AS THE world tries to wean itself off fossil fuels, scientists are racing towards one of the biggest breakthroughs in history that could provide virtually unlimited energy.

Theoretical physicist Professor Steven Cowley spruiked the immense potential of fusion, which he described as a “perfect energery source”, in a “deliberately provocative” talk at Syndey University on Thursday night.

“It’s the perfect way to make energy except for one problem,” he said. “We don’t know how to do it.

“But if it can be made to work, it will make a major difference to the future of our world.”

Fusion is a nuclear reaction in which atomic nuclei of low atomic number fuse to form a heavier nucleus with the release of huge amounts of energy. It’s effectively the process that occurs at the centre of stars such as our sun — which converts 600 million tons of hydrogen into helium every second. Replicating it would be like building an Earth-dwelling star. The challenge then is to find a cost effective way to turn that into electricity.

By conducting experiments, scientists hope one day to be able to harness that power and usher in a new form of zero emission clean energy.

“ Using fusion, there would be enough hydrogen in the ocean to power the world for 10 trillion years,” Prof Cowley, who is an international authority on nuclear fusion and astrophysical plasmas, told the audience.

But of course, that would be overkill “because there will be no world in 5 billion years (when the sun finally dies),” he pointed out.

The former chief executive officer of the UK Atomic Energy Authority, Prof Cowley has been involved with a number different fusion projects. But at the forefront is a global initiative in the south of France called ITER, or the International Thermonuclear Experimental Reactor.

It’s funded by the European Union, the US, China, Russia, Japan, India and South Korea — and Australia has also recently joined the party.

“I’m not going to talk about its budget because it’s just a disaster,” Prof Cowley joked.

At this point, costs have blown out to at least 15 billion euros ($A23 billion).

The incredible machine is still years away from getting switched on but when it does it will generate a super-hot cloud of hydrogen that will rotate faster than the speed of sound while being bombarded with surges of electric current, causing the core of the machine to reach temperatures of more than 150 million degrees Celsius. The problem that has so far plagued scientists is producing a plasma free of pesky turbulence, which can destabilise the energy producing reaction.

Unlike other forms of nuclear power, there is almost no waste considerations, making it a far safer and environmentally friendly way to meet our energy needs.

“The waste problem from fusion is trivial,” Prof Cowley told the audience at Sydney Uni on Thursday night.

Power prices in Australia continue to rise but countries with a huge population, such as China, are desperate to find a fusion solution to their future energy needs.

China plans to build it’s own large fusion reactor, twice the size of ITER. So if all goes according to plan, when the machine in France does begin conducting experiments about 2025, the country will then look to kick things up a notch.

Earlier this year, the Australian National University gave China the keys to its $35 million nuclear fusion stellarator as part of a technology exchange with China. The US-designed stellarator and the Russian-invented Tokamak are the two devices most likely to make commercial fusion viable. China has four Tokamaks and is keen to bolster its future potential to generate fusion power.

In fact, Australia has become an increasingly important player in the march towards fusion energy. In September 2016 Australia became the first non-member state to enter a formal collaborative agreement with ITER.

And it’s all thanks to the development of some innovative tech designed to keep the walls of the reactor from overheating, according to John Howard, the head of the Plasma Research Laboratory at the Australian National University College of Physical and Mathematical Sciences.

“Australia has come in through the back door because we developed technologies that are valuable for ITER,” he told news.com.au in November.

There’s no doubt going to be plenty of bumps in the road but when ITER gets fired up about 2025 before an all-important 2035 experiment, the world will be watching.

“This is going to be the biggest physics experiment on the planet when it’s completed,” Prof Howard said, confirming that he believed nuclear fusion would one day be a commercially “viable proposition” to supply the world’s electricity.

“In my view if the world was fair dinkum about green house gases and alternative energy sources we’d be looking at nuclear energy in the short term and fusion energy in the long term,” he said.

Prof Cowley is equally optimistic it will happen in his lifetime.

He hopes to be sitting at ITER watching the first fusion reaction take place. “It will be a historic moment,” he said.