Helion Energy is standing by its 2028 deadline to deliver electricity to Microsoft, despite mounting scepticism from rivals in the nuclear fusion sector. Chief financial officer Pragav Jain told the Financial Times the company remains on track to meet its milestone, even though no fusion company has yet achieved commercial power generation.

Helion, valued at $5.4bn after raising $1bn from investors including OpenAI's Sam Altman and Peter Thiel, faces criticism for its ambitious timeline. Industry executives question how the company will manage high-energy neutrons that can damage reactor structures. Helion claims to be developing a self-healing material but has disclosed relatively little about its scientific progress, citing intellectual property concerns.

The company is building a sub-scale commercial unit in Washington state for Microsoft while also developing a 500-megawatt plant with steelmaker Nucor for 2030. Helion's approach differs from traditional fusion designs by generating electricity directly from magnetic field changes rather than using turbines, which investors describe as the "holy grail" of fusion technology.