Poster session SIMposium 2023

When will nuclear fusion keep the lights on?

This year’s Master’s SIMposium, Economically Competitive Fusion Energy, aimed to find out when nuclear fusion will generate electricity power at a price people can afford.  Held at the Hall on 3 April, the event attracted a full audience to hear presentations from senior figures from the fusion industry, from the City’s financial sector, and from researchers tackling the difficult technical challenges that still remain.  Oral presentations in the morning were followed by posters in the afternoon.

It fell to me, as Master of the Worshipful Company of Scientific Instrument Makers, to welcome both my own Liverymen and also the many guests of the Livery, who included masters, deputy masters and members of other livery companies, as well as those with a general interest in fusion’s progress.  The SIMposium had the support of the Lord Mayor, Nicholas Lyons, and the Senior Alderman Below The Aldermanic Chair, Michael Mainelli.  Last year’s Sheriff, Alderman Alison Gowman, who chairs the Livery Climate Action Group, attended the afternoon session.


I offered the opinion that energy was, after many years absence, now back in the spotlight as a result of Russia’s invasion of Ukraine, which had exposed Europe’s over-reliance on Russian gas, Germany’s in particular.  A re-evaluation of nuclear power was underway, with Britain building a dual-reactor power station at Hinkley Point C, with a similar installation planned for Sizewell C.  Those plants were based on nuclear fission, by which energy was released through “splitting the atom”.  But what about its cousin, nuclear fusion, where squashing together small atoms to form bigger ones released even greater amounts of energy?  Often touted as the Holy Grail of sustainable, low carbon energy production, fusion had the potential to provide an almost limitless source of clean, safe electrical power.  But when would this happen, and what financial strategies would be needed?


Liveryman Tom Davis of Oxford Sigma framed his answer in terms of the global fusion landscape.  He looked at the physics first, and explained that the huge gravitational field generated by the sun’s great mass enabled nuclear fusion to occur there, but that, on earth, enormous magnetic or inertial forces were needed, instead, to keep the hot, dense plasma together long enough to react.  Tokamaks used superconductors to generate the necessary magnetic fields, while the forces needed for inertial containment were induced either by focusing a bank of lasers on a fuel pellet containing deuterium and tritium, or else by firing a hypersonic projectile at the pellet.  The resulting implosion caused the fusion reaction and the release of energy, mainly in the form of highly energetic neutrons.


A fusion reactor could be designed in a multitude of ways, and a matching number of private companies had now sprung up to exploit the opportunities: 21 in the USA, three in the UK, two in Japan, and one in both Germany and France by the middle of 2022, with several more coming into existence in the last few months.  Fusion investment had been encouraged by the bipartisan political support found in the USA.  But Britain was now also an attractive place to invest, especially after the government chose the HSE over the ONR as fusion’s regulator, which improved regulatory certainty.  UK companies had, in fact, attracted their fair share of the five billion dollars in private money that had now been invested in fusion across the world.  He expected fusion-based electrical power to be generated in the 2040s.


Tim Bestwick, who is the UK Atomic Energy Authority’s Chief Technology Officer,

surprised his audience at the outset with the “fun fact” that the power density of the fusion reactions in the sun was no more than you would find in the average garden compost heap, because of the slowness of the proton-proton fusion taking place there – the “burning” of ordinary hydrogen, a process that could be sustained only in a massive star.  Fusion on earth meant fusing together the rarer hydrogen isotopes, normally deuterium and tritium, to release energy as helium was formed.  The operating temperatures would be ten times hotter than the sun, which was obviously a challenge.  But technical progress was spurred by the pressing need, now universally recognised, for environmentally friendly sources of power.  The UKAEA’s strategy was to facilitate collaboration in key areas where progress was required, such as high performance plasmas, tritium breeding and tokamak optimisation.  Success in these would act as stepping stones on the route to the design of an integrated power plant.


The successful experiments in the Joint European Torus (JET), based at Culham, would come to an end at the end of 2023, but the UK was investing in the next stage of fusion development.  The Spherical Tokamak for Electricity Production (STEP) was a prototype fusion power plant that would be built (in a sign of the times) on the site of West Burton A, a coal-fired power station in Nottinghamshire that was finally turned off in the week before the SIMposium.  While not committing to a firm date, Dr Bestwick was confident that fusion would be a major component of the electricity supply industry in the second half of the century.


Douglas Hansen-Luke, Executive Chairman of Future Planet Capital, provided insights from an investor’s viewpoint.  Governments across the world and the UN accepted the need to support and expand sustainable energy, and Britain was one of the world leaders in fusion technology and employed high quality scientists and engineers on the task of taking it further.  There were excellent, long-term returns in prospect.  The five billion US dollars of private money so far invested in fusion development worldwide looked minute in comparison with the enormous and growing size of the market in energy.  Moreover, private fusion investment up to now was a tiny fraction of the 333 bn USD of venture capital invested globally during just one year, in 2021.


Investors would be attracted, he suggested, to investable fusion projects, where the returns could be predicted with a high degree of confidence.  One facet, regulatory certainty had clearly been improved by the Government’s selection of the HSE as the fusion regulator.  It needed to be remembered, too, that different classes of investor would have different criteria for what was an acceptable investment timescale.  The sovereign wealth funds, such as those held by Norway, Abu Dhabi and Singapore, had the longest time horizons because they were set up to help their country’s citizens into future generations.  Insurance companies and pension funds were again long-term investors, but they would expect a good return within thirty years.  For venture capitalists, the time horizon was typically ten years, and the exit strategy for them would be a listing on the stock exchange.  He estimated that, worldwide, there were probably two fusion companies that merited a 2 to 5 bn USD valuation, while more fusion companies might be valued in the  range of 1 to 2 bn USD, and others at between 100 to 500 M USD.


Governments also had a role to play in a new and important technology like sustainable fusion.  The UK’s present model involved a core of government money, which went into sponsorship of important R&D and also provided catalytic funds to match private investment.  It was right that the government was providing a fusion platform, and it was essential that it did not change its mind about long term support.  It needed to bear in mind the scale of the returns expected, which would be extremely large.


David Kingham, of Tokamak Energy, said that his company, based in Oxfordshire, employed 250 scientists and engineers to develop and build successively more powerful fusion machines.  They saw high performance in smaller, spherical (as opposed to doughnut shaped) tokamaks as the key to the commercial success of fusion.  Their ST40, which had a principal radius of only 40 cm, reached a plasma temperature of 100 degrees Celsius last year, which was above the threshold needed for commercial power generation.  The triple product (density x temperature x confinement time), achieved at the same time, was then the highest of any private concern.


The principal challenges lay in plasma engineering, materials and magnetic systems, but the use of superconducting magnets, operating at the relatively high temperature of 20 degrees above absolute zero, were allowing designs to be scaled up, while, at the same time, the company was growing its operational experience on the way. A new, beefed up version of the ST40 spherical tokamak, called the ST80-HTS, would employ high temperature superconductors and would begin operations in 2026.  The lessons learned would then be incorporated in Tokamak Energy’s fusion pilot plant, the ST-E1, which would demonstrate up to 200 MW of net electrical power.  This was scheduled to begin operation in 2035.  The ultimate aim was to produce electricity at a cost of 50 USD per MWh.


Lyn McWilliam and Adomas Lukensa of UKAEA rounded off the morning session with a two-hander, in which they examined open challenges for measurement in fusion.  The temperature range over which on-line measurements were needed was vast: from 14 degrees above absolute zero, for the solid hydrogen isotope fuel pellets, up to 500 degrees Celsius, which was the temperature envisaged in the European Union’s proposed demonstration fusion power plant, DEMO, for its molten lithium-lead primary coolant.  Some of the lithium would, after bombardment by the neutrons generated during fusion, produce tritium, and this would be harvested for fuel.  Rapid, on-line measurements of tritium, both concentration and isotopic content, would be essential.


Good control of the interface to the power plant would require dynamic measurements of the pressure profile and the mass flow rate of the molten lithium lead, as well as of the distributions of flow velocity and liquid metal temperature.  Moreover, temperatures seen at different parts of the containing structure needed to be measured and controlled to minimise thermal stress.


The molten lithium lead would transfer its heat to a pressurised water circuit, which was expected to run at similar conditions to those found in a pressurised water reactor (PWR), that is to say 300 degrees Celsius and about 150 bars.  Any incipient break in the barrier between the liquid metal and the cooling water needed to be detected quickly to prevent damage from the exothermic reaction that could result.


Providing all the necessary process measurements fast enough constituted a significant challenge.  The presenters said that they would welcome any thoughts that Scientific Instrument Makers might have on the problems they had set out.


The poster sessions viewed after lunch were well attended, and provided further evidence of the high level of scientific effort being devoted to finding solutions to the technical questions that still needed answering.


Hugo Doyle, who is Head of Experimental Physics at First Light Fusion, explained in his poster that his private sector organisation was developing projectile fusion, a new approach to inertial fusion that he claimed was simpler, more energy efficient, and had lower physics risk.  The method used a pulsed process, where a small amount of fuel was injected and sparked to make it burn, as in an internal combustion engine. But, while others used a large laser as the “spark plug” to trigger the reaction, First Light Fusion used a high velocity projectile instead.  The key lay in the design of the target, which was composed of a fuel capsule embedded in a mechanical amplifier.  The amplifier raised the impact pressure of the projectile and, at the same time, caused the shock wave to surround the fuel pellet and converge on it from many directions.  First Light Fusion, which was spun out from the University of Oxford in 2011, now employs over a hundred people and is working towards a power plant producing 150 MW of electricity, firing once every 30 seconds, and costing less than $1 bn.


So what did we learn from the SIMposium?  Clearly a plethora of different technical solutions are being tried, to resolve the fundamental challenges of fusion.  Some of these, at least, seemed to have passed the proof-of-concept stage and are now being scaled up.  This would explain the significant financial investment they are attracting.


The key to further financial backing will be to frame the case in terms of investable projects, with a timescale appropriate to the potential investor.  According to one presenter, fusion may generate its first electrical power in 2035, which is only 12 years away, making venture capital funding just about possible.  Others thought that electrical power would not be produced until after 2040, and that fusion would not make a substantial contribution to electricity production until the second half of the century.  These longer timescales might, however, still be attractive to insurance companies or sovereign wealth funds.  After all, get it right and the returns could be huge!


Philip Thomas