Are we STEPping towards fusion energy?

Fusion has long been seen as a solution for clean energy and at a moment of spiralling energy costs and an urgency around net zero is back on the agenda. The UK has been exploring the development of fusion power for nearly 70 years and became one of the foremost locations for fusion energy research with the opening of the Joint European Torus, JET, at Culham, near Oxford in the early 1980’s. This facility has fired the imagination of many a young scientist and indeed fired JET into the record books with the most recent achievement being a sustained 10 MW output from the reactor for a period of five seconds.

The JET reactor is the precursor facility to International Thermonuclear Experimental Reactor, ITER, which is a project which will take the international fusion programme a step closer to energy production. The Director-General of ITER, Bernard Bigot, noted of the JET achievement that "A sustained pulse of deuterium-tritium fusion at this power level—nearly industrial scale—delivers a resounding confirmation to all of those involved in the global fusion quest".

In parallel, the UK has also developed its own design of a fusion reactor. The spherical Tokamak reactor called MAST (Mega Ampere Spherical Tokamak; this world is full of acronyms), which is the UK’s bet on being able to bring an energy generating reactor connected to the grid on an accelerated timescale of 2040. Tokamak reactors were originally conceived in Russia, and they use very powerful magnetic fields to hold what is called a plasma, or very hot gas, inside a vacuum. The plasma creates energy in a way that resembles the Sun by fusing two isotopes of hydrogen, deuterium and tritium. MAST is a smaller compact design than ITER and like many next generation devices will deploy superconducting magnets to create the high fields.

The STEP programme, acronym for Spherical Tokamak for Energy Production, is to accelerate the UK’s fusion reactor design towards commercial energy production with the site for this development being recently announced as the West Burton power station in Nottinghamshire in the Midlands. The site selected is a coal power station whose operation will cease shortly and the tag line for the campaign to bring it to the Midlands was “Fossil to Fusion”, recognising not only the transition of that site, but the heritage the region had in the energy sector. The Energy Research Accelerator partnership of Midlands universities have played an important role in attracting STEP to the region.

This is set to become an incredible platform for science, innovation, high value skills development and the creation of a technology cluster which will drive jobs and growth, but beyond all of that a key question is what are STEPs chances of producing sustained energy?

Though there have been great steps forward in terms of controlling the plasma and reaching the point where it is possible to get more energy out than is put into heating the plasma and generating nuclear fusion, there is still work to be done in moving from a scientific endeavour to a fusion power plant. This includes understanding how to extract energy in a sufficiently efficient manner that the overall power plant is energy net positive, it also includes how the tritium component of the fuel can be bred in a way which is sustainable. Tritium is planned to be manufactured via the neutrons produced in the fusion reaction interacting with a blanket of lithium around the reactor and then fed back into the plasma – a circular process. Finally, there is work to be done on developing materials that are sufficiently resilient, that they can withstand the harsh environment created in the fusion reactor.

The newly developed Accelerator Driven Neutron Irradiation Facility at the University of Birmingham is a national facility created as part of the National Nuclear User Facility, NNUF, programme which will allow scientists from the fusion community to test and validate materials to be used in the UK fusion programme. This facility will start operation in the coming months and will attract researchers from across the UK and indeed the globe.

The next 20 years is going to be a really key period in moving nuclear fusion from science, through engineering and then to the reality of energy production. There are going to be plenty of twists and turns in that journey, but the UK government has backed the sector to succeed – it needs not to disappoint.

Professor Martin Freer, Director of the Birmingham Energy Institute, University of Birmingham & Faye McAnulla, Programme Director at Energy Research Accelerator (ERA) hosted at University of Birmingham.