Evrim Yazgin
Cosmos science journalist
What do physicists from around the country – currently gathered at the Australian Institute of Physics (AIP) annual Congress held in Adelaide – think about the news that US researchers have generated energy from a fusion reactor?
Cosmos spoke, between AIP Congress sessions, with two nuclear physicists from the Australian National University (ANU).
So, how did these experienced nuclear physicists react when scientists at the US Department of Energy’s Lawrence Livermore National Laboratory in California achieved a net energy gain from a controlled fusion reaction?
ANU’s Professor Andrew Stuchbery said that the announcement filled him with “excitement, but realistic excitement.”
Stuchbery says as significant as the result is, it will not mean all our homes are going to be powered by nuclear fusion any time soon.
“It’s an essential step on the way to eventually realising fusion power, which should be a much cleaner sources of energy than fission power. People have been striving towards achieving this outcome for decades. It is a fantastic achievement. There’s elation, but we have to be realistic. It’s not going to produce commercial fusion power next week. In fact, it’s going to take some decades. There’s still the huge problem of scaling up.”
Professor Kenneth Baldwin, also from ANU, agrees.
“I can remember back to when I was a student back in the late 70s, early 80s. There was a bit of a running joke back then that fusion is always 30 years away. Now, it’s really with us. This is a truly amazing achievement. And it’s created a great buzz around the Australian Institute of Physics Congress here in Adelaide. Everyone’s talking about it. It’s gone around the world and the entire physics community is very excited about this.
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“But I think this old adage of being 30 years away is going to come back again, and probably that’s the timescale that will be needed to turn this into a commercial fusion electricity generating system,” Baldwin told Cosmos.
“Which means, of course, that this won’t happen till the second part of the century, and it’ll be too late to help us with the fight against climate change. That means that all the heavy lifting is going to be done by renewables, solar and wind, and by nuclear fission in countries that have that.”
The facility at Los Alamos, California which achieved net energy output from fusion, used lasers to force deuterium and tritium isotopes of hydrogen (hydrogen atoms with two and three neutrons respectively) together. The laser interacts with the isotope-filled capsule, causing it to implode and squeeze the plasma inside, causing the deuterium-tritium (D+T) reaction. A tiny amount of material was used in their test.
“The energy output is significant for what went in, but it was a flash instantaneous, so scaling up means that one has to produce a lot more of these flashes per second,” explains Stuchbery. “And one has to scale up the size of the reaction chamber. And that’s not trivial.”
Stuchbery wonders how can be practically scaled up.
“It has to be scaled up in both size and in the frequency of these pulses. You do one shot with this little device, and then you need another one. There’s a lot of technical developments that need to happen before this can become commercialised, but the very fact that for the first time ever on Earth, we have induced a D+T reaction in this way is a step forward.”
Both Stuchbery and Baldwin note that this laser-induced fusion method is not the only approach being studied internationally.
No matter the method, Baldwin explains, the goal is to replicate what is happening inside our sun and other stars. The cores of these giant balls of gas see trillions of fusion reactions take place each second – spreading their energy in the form of light and heat across the universe.
The nuclear physicists discussed an alternative method of fusion being investigated which uses magnetically-confined plasma instead of laser pulses. “The idea is that you contain the plasma with a magnetic field and you pump in energy, and seek to achieve enough energy density in the plasma to induce fusion reactions,” Stuchbery explains.
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Tests of magnetically confined plasma fusion are taking place at the International Thermonuclear Experimental Reactor (ITER) based in Europe. But Australian nuclear physicists are involved in the investigations.
“ITER is a big international effort,” says Stuchbery.
“Magnetic confinement experiments are really aimed at providing a continuous generation of excess power from the fusion reaction, whereas the Livermore experiments, or pulsed experiments, are basically miniature hydrogen bombs that are set off by these massive laser pulses,” says Baldwin.
“However, the magnetic confinement system would operate continuously. Existing experiments which have been done have got very close to break even. At the Joint European Torus, for example, in the UK, have run for many seconds, but this needs to be extended to hours and days, if not continuously.”
“It’s always good to have multiple approaches to things. It’s very interesting to see the diversity and diversity is a good thing,” Baldwin adds.
In fusion reactions, most of the energy produced is in neutrons. These chargeless particles are difficult to trap, making it hard to extract that energy.
“The idea of the ITER-type experiment is that you have a blanket around the reactor that will catch that energy, but it will also make tritium which is providing fuel. But the fact that the neutron has all the energy and doesn’t have a charge and is hard to stop and transfer its energy to something else, is a is a difficulty.”
The scientists note Australia’s relatively small, but significant role in nuclear fusion research.
“I think Australia’s part would be in terms of theoretical modeling for the devices and materials development and characterisation,” Stuchbery says. Baldwin adds: “Australia, being a small country, obviously has a relatively small role to play this, but nonetheless, we’ve contributed to this magnetic confinement activity over many decades.”
Baldwin stresses fusion is a clean future energy source. He also dispels myths that, like fission, nuclear fusion can be used to create weaponry.
“Fusion is a clean form of energy source. The byproduct of the fusion reaction between isotopes of the hydrogen atom – deuterium and tritium – is helium atoms, an inert gas. From the reaction itself, there are no radioactive products. There are certainly no greenhouse gases produced. This has great environmental benefits. There might be some very slight neutron activation of the materials surrounding the fusion reactor, but this will be very low grade, and will be very short-lived depending on the materials that are used. We won’t have anywhere near the issues that nuclear fission has in terms of radioactive waste disposal. That’s a huge advantage.
“Maybe in the very long term, it will come to replace these other forms of energy, given that it offers limitless supplies of fuel with almost zero environmental consequences, and potentially the ability to generate unlimited energy in the centuries to come.”
Stuchbery shares in Baldwin’s optimism for the future, and stresses that there is much work that still needs to be done before nuclear fusion reaches its potential.
“It is exciting. But let’s not step into science fiction. But let’s not be pessimistic, either. It’s a fantastic international endeavor to pursue this goal and it’s a great success for science.”