Don’t get too excited, no one has cracked nuclear fusion yet

Aerospace giant Lockheed Martin’s announcement this week that it could make small-scale nuclear fusion power a reality in the next decade has understandably generated excitement in the media. Physicists, however, aren’t getting their hopes up just yet.

I recently returned from the International Atomic Energy Agency’s Fusion Energy Conference in St Petersburg, Russia, the world’s leading conference on the development of fusion power. There was no announcement of research by Lockheed Martin, and the company did not field any scientists to report on their claims.

Lockheed Martin claims that its technology development offshoot, Skunk Works, is working on a new compact fusion reactor that can be developed and deployed in as little as ten years. The only technical details it provided are that it is a “high beta” device (meaning that it produces a high plasma pressure for a relatively weak magnetic field pressure), and that it is sufficiently small to be able to power flight and vehicles.

This isn’t enough information to substantiate a credible program of research into the development of fusion power, or a credible claim for the delivery of a revolutionary power source in the next decade.

Fusion power

Nuclear fusion, co-discovered by the Australian physicist Sir Mark Oliphant, is the process that powers the sun and stars. If harnessed, it offers the possibility of virtually limitless clean energy. As its name implies, fusion energy is released by joining light atomic nuclei (typically deuterium and tritium, which are isotopes of hydrogen) within a high-pressure, extremely high-temperature “plasma” contained by magnetic fields.

The attraction of fusion is substantial. Like nuclear fission, the fusion process produces zero greenhouse gases. Unlike fission, which generates radioactive waste as a by-product, fusion is intrinsically clean. The deuterium-tritium reaction produces helium and energetic neutrons – the only waste is generated indirectly, when the neutrons hit the shield of the reactor.

Based on existing technology, fusion power plants could be recycled in 100 years. Research into the use of advanced alloys and ceramics suggests that this period could be made even shorter.

Deuterium, a fuel for fusion, is naturally abundant in water. Any country with access to water automatically has access to deuterium, thereby dramatically reducing geopolitical tensions over energy security. Per kilogram of fuel, fusion releases four times more energy than fission, and a staggering 10 million times more than coal.

World deposits of deuterium are enough to power civilization for millions of years. Access to fuel supply will therefore no longer be an issue, economically or politically.

More importantly, the fusion reaction is inherently safe. Turn off the heating power and the reaction stops. There can be no nuclear chain reactions, no reactor meltdowns, and no explosions.

Contain your excitement

While the rewards of fusion power are substantial, so are the challenges of making it a reality. The deuterium-tritium reaction is the easiest fusion reaction to initiate, yet the optimal temperature needed is 100 million degrees C, which is six to seven times hotter than the core of the Sun.

The key to producing significant fusion power is confining the plasma long enough at a high enough temperature and density for there to be a net power gain.

The international research community is currently working on a new experimental fusion reactor, called ITER, which will have a field strength of about 5 Tesla and a radius of 6 m. Overall, the ITER device is 60 m tall, weighs 23,000 tonnes, and has 80,000 km of niobium tin superconducting strands. Such a device does not fit on the back of a truck.

Despite the difficulties, progress in fusion power has exceeded the spectacular improvement in computer power. In the space of 30 years, power output has increased by a factor of more than a million. Present-day experiments have a power output of tens of megawatts. ITER will produce 500 megawatts of fusion power.

Lockheed Martin will need to show a lot more research evidence that it can do better than multinational collaborative projects like ITER. So far, its lack of willingness to engage with the scientific community suggests that it may be more interested in media attention than scientific development.

Matthew Hole is Australia’s representative on the IAEA International Fusion Research Council and Chair of the Australian ITER Forum, a consortium of scientists and engineers who support an Australian participation in ITER.

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