9 companies, privately held.
Helion Energy
Fusion · Pulsed magneto-inertial fusion developer (Orion plant, Malaga, Washington)
Latest (Jun 16, 2026): Orion: Radioactive Materials License and Radioactive Air Emissions License for the Orion facility (state radiation licences; Helion's claim that these are the licences needed for plant operations is its own) (permission issued)
Open profile →Quaise Energy
Next-generation geothermal · Superhot geothermal developer using millimetre-wave drilling
Latest (Sep 3, 2026): Quaise Energy updates its private offering notice: $179.3 million of equity sold
Open profile →Radiant
Advanced nuclear · Developer of the Kaleidos portable microreactor
Latest (Dec 30, 2025): Radiant reports $268.8 million of equity sold in a private offering
Open profile →Commonwealth Fusion Systems
Fusion · Tokamak fusion developer (SPARC in Massachusetts, planned ARC plant in Virginia)
No developments in the current window yet.
Open profile →Form Energy
Long-duration storage · Iron-air batteries designed for multi-day storage
No developments in the current window yet.
Open profile →Sage Geosystems
Next-generation geothermal · Long-duration storage · Geothermal power and underground pressure-based energy storage
No developments in the current window yet.
Open profile →Zap Energy
Fusion · Sheared-flow Z-pinch fusion developer
No developments in the current window yet.
Open profile →TerraPower
Advanced nuclear · Developer of the Natrium sodium-cooled reactor with molten-salt energy storage
Latest (May 23, 2026): Natrium Kemmerer Unit 1: DOE account of the permit and the start of plant construction (construction)
Open profile →Kairos Power
Advanced nuclear · Developer of the fluoride salt-cooled high-temperature reactor (KP-FHR)
Latest (Sep 21, 2026): Hermes 2 Demonstration Plant: Samsung C&T strategic investment in Kairos Power (company level), binding term sheet, subject to regulatory approvals; stated purpose is Hermes 2 delivery (conditional)
Open profile →Coverage is not an offer to invest. Private ownership does not imply available shares. Sector labels are Power Inflection’s own coverage classification, not company claims.
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