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Fusion energy developer Helion Energy announced Tuesday that it's closed a $425 million Series F.

Why it matters: The Sam Altman-backed startup expects to begin generating electricity as soon as this year.

The big picture: Helion is among a handful of startups racing to develop fusion energy, which promises near-limitless zero-emissions electricity.

The moonshot technology has attracted intense interest amid the recent boom in power-hungry AI and data centers.

The latest: Helion's all-equity round pushed the startup's post-money valuation past $5.4 billion.

Lightspeed Venture Partners and SoftBank Vision Fund 2 participated in the round, as well as existing investors Altman, Mithril Capital, Capricorn Investment Group, Nucor, and Facebook co-founder Dustin Moskovitz, through Good Ventures Foundation.

Altman previously invested $375 million in Helion as part of its $500 million Series E in 2021. The company has now raised more than $1 billion since its founding in 2013.

What we're watching: The Everett, Wash.-based startup has said its Polaris fusion system could generate more electricity than it consumes as soon as this year — a "net generation" benchmark thought to be years away at other startups. 

"This year, we will accelerate our testing program with the goal of demonstrating our ability to create electricity from fusion," CEO David Kirtley told Axios in a statement. 

"This goal is beyond just net generation and is about demonstrating that we can create electricity from fusion."

Helion raises $425M Series F for fusion energy

The Sam Altman-backed startup expects net output this year.

Illustration of a road leading to a glowing atom on the horizon

Fusion energy developer Helion Energy announced Tuesday that it&#x27;s closed a $425 million Series F.Why it matters: The Sam Altman-backed startup expects to begin generating electricity as soon as this year.

Helion raises $425M Series F for fusion energy

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