Harnessing fusion energy as a source for carbon-free, near limitless electricity seemed much closer last November when the Department of Energy breathlessly announced a key advance: there was a successful “controlled burn” of the fuel in an experimental fusion reactor at the National Ignition Facility at Lawrence Livermore National Lab. This means that more energy was produced as the fuel burned than it took to ignite the fuel using lasers.
The news was flashed around the world, leaving the impression that a fusion power generator is finally at hand, marking the dawn of a new era.
Fusion, not to be confused with fission, is the atomic reaction that powers the sun and our big thermonuclear bombs. Taming the fusion reaction as a reliable source of electricity has been a goal for more than 60 years.
This does represent an important advance and I am relieved, since the team at Livermore has been working toward this goal for more than 10 years under the guise of a program called “Stockpile Stewardship,” which studies whether our stash of aging fusion-powered bombs will go off if we ever need them to.
After the announcement, several sources looked at the energy budget of the experiment, and the future isn’t here quite yet.
While it is true the energy released exceeded the energy delivered by the lasers that ignited the tiny fuel pellet, the electricity needed to run the lasers was overlooked. Less energy was released than required to do the test, which pricks the enthusiastic bubble. More work will be needed to improve the efficiency of the process before an economically viable fusion reactor can generate several times the energy needed to burn the fuel, and thus be plugged into an electrical grid.
The allure of fusion to make electricity has heated up the private sector. There are more than 10 development-phase companies in the U.S. and the U.K. competing to perfect a practical fusion reactor. Ultimately, a successful reactor would generate an enormous amount of heat, which would probably be captured via a steam cycle, just like today’s electricity generation stations that run on fission or the combustion of oil, gas or coal.
Why is achieving controlled fusion so hard? Because it takes a great deal of energy to force the atoms in the fuel (usually a form of hydrogen called deuterium) to fuse with one another. After all, it takes a fission bomb to ignite a fusion bomb. But there is a possible workaround by replacing deuterium with a form of helium (helium-3) that could have advantages. A reactor based on the fusion of helium-3 would be clean, since no nasty neutrons would be released. Today’s fission reactors produce gobs of neutrons, resulting in the spent fuel and parts of the reactor vessel itself becoming highly radioactive, essentially forever. That’s why nobody wants to store spent fuel in their backyards. Atomic energy with no radioactive waste would be a tremendous advance.
Alas, helium-3 does not exist on Earth in useful amounts, but there are hints that it does on the moon. Harrison Schmitt was the astronaut trained as a geologist who was part of the crew on Apollo 17 and one of the last people to walk on the moon. I met him at a meeting on space exploration a few years ago. He believes we should investigate helium-3 immediately: Collect some from the moon, bring it to Earth and test it as a reactor fuel.
The Chinese may have done what Harrison was suggesting. Learning more about helium-3 was likely one of the motivations for the Chinese Lunar Exploration Program.
Their 2021 trip to the moon supposedly returned a sample of something that might contain some helium-3 to investigate its potential as a reactor fuel. This is only my guess, since the Chinese space program has said nothing more about what they found or what their plans are.
Sadly, an industry observer of fusion research said many years ago that practical fusion energy is 30 years away and always will be.
In the meantime, we can be consoled by the fact that we already have a wonderful big fusion reactor — the sun — that bathes the Earth in recoverable energy, and it is safely tucked 93 million miles away. Even as the pace of wind and solar projects is increasing around the world, we’re not even close to getting all we might from the sun. More than 1,000 watts of energy comes to each square meter of the Earth’s surface when the sun is directly overhead (1,000 watts or 1 kilowatt is a bit more than one horsepower).
Sunlight is free. No wonder photovoltaic systems are so popular. So, while we wait for a safe and affordable electric generator based on fusion, we can always collect some free horsepower from our sunshine.
Richard Gelinas, Ph.D., whose early work earned a Nobel prize, is a senior research scientist at the Institute for Systems Biology. He lives in Lakebay.
For more information on the work at Livermore: The Economist; 17 December 2022. Also see links at Helium-3; Chinese Lunar Exploration Program; a list of companies working on controlled fusion.
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