Interview: Jonathan Carling, Tokamak Energy’s new CEO

The Engineer By Stuart Nathan 22nd February 2018

Tokamak Energy’s new CEO plans on using his commercial nous to get fusion-generated electricity on the National Grid by 2030

Energy generation by nuclear fusion is one of society’s biggest technological challenges. Decades after fusion was first demonstrated, there has been no obvious breakthrough on this front, though it’s frequently claimed that one is just around the corner. Now, following visible progress at the International Thermonuclear Experimental Reactor (ITER) in southern France, it seems that the long-anticipated milestone might finally be reached.

Yet away from this vast building site, a UK company is making the audacious claim that it will beat the international consortium to the punch. Tokamak Energy – based at Culham in Oxfordshire, next to ITER’s forerunner, the Joint European Torus (JET) – aims to supply fusion-generated electricity to the National Grid by 2030, before ITER has even started fusion reactions. Chief executive Jonathan Carling, who has no background in high-energy physics, comes instead from the far more commercial aerospace and automotive industries.

Carling, who trained as a mechanical engineer at City, University of London in the mid-1980s, took on the CEO role last November, replacing co-founder David Kingham. Prior to that, he was Rolls-Royce’s chief operating officer for civil large engines. “At Rolls-Royce, I looked after the manufacture of the Trent family of engines and the overhaul network, looking after the project teams that develop the engines and are responsible for building, selling and servicing them,” he told The Engineer.

“[Before that,] I also held a number of chief engineer roles at Jaguar Land Rover; I was chief engineer for powertrain systems, and also on the Jaguar X-Type. I was chief programme engineer for the Jaguar XF.”

His curiosity about nuclear fusion did not take on a professional dimension until his first encounter with Tokamak Energy, however. “I’ve been interested in nuclear fusion, as anyone who’s an engineer or a technical person would be, but until I discovered Tokamak Energy, like many people I think I thought of it as something governments were pouring billions into, only to periodically tell us that it was a few more decades off.

“When I found that Tokamak Energy was creating a way for a small, modular fusion reactor, I was immediately attracted. Here’s an agile private firm who’s building on existing science – and having worked as COO in a couple of businesses, I like to see data and executability – and thought, ‘This looks like a fantastic challenge,’ especially as the business is currently in a phase where it’s moving from providing the scientific basic platform to doing the engineering and creating the actual machines, which is my background.”

What distinguishes Tokamak Energy from the ITER project is the shape of its planned fusion reactor. Both ventures are looking at magnetic confinement fusion, whereby a plasma of hydrogen nuclei is confined within a strong magnetic field and heated up, forcing the nuclei to fuse together and release energy. But unlike ITER’s reaction vessel – a huge, flat torus, called a tokamak after the original 1950s Russian technology – the kind of machine Tokamak Energy is investigating uses a plasma confinement vessel shaped more like a cored apple. Advocates of these so-called spherical tokamaks argue that they are more stable and easier to control than their wider, flatter cousins, as well as being cheaper to build.

Tokamak Energy believes that a spherical tokamak much smaller than its ITER counterpart will be able to provide enough heat from the fusion reactor to generate electricity economically. The key to this, says Carling, is the strength of the magnetic fields keeping the plasma in place. “If you look at fusion power in tokamaks, the energy is proportional to the plasma volume, but it also varies according to the fourth power of the magnetic flux – so if you can run with very high magnetic flux, then that will have a much bigger effect on the fusion power than making the machine bigger.”

Spherical tokamaks are said to be more stable than the wider, flatter type

This is just one of the insights he has gained since starting his new job. “It’s a very fast learning curve but luckily I’ve got some true experts – the best people in the world in this field – all around me and they’ve been incredibly welcoming. I’ve asked them for information about the business and the physics and they’ve given me lots to digest.”

Meanwhile, he isn’t too concerned about his status as a particle physics layman. “As a leader, it’s important to remember that I don’t need to reach a level of expertise equal to the chief scientist,” he says. “You need to understand the overall mission and what the team needs from their leadership to succeed.” Another strength, he believes, is his expertise in running businesses and raising funding. “I’ve worked with funding businesses but not in a pre-revenue business. Pitching for investment or funding businesses isn’t new to me but in this stage, it is. I’ve been pitching the business, which involves telling people how it works, so I need to understand how the machines work well enough to do that.”

Two factors will enable Tokamak Energy to reach its goal quickly, he says. One is the smaller scale of the machines, compared to ITER’s. The other, crucially, is private sector funding. To date, the company has raised more than £22m from a variety of sources, including venture capitalists and more mainstream institutional investors such as pension funds, Carling says. It is about to embark on a new funding round, having completed its fourth fusion reactor, known as ST40, last year.

One explanation for Tokamak Energy’s ambitious schedule is that Carling believes the major roadblocks to fusion power have been removed. “We’re about to run a big test to reach 15 million degrees Celsius in ST40, and later this year we hope to reach 100 million, which is fusion temperature. That will get us very close to energy break-even in this machine by 2022, and that will prove all the basic science and engineering.” The company will then embark on its next construction project, the ST200, which will be three to four times larger than its predecessor (the ST40 is 4m height and 2.5m in diameter). Moreover, the ST200 will be equipped with a key technology: high-temperature superconductors based on REBCO (rare earth barium copper oxide).

REBCO magnets are more compact than other superconductors and, most importantly, work at temperatures just below 77 Kelvin (-196C), achievable with liquid nitrogen. By contrast, ITER’s niobium-tin and niobium-titanium magnets need liquid helium at a few Kelvin above absolute zero – a much more costly demand, requiring larger equipment.

Tokamak Energy first used REBCO magnets on ST40’s predecessor, which for ease of construction uses copper in its magnets. But, Carling stresses, they are a relatively new technology and the company must develop both the magnets and the supply chain to build them. With this in mind, it has formed a partnership with Atkins.

“We hope to have ST200 running with net energy gain and industrial-level heat production in 2025,” he says. “That gets us to electricity on the grid by 2030.”