Nuclear fusion powers the sun and the stars. It can provide abundant energy on Earth too, which is why scientists have been working to tap it. Researchers in Britain recently made a major breakthrough in the bid to harness fusion energy.
During nuclear fusion experiments in Oxfordshire, southern England, scientists managed to release a record amount of energy. That landmark event came amid the clamour for a new generation of nuclear reactors to reduce nuclear waste. Present-day reactors employ nuclear fission to generate power, and at least 400 commercial reactors now provide electricity to more than 30 nations.
When nuclear fusion becomes viable enough to provide sustained energy, it will eliminate nuclear waste. The Joint European Torus record gives hope that the day of nuclear fusion as a source of power is not far.
Here’s an explainer on why the JET nuclear fusion record is a milestone.
What’s nuclear energy?
Nuclear power is the energy gained from fission (splitting atoms) or fusion (combining atoms). All nuclear plants worldwide use nuclear fission, which releases heat (energy) that turns water into steam to run turbines and create electricity.
Fusion too releases energy, but scientists have not been able to generate power in a sustained manner. That has been a stumbling block in harnessing energy from nuclear fusion.
What’s the difference between nuclear fission and nuclear fusion?
Fission and fusion release incredible amounts of energy, but in opposite ways. During fission, a single heavy atomic nucleus is split, while fusion requires combining two or more light atoms.
Uranium, plutonium, or thorium are used for fission, which results in high levels of radioactive waste. Moreover, these elements are very expensive. During nuclear fusion, no radioactive waste is produced; helium atoms are a by-product.
Why is nuclear fusion attractive?
Energy from nuclear fusion is an attractive prospect because it does not release greenhouse gases (1kg of fusion fuel contains about 10 million times as much energy as 1kg of coal, oil or gas). Since it’s a cheap and clean energy source, experts believe fusion can help address climate change.
The hydrogen atoms (isotopes) fused are deuterium and tritium. Deuterium is available in seawater, but tritium is extremely rare and produced in nuclear reactors. So fusion plants will have to make tritium fuel by using high-energy neutrons, released during fusion, to split lithium into tritium and helium.
Is nuclear fusion safe?
Nuclear fusion is safer than nuclear fission because energy production is not based on a chain reaction. Since plasma has to be maintained at very high temperatures, the reactor stops as soon as plasma cools down. So fusion reactors are considered safe.
Fusion reactors cannot be used to make nuclear weapons since a limited amount of fuel is used at a time, and it’s fed continuously. So there’s never enough fuel to produce enormous power instantaneously.
How was the fusion experiment in Britain conducted?
Inside the doughnut-shaped JET, a tiny amount of fuel comprising deuterium and tritium was heated to 150 million degrees Celsius, 10 times hotter than the centre of the sun, to create plasma (an ionised state of matter). The atomic nuclei can fuse together to form new elements and release vast amounts of energy.
What happened during the experiment?
The fusion experiment at the Joint European Torus lab generated 59 megajoules of heat — equivalent to about 14kg of TNT — during a five-second burst of fusion. That is more than doubled the previous record of 21.7 megajoules set in 1997 by JET. That’s why it’s seen as a significant milestone towards making fusion a viable and sustainable low-carbon energy source.
Pound for pound (gram for gram) it releases nearly four million times more energy than burning coal, oil or gas, and creates virtually no waste, an AFP report said.
Why is the JET nuclear fusion experiment a major milestone?
“Five seconds doesn’t sound like much, but if you can burn it for five seconds, presumably you could keep it stable and keep it burning for many minutes, hours, or days, which is what you are going to need for a proper fusion power plant. It’s the proof of that concept that they have achieved,” the Guardian quoted Mark Wenman, a reader in nuclear materials at Imperial College London, as saying.
The results “are the clearest demonstration worldwide of the potential for fusion energy to deliver safe and sustainable low-carbon energy,” the UK Atomic Energy Authority said.
“These landmark results have taken us a huge step closer to conquering one of the biggest scientific and engineering challenges of them all,” Ian Chapman, chief executive of the UKAEA, told the Guardian. “It’s clear we must make significant changes to address the effects of climate change, and fusion offers so much potential.”
What are the hurdles in developing nuclear fusion?
High electricity requirement is a major problem. Since fusion occurs only at extremely high temperatures, large amounts of electricity are needed to create plasma. More electricity is required to keep the fusion going. So it’s imperative to generate power in excess.
Fusion experiments are conducted in a machine called a tokamak, and special materials are required to withstand the reaction and the high heat. And large quantities of helium are needed to cool the tokamak.
What’s the future of fusion experiments?
A more advanced version of JET, called Iter, is being built in southern France with the support of the US, China, the European Union, India, Japan, Korea and Russia. The assembly of the first-phase machine will conclude in December 2025 with First Plasma, signalling the start of Iter operations. When the full-power fusion operation is launched in 2035, it’s expected to generate excess heat to keep the plasma at high temperatures.
If the Iter experiments are successful, a demonstration power plant will be built in Europe, capable of producing more electricity than it consumes. It will allow the plant to be hooked up to the grid.
