We already live in a world powered by nuclear fusion. Unfortunately the reactor is 150 million kilometres away and we haven’t worked out an efficient way to tap it directly. So we burn its fossilised energy – coal, oil and gas – which is slowly boiling the planet alive, like a frog in a pan of water.
Recreating the sun on Earth would go a long way to solving that problem, but it is a biggie. Research started more than 60 years ago; the leading fusion reactor design, the tokamak, is half a century old. Tokamaks trap heavy hydrogen isotopes inside a doughnut-shaped magnetic field, heating and squeezing the plasma so that deuterium and tritium fuse to release energy. After testing a series of increasingly large tokamaks, fusion researchers agreed 10 years ago to build a huge one in France called ITER.
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If everything goes to plan – which it almost certainly won’t – in 2035 ITER will produce 500 megawatts of energy for a few hundred seconds. That will make it the first fusion reactor to produce more energy than it takes to operate.
Even then, two big hurdles will remain, says Mickey Wade, vice president of General Atomics and director of the US-based DIII-D fusion programme. One is developing materials that can withstand prolonged exposure to plasmas. The other is sustaining the intense magnetic fields needed to confine the plasma.
Cracking all three would be an epoch-making breakthrough. Fusion would largely free us from fossil fuels, delivering clean and extremely cheap energy in almost unlimited quantities.
Or would it? Fusion power would certainly be cleaner than burning fossil fuels, but it wouldn’t be carbon neutral. The reactors do not emit carbon directly, but construction, fuel production and waste management inevitably have carbon footprints of their own. Fusion also creates radioactive waste, albeit a type that decays in decades rather than hundreds or thousands of years.
Nor will fusion power be too cheap to meter. The reactors are astronomically costly to build – ITER has ballooned to more than €20 billion. Nobody will spend that sort of money if they can’t recoup their investment. But once up and running, operating costs will be modest. The oceans contain enough deuterium to fuel fusion reactors for tens of thousands of years. Tritium is extremely rare in nature but can be easily made from lithium, which is also abundant.
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Could the whole world run on fusion power? In principle yes, but it is unlikely in practice. Operators will want to run fusion plants as much as they can to recover their investment, so they will probably generate mostly baseload power. Peaks in demand will probably have to be met by energy storage technologies such as ultracapacitors, charged up by solar and wind. We will also have to think up new ways to power planes and other technologies that cannot run directly on grid power.
Fusion could still revert to type and remain a future technology 60 years from now. Solar and wind are unlikely to satisfy all of our needs. In that case, we may have to default to nuclear fission, with all of its downsides – accidents, long-lived waste and weapons proliferation worries. Superconductivity (see “The world in 2076: Goodbye electicity, hello superconductivity“) and geoengineering (see “The world in 2076: We fixed the climate but still face turmoil“) may come to our rescue. But all things told, we really need plenty of home-made sunshine by 2076.
This article appeared in print under the headline “What if… We crack fusion and solve our energy problem?”
