This week the media celebrated a ‘breakthrough’ in nuclear fusion. Following a record-breaking reaction, several are claiming that the ‘ignition’ threshold – required for a self-sustaining reaction – had been achieved. Stripped back, however, it is obvious that commercially viable fusion is still far from reality. It must not distract financial attention from renewable energy deployment.
Rethink Energy first wrote about this reaction after the experiment was conducted in August 2021 at the Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) in California. The year that researchers have spent analyzing the reaction have confirmed the expected results. Results have been published in Physical Review Letters, with two in Physical Review E.
A single 20 nanosecond shot from a laser sparked a fusion explosion that produced 1.35 megajoules of energy – around the amount of energy required to drive an electric vehicle one mile or to boil a kettle. While this might sound small, the energy produced was eight times greater than ever achieved from the facility and was about 5 times the energy physically absorbed by the capsule.
“The record shot was a major scientific advance in fusion research, which establishes that fusion ignition in the lab is possible at NIF,” said Omar Hurricane, chief scientist for LLNL’s inertial confinement fusion program. “Achieving the conditions needed for ignition has been a long-standing goal for all inertial confinement fusion research and opens access to a new experimental regime where alpha-particle self-heating outstrips all the cooling mechanisms in the fusion plasma.”
In one of the publications, the team argues that “ignition is a state where the fusion plasma can begin ‘burn propagation’ into surrounding cold fuel, enabling the possibility of high energy gain.” This means that the energy output from the hydrogen is greater than the energy it receives.
But the energy out versus energy absorbed is not how ignition should be defined from a commercial perspective. The energy output represents just 70% of the total energy input from the laser pulse that triggered it, with much of that energy being lost “en route.”
The NIF uses a fusion technology referred to as inertial confinement. It combines tiny blasts from 192 high power laser beams to heat and compress hydrogen isotopes until they undergo fusion and release a huge amount of energy. Once the energy used to power these lasers is less than the energy produced by the reaction, fusion represents a vast source of clean energy.
Just 1 kilogram of fusion fuel can power 10,000 homes for one year and replace 55,000 barrels of oil, 6 million kilograms of natural gas, or 10 million kilograms of coal, with zero CO2 emissions, according to Canadian start-up General Fusion.
The NIF achievement represents a huge step. After decades sitting at the 3%-of-ignition level, a jump to 70% would appear to point to commercial fusion being just around the corner.
However, attempts to repeat the reaction and achieve the same level of fusion yield, have so far been unsuccessful, with most yielding between 400 kilojoules and 700 kilojoules. Big steps in nuclear fusion are also few and far between. A record reaction at the JET facility in Oxford, UK, last year broke a record that had been held since 1997.
Achieving commercial fusion off the back of the NIF’s success could represent decades of future work. Technical barriers remain to operate and control a system at over 100 million degrees Celsius, before cost even becomes a consideration.
The reaction also needs to be sustained. Using NIF’s approach, if fusion blasts could be maintained at a rate of 10 reactions per second, a power plant could harvest energy from the high-speed neutrons produced to generate electricity.
Despite huge amounts of investment into international collaboration projects like the $25 billion International Thermonuclear Experimental Reactor (ITER), no one has yet reached the ignition point for nuclear fusion. Even at ITER’s tokamak reactor, researchers don’t expect to hit the benchmark for another 10 years using its magnetic confinement fusion, although several private companies are starting to talk up their prospects. TAE Technologies, General Fusion, Commonwealth Fusion Systems, First Light Fusion, Tokamak Energy, and Zap Energy are among those trying to drum up enthusiasm with investors with near-term demonstrator projects.
The National Ignition Facility cost $3.5 billion, more than $2 billion more than expected, and is behind schedule, with researchers initially targeting 2012 as the deadline to prove ignition was possible using the design.
From our own point of view, we do not welcome too much enthusiasm for this technology too early – it would be the perfect opportunity for fossil fuel interests to say “Let’s wait for Fusion to arrive,” at the expense of renewables. By 2050, it is essential that the world reaches net zero emissions, and fusion technologies – even in an optimistic scenario – will still be at commercial infancy.