Spherical tokamak aims for operation in 2030

2 February 2017

David Kingham, CEO of UK based Tokamak Energy says experimental and theoretical research has shown 'spherical' tokamaks to be a "fast route to fusion" compared with more "conventional" tokamak devices such as Joint European Torus (JET). He was addressing a 25 January International Energy Agency (IEA) meeting on fusion power. Tokamak Energy was invited to the meeting as "one of the three most promising fusion concepts", along with General Fusion and Tri-Alpha Energy.

Tokamak Energy's technology is based on high temperature superconducting (HTS) magnets, which allow for relatively low-power and small-size devices, but with high performance. The world's first tokamak using exclusively HTS magnets - the ST25 HTS – was Tokamak Energy's second reactor. It demonstrated 29 hours continuous plasma during the Royal Society Summer Science Exhibition in London in 2015, achieving a world record.

The next reactor under construction at Tokamak Energy's facility at Milton Park in Oxfordshire is the ST40 and is expected to produce plasma temperatures of 15m degrees Celsius. "The ST40 is designed to achieve 100m degrees C and get within a factor of ten of energy break-even conditions. To get even closer to break-even point, the plasma density, temperature and confinement time then need to be fine-tuned," Kingham said. "The next step is to build a reactor that takes this knowledge and uses it to demonstrate first electricity from fusion by 2025. This will then form the basis of a power plant module that will deliver electricity into the grid by 2030."

Tokamak Energy has raised private investment of GBP20m ($25m) from Oxford Instruments, L&G Capital, the Institution of Mechanical Engineers, the Rainbow Seed Fund and others. It has a "valuable dialogue", Kingham said, with Princeton Plasma Physics Laboratory on spherical tokamaks, and with the Plasma Science and Fusion Centre at MIT on HTS magnets. Both institutions are "leading laboratories that share our vision", he noted. The most recent and largest investment into Tokamak Energy late last year was GBP10m from Legal & General Capital, British billionaire David Harding and other private individuals. This brought the total investment Tokamak Energy has received to almost GBP20m. 

In an interview with World Nuclear News (WNN) on 26 January, Kingham said the ST40 is due to be completed and start commissioning this Spring. Tokamak Energy is "unique among nimble, privately funded fusion energy ventures", he said, in the way that the majority of them are looking for alternative and quicker routes to fusion energy, in comparison to large publicly funded companies, which often make slow progress but do sometimes produce new scientific breakthroughs. Tokamak Energy is unique amongst privately funded fusion energy ventures, he added, as it is aiming to accelerate the development of fusion energy based on the tokamak.

Other "routes to fusion" are being taken by, for example, General Fusion and Tri-Alpha Energy, he noted. General Fusion is taking the approach of Magnetised Target Fusion, with the aid of modern electronics, materials, and advances in plasma physics. Tri-Alpha Energy is utilising proprietary advanced beam-driven field reversed configuration technology to create a superheated plasma environment. Tri Alpha Energy has operated a national lab-scale machine, which in many aspects resembles a future power plant, in which hydrogen and boron would fuse generating helium and energy.

More than 200 tokamaks have been built in laboratories worldwide as well as the €20bn ($21bn) international agreement to build Iter in France. Iter is currently scheduled to produce its first plasma in 2025 and start deuterium-tritium operations in 2035. However, it will not demonstrate the use of nuclear fusion to produce electricity. That will be the task of the Demonstration Fusion Power Reactor, or DEMO, which will aim to demonstrate the continuous output of energy, supplying electricity to the grid. According to EUROfusion, DEMO is expected to follow Iter by 2050.

"Fusion projects in government laboratories have become increasingly expensive and slow,” Kingham said. “For example, Iter is now planning to start full power operations in 2035. However, now there is a new way forward with fusion, based on rapid development of new technologies by private ventures. Being a privately funded commercial entity with the necessary expertise and team, we feel that we can make fusion a reality and have stated a clear timeline to do so, i.e. putting fusion electricity into the grid by 2030," he said.

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