New Jersey-based fusion technology company Thea Energy has announced certification of its preconceptual Helios pilot plant design by the US Department of Energy (DOE). This followed a detailed review by a panel of independent fusion experts from national laboratories, research institutions and universities focused on fusion.
The preconceptual design review marks completion of the final major milestone in DOE’s Milestone-Based Fusion Development Program (the Milestone Program). Thea Energy (formerly Princeton Stellarators) is the first awardee company to receive certification.
The US Milestone Program was launched by DOE in September 2022, although it was authorised by the Energy Act of 2020 and received initial funding in Fiscal Year 2022. The programme aims to accelerate fusion commercialisation through public-private partnerships. Thea Energy was one of the first eight companies selected for support in May 2023. However, agreements were not signed with the awardees until more than a year later in June 2024.
The Milestone Program was modelled after the NASA Commercial Orbital Transportation Services (COTS) programme. It supports companies focused on grid-scale power through non-dilutive capital and external validation, where funds are only paid when key milestones that de-risk fusion technologies are completed and approved by a review panel.
DOE approved completion of the Helios preconceptual design following a detailed report review by independent experts. Members of the DOE review team visited Thea Energy’s headquarters in Kearny as part of the certification. Reviewers focused on comprehensively validating that the company has a system architecture and a robust path toward deploying a fusion power plant.
Other milestones completed by Thea Energy since selection in 2023 include the successful performance of the world’s first superconducting planar coil magnet array and the down selection to a family of stellarator plasma configurations.
“This final design milestone, now certified by the DOE, substantiates the validity of the planar coil stellarator and shows a clear pathway to a deployable power plant,” said Brian Berzin, co-founder and chief executive officer of Thea Energy. “Practicality, conservatism and engineering margins are emphasised in Helios, and the DOE has recognised those differentiators in this design.”
He added: “Working with the DOE across this milestone, and eight prior, ensured team Thea approached each cornerstone with rigor, scrutiny and thoroughness. Now is the time to prioritise fusion and the teams driving meaningful progress, and we strongly support the expansion of the Milestone Program to align with the industry’s commercialization goals.”
Dr Jean Paul Allain, Associate Director for fusion energy sciences in the DOE Office of Science, noted: “The inaugural period of the Milestone Program’s goal is to see companies demonstrate critical underlying technologies while on the path to a preconceptual fusion pilot plant design. Thea Energy tackled key milestones swiftly and enthusiastically leading to this in-depth design for a modernised stellarator system – summarised in a 200-page report to the DOE. The Milestone Program mandates a heightened level of accountability from awardees, and we look forward to seeing Thea Energy’s continued momentum.”
Thea Energy is aiming to operate Helios in the 2030s following Eos, its large-scale demonstration system that is designed to create power-plant-relevant, steady-state fusion. Eos will directly benefit from the breakthroughs highlighted in the company’s Helios design and is scheduled to be online by 2030. Thea Energy is currently in conversations with five states for the siting of Eos and expects to select and announce a location for the integrated system in 2026.
Princeton Stellarators was founded in 2022 as a spin-out from the Princeton Plasma Physics Laboratory (PPPL) and Princeton University. It changed the name to Thea Energy in 2023. The company is developing a simplified stellarator fusion reactor that replaces complex “twisty” magnets with an array of hundreds of small, computer-controlled planar (flat) coils.
