Last Energy's steel-cased reactor bet: $100M Series C, 5MW Texas A&M pilot due 2026

Last Energy builds the PWR-20, a 20-megawatt pressurized-water micro-nuclear plant designed for factory fabrication and rapid on-site assembly, targeting data centers, heavy industry and defence installations.

That factory-built 20 MW reactors can be privately financed, licenseable in years, and deployed in thousands at customer sites — ending nuclear's gigawatt-project era.

$100M Series C led by Astera Institute (Dec 2025); $40M Series B in 2024 brought total to $64M (ESG Today)

Kugelmass founded Last Energy in 2019 in Washington, D.C., after years of trying to convince people nuclear mattered, betting that small reactors could be built like manufactured products rather than one-off megaprojects. Instead of courting utilities, the company went after private industrial and data-center buyers, and chose a proven pressurized-water reactor lineage to keep licensing risk low.

In 2024 Last Energy closed a $40M Series B (total $64M), signed agreements for 80 units — 39 of them for data centers — and set a goal of 10,000 units in 15 years. By February 2025 it had secured a Texas site for 30 microreactors; in September 2025 it signed an £80 million, subsidy-free agreement with DP World to build its first unit at London Gateway, after the UK's ONR completed a preliminary design review of the PWR-20 in June 2025. In December 2025 a $100M Series C led by Astera Institute fully funded a 5MW pilot reactor on a site leased from Texas A&M, with startup hoped for in 2026 and 20MW commercial production in 2028.

Still running: the Texas A&M pilot is fully funded and under development, 80+ unit agreements stand, but no Last Energy reactor has yet generated power.

Targets private industrial and data-center buyers who cannot wait for gigawatt plants, betting a 20MW unit can be deployed on an existing site in about 24 months.

Owns and operates plants on customer property, bypassing transmission-grid expansion and utility procurement cycles — the usual decade-long delays.

Reuses the proven pressurized-water reactor design from the NS Savannah to cut licensing and fuel-supply risk versus novel SMR designs.

Frames nuclear as a manufactured product at fleet scale — 10,000 units in 15 years — with steel-encased cores eliminating refueling, servicing and separate waste disposal.

A proven design plus a productized, privately financed model can raise hundreds of millions before a single watt flows — but the fleet bet pays off only when the first reactor actually runs.

As of 2026-09-02, Last Energy's 5MW pilot reactor at the Texas A&M site is fully funded by the December 2025 Series C and targeted for startup in 2026, with the 20MW PWR-20 entering production in 2028. The DP World London Gateway project, described as the company's first unit, aims for operations around 2030 pending UK licensing expected to conclude by the end of 2027. The company still lists more than 80 commercial agreements, but no unit has yet generated power, so the manufacturing-and-licensing thesis remains unproven.