First Light Fusion has raised $25 million from existing and new investors. The funding round was led by Oxford Sciences Innovation (OSI) and includes IP Group plc and Hostplus.
The new funding will enable First Light to boost its science, engineering and simulation departments taking the total team to over 60. It will also use the new funding to accelerate planning for its prototype gain-scale experiment and further grid-scale reactor development.
The company also took the opportunity to complete a major upgrade of its pulsed power device, “Machine 3” designed to use electromagnetism to fire projectiles at around 20km/s into a “target” to create the conditions necessary to achieve fusion. The next step in the technological development will be to achieve ‘gain’, whereby the amount of energy created outstrips that used to spark the reaction. First Light says that it wants to demonstrate ‘gain’ this decade, and have a first-of-a-kind plant in the 2030s.
In 2019 Janet Wood talked to First Light chief executive Nicholas Hawker about the company’s very different approach to fusion power
Fusion researchers are always keen to talk through the fusion reaction. That’s not surprising: it requires them to create a plasma and compress it so much, at temperatures in the thousands of degrees, that it replcates conditons inside the sun. But I take it as read that it will work eventually.
My questions are much more prosaic. What is the fuel supply chain? Fusion reactors start with deuterium (heavy hydrogen, which can be abstracted from seawater) and tritium (effectively, even heavier hydrogen), which is rare. Tritium is generally produced from a nuclear reactor and decays fairly quickly to become unusable.
And my second question: when you have fusion under way, how do you convert it into electricity at competitive cost?
When I speak to First Light Fusion, unusually, we start with the second question. Chief executive Nicholas Hawker says: “You always have to keep in mind that you have to build the thing” and adds his response: “We are trying to keep the reactor as boring as possible.”
Chief operating officer Gianluca Pisanello puts it another way: there should be just one part of the project – the fusion process itself – that is not a very familiar and proven technology. The company has an innovative process for that, and one it hopes will clear significant hurdles this year. But “if you only focus on the science of doing fusion you will inevitably come up against engineering problems when you come to do the engineering. How do you scale up to a reactor? Every time we do anything, we have to do it with options that are in our current technology,” Pisanello says.
When I ask about the power generation process, Hawker does start with fusion. He notes that “80% of the energy in the fusion reaction comes in the form of highly energetic neutrons and it is these neutrons that have to be collected and turned into heat”.
First Light does that by catching the neutrons in liquid metal. At the centre, the fusion site is just a few millimetres across (see box) so “we have plenty of space”, says Hawker. Surrounding the fusion site – but at a metre or more distance – is a ‘curtain’ of liquid metal, which is heated as it absorbs the neutrons produced by the fusion.
“Imagine a cylindrical curtain of liquid metal around the reactor. It seems strange but actually liquid metal pool reactors already exist,” says Pisanello.
Sodium has been used in similar processes in the past, but the liquid metal in the waterfall will be lithium.
That answers my question about sourcing tritium; when neutrons hit lithium, a reaction creates tritium, which can be abstracted as the lithium is collected and returned to the top of the curtain.
Hawker says: “One of the first things we did was to make sure we could produce enough tritium. It can and it was relatively straightforward. Pure lithium and the natural isotope balance [works fine], so we can use the existing lithium supply chain and not enrich the lithium. That’s a big deal.” He explains that it is not so important for the first plant, but if you want a lot of plants having to add lithium ‘enrichment’ would make the supply chain much more expensive and challenging.
Heat exchangers transfer heat from the lithium. Eventually the heat is transferred to a very familiar steam circuit with a steam turbine. That could be direct, but the company has added a ‘molten salt’ circuit in between. This technology is similar to that used in concentrated solar power (CSP).
Having this ‘secondary’ loop makes heat transfer slightly less efficient, but it has two purposes, Hawker explains. First, it allows for flexibility.
First Light’s fusion process is not continuous; each pellet is hit and fusion occurs in a sequential process, like the explosions in an internal combustion engine. So, as with CSP, the molten salt acts as a thermal store.
But that also means the operator can decide to deplete the heat in order to run at higher power when the grid has a shortage (and power prices are high) and tap off less heat for generation when the power demand (and price) is low, also replenishing the heat store. “That’s important to the economics of the power plant,” says Hawker. In later versions of the power station the unit may serve heat customers as well.
Second, the molten salts are used to trap and remove stray tritium, which would otherwise create radiological contamination elsewhere, increasing costs like turbine maintenance and raising disposal issues (and costs) for the coolant water.
Nothing to see here
Overall, according to Hawker, a 300MW fusion power plant will sit on a footprint fairly similar to that of a similarly sized coal equivalent.
It will have hazards that have to be managed. The building does not have to contain a meltdown (unlike a nuclear fission reactor) but it would have to be ready for other hazards, like a lithium fire, and be able to contain the tritium in the event of disruption.
The plant would have a life of 30-40 years and its efficiency is not dissimilar to coal: a plant creating fusion in a pellet every five seconds would release 1,000MW of thermal energy. After all the plant’s fusion, heat transfer and steam-to-power energy ‘dues’ it would be exporting 300-350MW of electrical power.
That is the size of installation that is very familiar to planning authorities, construction firms, power grid managers and power traders – and is especially attractive to the latter if they can trade flexibility.
Hawker will not give me a price for power from the first reactor, but he is aiming for $60-70/MWh in later production. He does not expect to undercut low-cost wind and solar, but wants to compete against gas-fired plant and expects at least to be cheaper than fossil with carbon capture and storage.
He says there are plenty of ‘interesting’ options that could step up efficiency (and reduce prices), but that goes against his ‘boring’ philosophy. “The reason for a lot of the choices in the reactor design is to make the ‘first of a kind’ with minimal engineering risk and financial challenge,” he says. “We want to minimise the upfront cost. We are trying to design the ‘first of a kind’ so we can test all the engineering components within the next five years.”
One big target for First Light this year is to demonstrate that it will achieve its pulsed fusion. The other is to show that it can manufacture the necessary pellets. Previously it was expected that inertial confinement fusion would need extreme precision in pellet manufacture and equally extreme precision in hitting the target to achieve fusion. “The target is the key to the whole thing, it’s the hard bit and it’s where we have new technology,” says Hawker.
He says the company has developed a much better target that does not require ultraprecision. “We believe we have it and we can make it,” he says.
This year should show whether those two key barriers can be crossed. Meanwhile, the company hopes that the next five years will show investors that the remainder of the plant is familiar enough to make it investable. The approach is very different from that of other fusion initiatives. It remains to be seen whether investors find it boring enough to be interesting.
The fusion part
At the heart of a 300MW fusion power plant of this type, on a site not much different in size to an old coal-fired plant, will be a fusion site the size of a fingernail.
The company’s fusion process is far from the ‘torus’ approach used in other projects under way. Those international projects are trying to produce a cloud of plasma at the temperature of the sun and then wrangle it into the necessary configuration, using electric and magnetic fields, to force the fusion to occur.
First Light’s process is known to science as ‘inertial confinement fusion’. In it, the gas fuel is held in a cavity inside a solid ‘target’ around 10mm in diameter. The gas nucleii inside fuse when the target is hit with an intense shock wave. The pellet is destroyed (and the remains have to be abstracted from the liquid metal coolant) but the fusion has caused a burst of neutrons that carry an immense amount of heat. Every five seconds another pellet drops into place and the process is repeated.
The energy figures in fusion, like fission, are huge. Inertial confinement fusion in just three tiny 10mm pellets emits enough energy for a typical house for a year. In practice, the energy needs of the fusion process, and inefficiency in converting heat to power, takes up two thirds of the available energy. But that would still mean power production for a domestic property for a year is achieved in comfortably under a minute.