The news that scientists have made significant developments in fusion energy production, allows us to revisit the case for fusion and review the latest developments in the UK and internationally in this promising sector. Our nuclear specialist John Mathieson covers the details.

There’s a running joke in the energy community that commercial fusion power production is always at least 30 years away. It’s been like that for many decades, but given that recently scientists at the Joint European Torus (JET), located at Culham in Oxfordshire, managed to generate a record amount of power using fusion energy, how far away is this promising energy source from actually supplying electricity to the grid?

What is nuclear fusion?

Fusion is what makes the sun and all other stars shine, and it promises to offer inexhaustible amounts of energy because it uses hydrogen as a fuel. It works by bringing together the nuclei of hydrogen isotopes. Energy has to be put into the system for the nuclei to fuse, but the resultant energy generated is much greater. To keep the fusion reaction going, the hydrogen fuel has to be at a very high temperature – 150 million degrees Celsius in the case of JET – which creates a plasma which in turn is confined inside the tokamak using large electromagnets. (Tokamak is a Russian acronym meaning toroidal chamber with magnetic coils.) One of the major technical challenges of fusion is to get the heat to the outside of the device to produce electricity, without destroying the tokamak’s components.

How long has fusion been around?

Although the first fusion reaction on Earth was created in 1934, serious research did not occur until the 1950s, taking place in the USSR, USA, UK and Argentina. By the early 1960s it became apparent that a workable fusion generator was not to be had. However, later that decade, the Soviets produced good results from their T-3 tokamak reactor which led to many dozens of tokamaks being built around the world.

Within Europe, in the early 1970s, the Member States of the European Atomic Energy Community (Euratom) started to develop the JET concept and took the decision to build it at Culham. It was officially opened by Her Majesty Queen Elizabeth II in 1984.

After some modifications to its original design, JET achieved a world record of 21.7 megajoules of fusion power in 1997 using the deuterium and tritium isotope of hydrogen as the fuel. In 2010 a new beryllium/tungsten plasma facing wall was installed which was the forerunner of that which will be used in the next generation reactor, ITER. The recent record saw JET produce 59 megajoules of energy over five seconds (which made it the hottest place in our solar system during those five seconds). Although an important test result, this is not a huge amount of energy – its only enough to boil 60 kettles of water.

The next wave of fusion

The successor to JET is ITER, the International Thermonuclear Experimental Reactor project which began in 1988 and is being constructed in Cadarache in southern France; it is expected to be completed by 2025. It is a collaboration of 35 countries building the world’s largest tokamak. Again, ITER will be an experimental facility and will not lead to the building of fusion power plants. A further step called “DEMO” (DEMOnstration fusion power plant) will be required, building on the experience of ITER. But this will not be a single machine, designs are being developed in the EU and elsewhere in the world. Construction of the 500 MW European DEMO is not expected to start until the 2040s, which will certainly mean generation will not be until 2050 at the earliest.

What else is happening in the fusion energy sector?

There are many other initiatives to bring fusion power online sooner – and these are, now, achievable well within 30 years. For instance, the UK is also developing the Spherical Tokamak for Energy Production (STEP) which aims to produce greater than 100 MW of electricity by 2040. The site for this is expected to be announced by the government by the end of the year.

Another initiative aims to use Google’s vast computing power and expertise in machine learning, and a different configuration to the tokamak. TAE Technologies has raised £650m and predicts its reactors will be commercialised, producing net energy within 10 years. It has already achieved temperatures of more than 70 million degrees Celsius in its 30m long fusion cylinder called C2W “Norman”, after TAE’s founder, the late Norman Rostocker. A new prototype will operate at more than 100 million degrees Celsius. A spin-off company from the University of Oxford, First Light Fusion, uses inertial confinement fusion technology in which intense shock waves from its 22m long “Big Friendly Gun” crush gas-filled cavities producing high temperatures and compressions to achieve fusion. This system concept is also being developed at the National Ignition Facility in the US. Interestingly, neither of these are predicting when they think they can produce electricity on a commercial scale.

So, how far away are we from any of these initiatives achieving commercial scale fusion energy?

That’s still an open question, but less than 30 years does, now, appear to be on the cards!

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