As world leaders meet in Paris to agree a legal framework aimed at limiting use of fossil fuels and the resulting rises in global temperatures, a UK company says it could be as little as five years from making “reactor relevant” fusion, a potential game changer in energy production.

A British company believes it is within five years of achieving “reactor relevant” fusion, a major landmark in the six decade long scientific search for the veritable Holy Grail of energy production.

Fusion is how stars produce energy. It occurs when the nuclei of light atoms, such as hydrogen, are fused together under extreme pressure and heat.

Tokamak Energy, from Oxfordshire, believes that the third version of their compact, spherical tokamak reactor will be able to reach temperatures of 100 million degrees Celsius by 2020. That’s seven times hotter than the center of the sun and the temperature necessary to achieve fusion. Such a temperature fuses hydrogen atoms together, releasing energy, which differs from fission reactors that work by splitting atoms at much lower temperatures.

Such an achievement wouldn’t mean a rapid rollout of a global fusion electricity network, but would be a significant step to achieving this by 2050, potentially making an enormous contribution both to world energy supplies and reducing carbon emissions.

In Paris world leaders are meeting to try to reach an agreed framework for action aimed at stabilizing atmospheric concentrations of greenhouse gases (GHGs). Governments hope the summit will end on December 11 in a deal that will herald a shift from rising dependence on fossil fuels since the Industrial Revolution to cleaner energies such as wind or solar power.

Key to Tokamak Energy’s success is the spherical shape of its tokamak - a device using a magnetic field to confine plasma - and thin high temperature superconductor strips.

“Here what we’re developing is building these small tokamaks, like ST25, and then we’ve got other devices using key technologies which are high temperature superconductors and spherical tokamak shapes,” senior Tokamak engineer Bill Huang told Reuters. “So we’ve got a slightly different shape from traditional fusion and this allows us to get a higher plasma pressure for a given magnetic field. It’s a measure of efficiency called beta, and by using this improved efficiency it means that the overall size of our device is actually quite a bit smaller.”

Tokamak Energy says its technology would be similar in costs to a nuclear fission plant, but without any fissile material and with no risk of meltdown.

The company, a World Economic Forum Technology Pioneer, says its compact design means fusion could be generated in far smaller reactors than assumed possible by scientists until recently.

Huang says that its current ST25 reactor has already reached fusion temperatures in short bursts, but hopes its third reactor, ST40 - currently being completed - will enable it to produce “reactor relevant” conditions.

“This (ST25) will allow us to get very high temperatures for a short amount of time but what we’re looking to do is generate these high temperatures which are reactor relevant, so we’ve set ourselves a 100 million degree challenge, and we’re aiming to get 100 million degrees in that (ST40) device,” said Huang.

The company is three stages into its five stage process - each involving a new reactor.

Tokamak CEO David Kingham believes it will be possible for his team to transfer energy to the grid by 2030.

“We want to get within five years to an energy gain, and from there we want to go on in ten years to get to first electricity, a device where we can demonstrate production of electricity from fusion, but it may be 15 years before we get energy to the grid in significant quantities,” said Kingham.

He added: “Fusion is one of those technologies which, if it could be harnessed, could be scaled up rapidly to be deployed world-wide by 2050 and could make a very big difference to carbon emissions and therefore to climate change from 2050 onwards.”

Tokamak Energy has developed its own magnets using novel high temperature superconductors and believes that this new material could be used to construct even more powerful magnets to keep the hot plasma in position inside a power generating tokamak, at the fusion reactor’s heart.

The ongoing failure of the multi-billion dollar International Thermonuclear Experimental Reactor (ITER) project in France has encouraged many small companies to take advantages of advances in various technologies to attempt to make fusion themselves.

A number of high-profile investors, such as Microsoft’s Paul Allen and Amazon’s Jeff Bezos, are backing various small-scale fusion projects. Investors are attracted to the sheer scale of eventual return on offer in an era when the world is turning its back on dwindling fossil fuel stocks and looking for cleaner energy sources. The fact that many different routes could be developed to achieve fusion, as opposed to a ‘winner-takes-all’ race where only one invention succeeds, is also attractive.

One of the company’s largest investors - and the first to stump up funds - is the Rainbow Seed Fund, co-managed by Mark White. “I think this opportunity here is possibly one of the most spectacular combinations of risk and reward that I’ve ever seen. There are undoubtedly many challenges still remaining,” he said.

Such challenges include making exceptionally strong magnets from high temperature superconductors.

White says that Tokamak Energy’s superconducting magnet inventions will also help investors like him achieve a good return on their money. Additional factors make the venture attractive.

“First of all they (fusion reactors) can be constructed in a factory, so you’re talking about economies of scale; and the second key thing is the way in which the grid itself, the future grid, is likely to be more dispersed than current central power generation units, one to two gigawatts per power station. The devices we’re talking about here are likely to be in the order of 100 megawatts, considerably smaller than those units, and that puts them into the sort of power output bracket that becomes really very interesting for large mobile uses, such as some that you might see in the defense sector - aircraft carriers, submarines, for example.”

Other companies in the hunt for a fusion breakthrough include Dynomak, developed by researchers at the University of Washington in Seattle, which has proven that their concept works. The next step is to scale it up so they can achieve the temperatures needed to start and sustain a fusion reaction.