The deal follows an earlier investment in 2021 in CFS – founded in 2018 in Cambridge, Massachusetts, as a spin-out from the Massachusetts Institute of Technology (MIT) Plasma Science and Fusion Center. Financial terms have not been disclosed for either investment.

In addition to increasing its stake in CFS, Google has also signed a PPA for 200 MW of electricity from CFS’ inaugural ARC power plant in Chesterfield County, Virginia. CFS plans to connect the plant to the grid in the early 2030s. Google also has the option to offtake power from additional ARC power plants as they are developed.

At its core, fusion is the same process that powers the sun and stars. It involves taking light atomic nuclei and heating them to extreme temperatures over 100mn °C at which point the fuel becomes a plasma. When it becomes dense enough, the nuclei fuse, releasing a tremendous amount of energy that can be captured to generate carbon-free electricity. This is different from nuclear fission, a process that splits atoms to release energy.  

CFS is currently building its SPARC (smallest possible, affordable, robust, compact) reactor at the company’s headquarters in Devens, Massachusetts. It will use custom high-temperature superconducting (HTS) magnets in a doughnut-shaped fusion tokamak unit to heat two forms of hydrogen – deuterium and tritium – which when they fuse (into an atom of helium) create continuous flow of highly energetic plasma contained within the tokamak’s magnetic field. This plasma releases energy that is captured as heat by a liquid ‘blanket’, which is then transferred to a steam turbine to generate power.  

In the past, limitations on magnet technology required tokamaks to be enormous in size to achieve the magnetic field needed to achieve net energy. CFS’ HTS magnets, developed in collaboration with MIT, allow for significantly stronger magnetic fields that can enable smaller, high performing, fusion systems at significantly lower cost, according to the company.  

CFS plans to show that its SPARC reactor can output more energy than it needs to power the reaction – known as ‘net energy gain’, or ‘Q>1’. If successful, this will act as the basis for CFS to set up its first ARC reactor in Chesterfield that will generate 400 MW of electricity, a level comparable to a utility-scale natural gas power plant’s output, says the company.  

Commercialising fusion is immensely challenging, and Google admits ‘success is not guaranteed’. However, Michael Terrell, Head of Advanced Energy at Google, says: ‘By entering into this agreement with CFS, we hope to help prove out and scale a promising pathway toward commercial fusion power. We’re excited to make this longer-term bet on a technology with transformative potential to meet the world’s future energy demand.’

‘Fusion power is within our grasp thanks in part to forward-thinking partners like Google, a recognised technology pioneer across industries,’ says Bob Mumgaard, CEO and Co-founder of CFS. ‘Our strategic deal with Google is the first of many as we move to demonstrate fusion energy from SPARC and then bring our first power plant online. We aim to demonstrate fusion’s ability to provide reliable, abundant, clean energy at the scale needed to unlock economic growth and improve modern living – and enable what will be the largest market transition in history.’

An alternative approach

Earlier this year, in January, fusion start-up company Helion reported that it had raised $425mn to help build its first commercial-scale fusion reactor to supply technology giant Microsoft with electricity by 2028.  

Unlike CFS, Helion’s technology combines magnetic and inertial (physical and temperature-based) confinement techniques in an hourglass shaped field-reversed configuration reactor to produce cyclical bursts (‘pulses’) of fusion reactions. As new fusion energy is produced, the plasma expands, pushing back on the magnetic field from the machine’s magnets. By Faraday’s Law, the change in the field induces a current, which is directly recaptured as electricity, allowing Helion’s fusion generator to skip the steam cycle of existing tokamak designs.  

The company says that directly capturing electricity from the fusion reaction will lead to a more efficient and faster path to grid integration.

Helion’s latest prototype, Polaris, is based in Everett, Washington.