenhouse gasses. And unlike nuclear fission, it does not produce nuclear waste. As Nobel Prize-winning physicist Stephen Hawking put it: "It would provide an inexhaustible supply of energy, without pollution or global warming."

But there are snags. Fusion is efficient, but it is non-renewable. And there remains much work to be done: the Culham team plans to create a prototype fusion plant in the 2040s. This may not be enough time to save us from climate change. As one journalist puts it: "Fusion is not a solution to get us to 2050 net-zero. This is a solution to power society in the second half of this century." 

Is fusion our best hope for the climate?

Yes: Fusion does not rely on specific natural conditions. It might be tough to achieve, but it is the only solution to fix a problem as large as the climate crisis. We have to make it work. 

No: Just because there was a breakthrough this week, this does not mean fusion can magically fix our problems. We still have no guarantee that it will ever work efficiently. 

Or... It is one solution of many. We know that fusion could provide the energy we need to power the world. But we also know that it is not working yet. Right now, we need to reduce our environmental impact with the tools we have already - renewable energy.