Helion Energy, which focuses on generating zero-carbon electricity from fusion, has secured a $500 million Series E led by industry veteran Sam Altman. The Everett, Wash.-based company also announced an additional $1.7 billion of commitments tied to specific performance-based milestones.

"The funding marks the largest deal in clean energy ever and could be the beginning of a new era: abundant, clean energy from commercialized fusion technology," said Svenja Telle, an analyst at PitchBook. "[The deal] is a milestone for climate technology as the company's success could deliver practically endless amounts of low-risk clean energy while producing far less operational radioactivity and toxic waste by-products."

The company plans to use the funding in part to complete the construction of its seventh generation fusion generator, a machine that creates an excruciatingly hot chamber in which pairs of atoms can be fused together to release energy that can be turned into electricity. The machine is expected to be the first fusion device capable of achieving net electricity production by 2024.

Existing investors including Asana co-founder Dustin Moskovitz, Mithril Capital and Capricorn Investment Group also participated in the round. Helion raised $40 million at $1.25 billion valuation in September 2020.

A standout year for nuclear energy startups, VCs poured $676 million into the sector through the third quarter of 2021, according to PitchBook data. That number is more than the total amount raised by nuclear energy startups in the past five years combined.

Notable startups in the space include Commonwealth Fusion Systems, which aims to construct a fusion power plant, and Zap Energy, a developer of a compact and scalable fusion reactor. Zap Energy brought in $27.5 million in a Series B led by Addition in May. 

Even though nuclear energy can provide a safe and clean alternative source of power through either fission or fusion, the energy transition category is seen as controversial. Nuclear power often gets left out of the "clean energy" conversation due to safety concerns and unresolved questions about permanent nuclear waste storage, according to a recent Climate Tech Taxonomy report by PitchBook.

However, as COP 26 became a stage for the private sector to fully commit to investing trillions of dollars into clean technologies over the next 30 years, we will see more deals of this size soon, said Telle.

Featured image by vchal/Getty Images

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