British outfit First Light Fusion claims it has achieved nuclear fusion with an approach that could provide cheap, clean power.
Rather than rely on expensive lasers, complicated optical gear, and magnetic fields, as some fusion reactor designs do, First Light’s equipment instead shoots a tungsten projectile out of a gas-powered gun at a target dropped into a chamber.
We’re told that, in a fully working reactor, this high-speed projectile will hit the moving target, which contains a small deuterium fuel capsule that implodes in the impact. This rapid implosion causes the fuel’s atoms to fuse, which releases a pulse of energy.
This fusion energy can be absorbed by lithium flowing through the chamber, which runs through a heat exchange to boil water into steam that spins a turbine to turn a generator that produces electricity. The projectile would be fired every 30 seconds.
You can watch a visualization of this proposed reactor design below.
The goal is to use mostly readily available components to keep the system simple. To be clear, this power-generating reactor is pretty much at the blueprint stage. First Light says it has shown all of its workings and modelling to the UK Atomic Energy Authority, and demonstrated a successful fusion shot to the government watchdog. We’re told the regulator saw evidence that fusion was achieved during the test, from the neutrons emitted.
In this test shot, the projectile reached 6.5 km/s (14,540 mph) before hitting the target, we’re told.
This technology is experimental. The breakthrough being this design is simpler and “cheaper than traditional fusion approaches,” according to First Light. The biz next plans to demonstrate its system is capable of emitting more energy than is put into it, which will show its approach is viable for mass electricity production.
“Our approach to fusion is all about simplicity,” First Light’s co-founder and CEO Nick Hawker said in a statement this week. “Being simple, we believe projectile fusion is the fastest path to commercially viable power generation from fusion.”
Founded in 2011 and spun out of the University of Oxford, First Light focuses on projectile fusion, an idea proposed by physicists decades ago. It wasn’t thought to be a feasible technique at first because it required propelling projectiles to incredibly high velocities that are difficult and expensive to achieve. The novel design of First Light’s fuel target, though, may make it possible to produce significant amounts of fusion energy without accelerating the projectile to completely ludicrous speeds.
All about focus
The secret sauce lies in the complex geometry of the target, Hawker explained to The Register, which focuses the impact’s shockwave to collapse the fuel capsule, creating the extreme pressures needed to achieve nuclear fusion and release energy.
The deuterium-deuterium fusion reaction can produce a stable helium isotope and a neutron, or tritium and a proton. Tritium is also produced from the lithium when it’s bombarded with neutrons. The tritium can be consumed in a follow-up deuterium-tritium fusion reaction that emits another neutron and a helium isotope. With each fusion, energy is released.
Unlike the deuterium fuel, tritium is radioactive – it is a beta emitter – and is a byproduct First Light wants to keep to a minimum yet produce enough of it to aid the fusion reaction in the chamber.
“One of the biggest engineering challenges is to produce enough tritium so the reaction is self-sufficient,” Hawker told us. “Tritium is radioactive, and has a half life of over 12 years. It’s the biggest safety hazard, and we have to minimize levels to as low as 100 grams.”
In its experiment, First Light said it was able to produce 50 neutrons. Hawker said the amount of energy released was “very little,” and the company was working to increase the number of neutrons by 1,000 times in its next big run.
Before the technology can be used to power people’s homes, First Light’s equipment needs to achieve a fusion reaction capable of emitting a quintillion (1018) neutrons; at that point, a single projectile target collision could release enough energy to power the average UK home for more than two years, apparently.
Without the use of expensive lasers and magnets, First Light believes its technology will be comparable to renewables in terms of cost, and could reach under $50 per megawatt-hour.
It’ll be a while yet before that happens. First Light is working on building a pilot plant to scale up its technology in this decade. It hopes actual production plants will become operational in the 2030s, each capable of producing 150 megawatts of electricity, at a cost of less than $1bn a facility.
“With this result we have proven our new method for inertial fusion works and, more importantly, we have proven our design process,” Hawker added.
“The design used to achieve this result is already months out of date. As soon as we reach the maximum with one idea, we invent the next, and that incredible journey of discovery is what is so exciting.” ®