What is nuclear fusion? The science – and the latest news on it – explained

This article was originally published in 2017 and most recently updated on 19 May 2023.

• At Davos in January, the lead US government scientist behind a nuclear fusion breakthrough called for more public investment to scale the technology.Now Microsoft has signed a deal with private US nuclear fusion company Helion to provide the tech firm with electricity in five years.Nuclear fusion is what happens in the Sun and other stars and involves joining two atomic nuclei to make one larger one.Fusion power offers the prospect of an almost inexhaustible energy source for future generations.

“If we want to take this forward, public-private partnerships are going to be essential.” These were the words of nuclear scientist and Director of the US Lawrence Livermore National Laboratory, Kim Budil, back in January 2023 at Davos a month after her team had made a crucial breakthrough in nuclear fusion – achieving a “net energy gain” in a step towards a cleaner energy future.Private sector investment in the nascent technology has surged in the past 20 years, according to McKinsey, and now Microsoft has announced it has made a deal with private US nuclear fusion company Helion for power in 2028.Microsoft President Brad Smith said Helion’s work “supports our own long-term clean energy goals and will advance the market to establish a new, efficient method for bringing more clean energy to the grid, faster”.

Helion has raised more than $570 million in private capital, including $375 million from OpenAI CEO Sam Altman in 2021, but the details of the Microsoft deal have not been disclosed.The nuclear fusion company’s seventh-generation machine is set to come online next year and demonstrate electricity generation, using pulsed high-power magnet technologies to achieve fusion. In 2021, it was the first private company to achieve 100 million degrees Celsius (180 million degrees Fahrenheit), half the temperature needed to achieve fusion.

The nuclear fusion race

Government labs and more than 30 companies are racing to generate power from fusion –including Budil’s team in California.In December 2022, they managed to produce more energy from the reaction than it consumed – a net gain of 1.5 megajoules in less time than it takes light to travel one inch.”Monday 5 December was an important day for science,” said Under Secretary for Nuclear Security and National Nuclear Security Administration (NNSA) Administrator Jill Hruby.At the World Economic Forum’s Annual Meeting in Davos, Budil explained the experiment involved beaming 192 lasers on a tiny target and heating it to create a self-sustaining reaction

“If I look at the private-sector fusion companies that have already been spun out, they have needs for expertise and certain specific skills that it would be cost prohibitive to develop within a start-up framework. So they can partner with the laboratories to get access to that capability and expertise.”To advance the cause of fusion, we have to create an ecosystem where any private sector players in this area who want to commercialize the technology can work with us to help advance the target designs – think about laser architectures or other driver architectures –to benefit from our expertise and what will be required to operate a facility at this scale.”I’m hopeful we will start seeing significant public sector investments in the energy application of this technology. We already have several companies formed around inertial confinement fusion that are starting to explore partnerships with us on how to take the technology forward.”For the next few years, it’s essential to work together.”

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What’s the World Economic Forum doing about the transition to clean energy?

Moving to clean energy is key to combating climate change, yet in the past five years, the energy transition has stagnated. Energy consumption and production contribute to two-thirds of global emissions, and 81% of the global energy system is still based on fossil fuels, the same percentage as 30 years ago. Plus, improvements in the energy intensity of the global economy (the amount of energy used per unit of economic activity) are slowing. In 2018 energy intensity improved by 1.2%, the slowest rate since 2010. Effective policies, private-sector action and public-private cooperation are needed to create a more inclusive, sustainable, affordable and secure global energy system. Benchmarking progress is essential to a successful transition. The World Economic Forum’s Energy Transition Index, which ranks 115 economies on how well they balance energy security and access with environmental sustainability and affordability, shows that the biggest challenge facing energy transition is the lack of readiness among the world’s largest emitters, including US, China, India and Russia. The 10 countries that score the highest in terms of readiness account for only 2.6% of global annual emissions.

To future-proof the global energy system, the Forum’s Shaping the Future of Energy and Materials Platform is working on initiatives including, Systemic Efficiency, Innovation and Clean Energy and the Global Battery Alliance to encourage and enable innovative energy investments, technologies and solutions.Additionally, the Mission Possible Platform (MPP) is working to assemble public and private partners to further the industry transition to set heavy industry and mobility sectors on the pathway towards net-zero emissions. MPP is an initiative created by the World Economic Forum and the Energy Transitions Commission. Is your organisation interested in working with the World Economic Forum? Find out more here.

What is nuclear fusion exactly?

Our current nuclear power stations use nuclear fission – essentially splitting an atom’s nucleus.Nuclear fusion is what happens in the Sun and other stars and involves joining two atomic nuclei to make one larger one. Both reactions release large amounts of energy, but with nuclear fusion, there is very high energy yield and very low nuclear waste production. Fusion occurs when two light atoms bond together, or fuse, to make a heavier one. The total mass of the new atom is less than that of the two that formed it; the “missing” mass is given off as energy, as described by Albert Einstein’s famous E=mc2 equation.

The most promising combination for power on Earth today is the fusion of a deuterium atom with a tritium one. The process, which requires temperatures of approximately 72 million degrees Fahrenheit (39 million degrees Celsius), produces 17.6 million electron volts of energy.Deuterium is a promising ingredient because it is an isotope of hydrogen. In turn, hydrogen is a key part of water. A gallon of seawater (3.8 litres) could produce as much energy as 300 gallons (1,136 litres) of petrol.

Challenges for nuclear fusion researchers

While nuclear fusion power offers the prospect of an almost inexhaustible energy source for future generations, it has also presented many so-far-insurmountable scientific and engineering challenges.In the Sun, massive gravitational forces create the right conditions for nuclear fusion in the star’s core, but on Earth they are much harder to achieve.Fusion fuel – different isotopes of hydrogen – must be heated to extreme temperatures of around 50 million degrees Celsius, kept stable under intense pressure, and