Investments in nuclear fusion have surged in the past year as new breakthroughs hold out the hope of finally tipping the balance towards what would be a clean, virtually limitless supply of electricity after nearly six decades of promise.
Over the past 12 months, US$2.8bn (£2.5bn) has been poured into the sector globally, compared to about US$2bn a decade ago.
Corporates believe in its potential too, for according to a survey conducted by the Fusion Industry Association, more than 93% of companies believe fusion power will feed electricity into power grids by 2030.
First Light, General Fusion, Helion, and TAE are among several companies looking to commercialise those years of public research by proving fusion power can work.
"I couldn’t be more optimistic," said Silicon Valley venture capitalist Sam Altman, who recently invested US$375mln in US fusion start-up Helion. He told FT, that in addition to solving the climate crisis, less expensive energy also transforms society.
UK companies like Tokamak Energy and First Light Fusion, both based in Oxford, have reported fusion breakthroughs.
Chinese technology giant Tencent invested US$45mln in First Light in February, bringing outside backing to US$107mln for the company, which was launched in 2011.
When Oxford University spinout First Light Fusion announced it had achieved fusion faster and cheaper than competitors, hopes were raised that the long search for a feasible form of energy might finally be around the corner.
The UK Atomic Energy Authority (UKAEA) is also developing plans for a prototype fusion power plant as part of its support for the technology.
General Fusion, a company backed by Microsoft and Amazon's Jeff Bezos, won UKAEA approval to build and operate a nuclear fusion demonstration plant in the UK, with the start of operations planned in 2025.
Outgoing Prime Minister Boris Johnson said in 2019 that Oxford scientists are close to "creating commercially viable miniature fusion reactors for sale around the world", and added, "Now I know they have been on the verge for some time. It is a pretty spacious kind of verge."
Last year, when he called the technology an "exciting innovation that could super-charge our efforts to #BuildBackGreener," eight new companies have entered the fusion race, according to the Fusion Industry Association.
According to the association's chief executive, Andrew Holland, nuclear fusion is on a path to "commercial relevance" at a time when new clean energy options are desperately needed.
"With investment accelerating, it is increasingly likely that commercial fusion will become a reality within the next two decades, providing the basis for prosperity, safety, and security, for many years to come, " he added, reports Telegraph.
Though a usable scale of nuclear fusion has been tried for decades by scientists, nuclear fusion is the result of fusing together nuclei, which releases energy.
The reaction powers the sun and, in theory, could supply earth with abundant, clean energy, but replicating the reaction on earth is extremely difficult, requiring massive amounts of heat and pressure.
So far, scientists have not been able to produce more energy from the reaction than it takes to trigger it - though some are making progress.
Earlier this year, scientists in Oxfordshire’s Culham Centre for Fusion Energy in Oxfordshire doubled the previous record for energy generated by fusion power, delivering 59 megajoules for five seconds from the Joint European Torus facility.
Last year, UKAEA's Mega Amp Spherical Tokamak (MAST) Upgrade experiment, also at Culham, delivered a tenfold reduction in heat "from a blowtorch level down to more like you'd find in a car engine".
Government efforts carry on. It was end-2020 when the UK government invited communities to volunteer a site for a fusion reactor prototype that would put electricity on the grid.
The project, called Spherical Tokamak for Energy Production (STEP), began in 2019 with an initial £222mln over five years to develop a design, with the UKAEA saying construction could begin as soon as 2032, with operations by 2040.
The plant aims to generate a "near-limitless" source of low-carbon energy.