Can nuclear fusion save the planet?

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Nuclear fusion’s supporters describe it as the “holy grail” of clean energy: a technology that could theoretically provide near limitless, zero carbon power.

Fusion produces no long-lived radioactive waste, emits no carbon and has the potential to produce vast amounts of energy. Now scientists are racing to find a way to turn a century of experiments into a commercially viable power source.

How does it work?

Nuclear fusion is the reaction that powers the sun. It involves heating two hydrogen isotopes — normally deuterium and tritium — to such extreme temperatures that the atomic nuclei fuse, releasing helium and vast amounts of energy in the form of neutrons.

British scientists fused deuterium and tritium for the first time in a particle accelerator in 1934. Then Soviet physicists in the 1950s developed the first fusion machine, called a tokamak, which used powerful magnets to hold the isotopes in place as they heated them to temperatures hotter than the sun. Known as magnetic confinement fusion, this approach remains the most common, although there have been many advances.

Most groups building tokamaks today use high-temperature superconductors to increase the power of the magnets. Others are aiming to build a type of tokamak called a stellarator, which has a twisted structure that they say should produce a more stable reaction.

An alternative approach to fusion, known as inertial confinement, involves firing a projectile or lasers at a tiny capsule of deuterium-tritium fuel to spark an implosion that heats the isotopes until the hydrogen atoms fuse. 

What are the pros and cons?

The potential of fusion energy has thrilled researchers for decades. Just one glass of the fuel has the energy potential of 1mn gallons of oil and could generate, depending on the fusion approach, as much as 9mn kilowatt hours of electricity, enough to power a home for more than 800 years, scientists estimate.

Deuterium is widely available in seawater and tritium could be theoretically produced from the reaction. Moreover, unlike nuclear fission when atoms are split, fusion does not produce significant radioactive waste and could never result in a nuclear accident, such as the Chornobyl disaster in 1986.

However, in seven decades of experiments no group has developed a machine that could produce more energy than the power-hungry devices consume.

In 2022, US government scientists achieved a landmark breakthrough by producing more energy in a fusion reaction than the reaction consumes — a milestone called net energy gain or target gain. However the lasers used in that experiment still pulled far more energy from the grid than the reaction produced.

Will it save the planet?

Fusion’s advocates argue it is a technology that could genuinely save the planet. Fusion power plants could be placed anywhere in the world and once built the input costs to run the plants would theoretically be low.

Even if the private sector’s most ambitious plans are realised, fusion power plants would not be a widespread reality until at least the 2040s, meaning fusion energy would be unlikely to help significantly reduce emissions before 2050.

However, at that stage nuclear fusion could be used to meet the predicted huge increases in power demand because of the electrification of the global energy system and rising energy consumption in developing countries. Some scientists have suggested it could even be used to power energy-intensive carbon capture systems to begin to reverse some of the effects of climate change.

Has it arrived yet?

The race for fusion power is heating up but the nascent sector is still many years, if not decades away from connecting to the grid.

Fusion research was historically led by public sector scientists and the biggest fusion project in the world remains a publicly-funded international effort in France called Iter. But private sector fusion companies are now arguably making the fastest progress.

Among the most advanced is US-based Commonwealth Fusion Systems, which is building a demonstration plant in Massachusetts that it hopes to turn on in 2027. The company says it aims to supply electricity to the grid in the early 2030s.

Other fusion start-ups with projects under development include Sam Altman-backed Helion, UK-based Tokamak Energy, Canada’s General Fusion, Germany’s Proxima Fusion and European group Gauss Fusion.

Who is investing in it?

There are at least 53 fusion companies worldwide, according to the Fusion Industry Association, including 29 in the US, four in the UK, eight in the EU, three in China and three in Japan.

In total, those companies have raised almost $9bn in private investment to date and a further $795mn in public funding. Early investment came largely from billionaires such as Altman and Jeff Bezos, specialist venture capital groups and the investment arms of oil companies such as Eni and Chevron.

In more recent years, hedge funds, industrial groups and more generalist investors have also taken an interest. However, there are no publicly listed fusion companies and fusion executives say that billions of dollars more investment will be required to make fusion energy a reality.