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Last EnergyPWR-20 microreactor developer with aggressive 80+ MoU pipeline. Deployment claims disputed by independent assessors
MoU Pipeline
80+ Memoranda of Understanding
Mostly Eastern Europe + UK + Texas; conversion to firm contracts pending regulatory clarity
PWR-20 Output
20 MWe per unit
Intentionally small; targets industrial co-location vs grid-scale utility deployment
Capital Raised
~$140M+
incl. a $100M Series C (Dec 2025) led by the Astera Institute
First US Deployment
Texas A&M RELLIS pilot
targeting criticality by mid-2026; Wales site-licence decision targeted 2027
Total raised: ~$140M+ equity · Latest valuation: Undisclosed
| Round | Date | Amount | Valuation | Key Investors |
|---|---|---|---|---|
| Seed | 2020 | Undisclosed | - | Bret Kugelmass (founder, ex-Energy Impact Center) |
| Series A | Oct 2022 | $24M | - | Gigascale Capital (lead)MCJ CollectiveValor Equity PartnersMaC Venture Capital |
| Series A Extension | 2024 | ~$15M (reported) | - | Existing investor syndicate |
| Series C | Dec 2025 | $100M | - | Astera Institute (lead)Galaxy InteractiveGigafundWoori Technology Investment |
| System | Type | Status |
|---|---|---|
| PWR-20 | 20 MWe small pressurized water reactor (intentionally small, factory-built, modular) | Design + initial manufacturing; first commercial site pending regulatory approval |
| Modular Deployment Model | Container-shipped reactor + power-block units; 24-month site-to-energy claim | Aspirational. No commercial unit operating |
Bridgend Wales site lease for first European deployment; UK / Wales regulatory engagement underway.
Multiple letters of intent with Polish industrial companies; targets coal-replacement and industrial heat.
Texas-sited MoUs for data-center and oil-gas industrial customers; Texas regulatory environment more permissive than federal NRC.
Climate-focused VC; lead Series A investor.
Earlier-stage backer; energy-tech thesis.
Bret Kugelmass (also founded the Energy Impact Center think tank) launches Last Energy in Washington, DC
20 MWe small pressurized water reactor concept; intentionally small + factory-built + modular
Gigascale Capital leads; first significant institutional round
Site rights secured at Bridgend Wales for first European deployment
80+ Memoranda of Understanding signed across Eastern Europe + UK + Texas; mostly with industrial customers + data-center developers
MIT + IAEA + nuclear-industry analysts publicly question whether Last Energy's 2025-2027 deployment claims are achievable given NRC + EU regulatory timelines
Initial PWR-20 module manufacturing begins; deployment at Wales site targeted but regulatory path not yet secured
Plans a PWR-20 pilot at Texas A&M-RELLIS (Bryan, TX), its first US deployment, targeting criticality by mid-2026; also plans 30 microreactors in Haskell County, TX for data centers
Oversubscribed round led by the Astera Institute (Galaxy Interactive, Gigafund, Woori); lifts equity raised past ~$140M
Four 20 MWe units planned at the decommissioned Llynfi coal site (Bridgend); UK site-licence decision targeted Dec 2027 after a completed Preliminary Design Review
Developer of the PWR-20 20 MWe pressurized water reactor. Targeting UK and Texas siting. Aggressive 2025-2026 deployment claims are disputed by independent assessors. Last Energy was founded in 2020, is headquartered in Washington, DC and employs ~100.
Last Energy has raised ~$140M+ equity in total at a Undisclosed valuation, based on the funding rounds Sterling tracks.
Sterling groups Last Energy in the Nuclear sector, alongside NuScale Power (SMR), Oklo (OKLO), NANO Nuclear Energy (NNE), TerraPower (private), X-energy (private) and Kairos Power (private).
If you are researching Last Energy, also look at NuScale Power (SMR), Oklo (OKLO) and NANO Nuclear Energy (NNE). You can compare all of them side by side or browse the full Nuclear sector on Sterling.
