Nuclear fusion is still decades away
The breakthrough humanity needs the most – sustainable nuclear fusion power that produces clean, virtually limitless energy – won’t arrive in the 2020s, but we’ll get closer. The old joke in physics is that nuclear fusion is the technology that always exists 30 years in the future. Finally, that 30-year timeframe looks realistic, thanks to the billions being invested in fusion and the construction of large experimental fusion reactors.
Fusion power poses one of the greatest engineering challenges – building devices to replicate the nuclear reactions that occur in the Sun and the stars and capturing the resulting energy. It is different from existing fission nuclear reactors, which split atoms to produce energy but create dangerous nuclear waste in the process.
It involves generating massive temperatures – more than 100 million degrees Celsius, creating the conditions for hydrogen atoms to fuse, releasing energy.
Superheated plasma created in the reactor has to be held in place under huge pressure created by magnetic fields. Gravity does that job for the Sun and the stars. Many test reactors around the world, including the one at MIT in Boston I visited a few years ago, can undertake the reactions. But none are yet capable of sustaining a reaction that creates ‘‘net energy’’ – more energy than is required to produce the reaction.
The world’s largest experimental nuclear fusion reactor, Iter, is under construction in France and on track to begin producing plasma in 2025. But it isn’t expected to produce fusion power until 2035. China’s ‘‘artificial sun’’, the doughnut-shaped Tokamak test reactor, will be operational this year and will give scientists valuable data. Meanwhile, the UK is investing £220 million (NZ$ 435m) in nuclear fusion reactors. That’s the difference – serious money is now going into nuclear fusion.
If fusion power was available now, we’d have a shot at decarbonising the global economy to the extent we need to avoid dangerous climate change later this century. But fusion sadly won’t help us tackle climate change. Instead, by 2050, nuclear fusion could be the primary energy source of a post-carbon world. I hope we limit the damage we do to the planet in the intervening decades.