Nuclear fusion can “fill the gaps” left by wind and solar by safely and cost-competitively cracking the toughest challenges facing global decarbonisation – albeit not until the 2040s –the boss of a Bill Gates-backed start-up commercialising the technology told Recharge.

Bob Mumgaard, CEO of Commonwealth Fusion Systems (CFS), claimed nuclear fusion can take its place as a competitive player in global energy markets in time to make an impact on the climate emergency, once it clears the big scientific hurdle facing it and others racing to prove the technology's viability.

CFS’s SPARC project with Massachusetts Institute of Technology (MIT) by 2025 aims to become the first fusion reactor to show ‘net energy gain’ – producing more energy than it consumes – by generating thermal energy that could be harnessed to produce power in a conventional steam cycle.

Once that is achieved, Mumgaard said “you’ve got a thermal system – power-dense, no-emission, dispatchable, low-marginal-cost heat” that could be deployed in scalable modules of 200MW or so that operate very much like existing gas plants, only without the carbon.

“That’s a class of energy technology that [currently] doesn’t really have a good solution.”

While wind, solar and long-duration storage can “get us a long way down the road on climate, they don’t get us all the way”, Mumgaard claimed.

The CFS chief executive said nuclear fusion (see panel at foot) “has a lot of the attributes that can fill all those gaps” – citing the decarbonisation of mega-cities such as Tokyo, or energy-hungry industries such as steel.

Mumgaard admitted that even if the science goes to plan in the middle of this decade, and first commercial systems appear in the early 2030s, deployment of commercial fusion at gigawatt scale won’t happen “until the later half of the 30s at the earliest”.

Is that really “in time to make a difference for climate change”? That was the claim made by CFS in a statement citing papers in the Journal of Plasma Physics which it said show its peers believe its technology can help deliver fusion faster, and at smaller scale than giant international ventures like the ITER project in France.

Mumgaard told Recharge that by the end of the next decade “if you look at other technologies and markets, and what’s needed, that’s in the range where you’re at the time where problems are getting really hard on carbon emissions, because you’ve taken all the easy gains.”

Bill of materials

The CFS boss is also bullish when pressed on cost – frequently cited as one of the other great unknowns of fusion power.

With the exception of the specific elements of fusion technology, Mumgaard said: “The bill of materials for these [type of] plants is pretty well established – [components such as] heat exchangers that people like Siemens make.”

A demonstrator project planned to later in the decade will also “give us some visibility” on the costs of an actual commercial system, he added.

The case made by US-based CFS – itself a spin-off from MIT and focused on the high-temperature superconducting (HTS) magnets that are key to making its version of fusion work – has attracted investments from Microsoft billionaire Gates, and global oil & gas players Equinor and Eni, among others.

Mumgaard said the existing investors “want to see a new energy technology and they have the wherewithal [to help fund it].”

But what about the massive investment that would be needed to take fusion to gigawatt-sale deployment?

“The business model itself is not very uncertain once you have something that works, and you know what it costs, and you know how it’s built

“It’s the same infrastructure that’s taken solar to scale, that’s taken wind to scale.”

'No chain reaction'

With the word ‘nuclear’ attached to a technology inevitably prompting safety questions, Mumgaard insists that fusion is in a scientifically literal sense “at the other end of the spectrum” to its cousin nuclear fusion.

“The only thing they share in common is that they deal with the nucleus (of atoms),” he said.

We don’t have any of the materials you could make a bomb out of.

“There’s no chain reaction, so there’s no ability for the chain reaction to go out of control. We don’t have any of the materials you could make a bomb out of.”

Mumgaard added: “It’s much closer to running the energy systems we run in the fossil industry. You turn it on, you shut it off.”

Meanwhile, the primary waste material, helium, is produced in quantities so small “there’s not enough to make a balloon business”.

“The whole thing is drastically different,” to nuclear fission, said Mumgaard.

Nuclear fusion - star power on earth

Nuclear fusion energy aims to harness the same reactions that power the sun to produce unlimited, on-demand, clean energy.

The process involves changing a gas to a plasma at temperatures of tens of millions of degrees, often aided by superconducting magnets, to create collisions between hydrogen atoms, tapping the energy that’s produced.

Unlike its close cousin nuclear fission – basis of the current global nuclear industry, which relies on splitting rather than combining atoms – fusion is said by scientists to present no risk of the sort of runaway reaction that led to the Chernobyl disaster.

And while it is not waste-free, the by-products are said to be low and short-lived compared to fission, and much more easily manageable.