BREAKING Last Energy closes oversubscribed $100M Series C, Dec 2025 Pilot reactor aims to power Texas A&M-RELLIS grid by mid-2026 800+ nuclear experts interviewed on Titans of Nuclear Plans for 30 microreactors in Haskell County, TX Named to TIME100 Climate 2024 Total raised: roughly $164M since 2019 BREAKING Last Energy closes oversubscribed $100M Series C, Dec 2025 Pilot reactor aims to power Texas A&M-RELLIS grid by mid-2026 800+ nuclear experts interviewed on Titans of Nuclear Plans for 30 microreactors in Haskell County, TX Named to TIME100 Climate 2024 Total raised: roughly $164M since 2019
Person • Nuclear
Bret Kugelmass, founder and CEO of Last Energy
Glasses on, schedule in mind. The roboticist who decided atomic power should ship like an appliance.
Founder • Engineer • Podcast Host

Bret Kugelmass

He interviewed 800 nuclear experts, then concluded the reactor was never the problem. The construction schedule was. So he started building plants in a factory.

Last Energy • CEO Austin, Texas PWR-20 Titans of Nuclear
The Pitch

Make nuclear boring. On purpose.

Most nuclear founders sell you the future: a reactor that runs on something exotic, cooled by something clever, decades from a permit. Bret Kugelmass sells you 1968. His company, Last Energy, builds a 20-megawatt pressurized water reactor using physics the industry settled half a century ago, then ships it in modules that bolt together on a concrete pad. The radical part is not the machine. It is the refusal to reinvent it.

That refusal came from homework. Before Last Energy raised a dollar of construction money, Kugelmass sat behind a microphone for the Titans of Nuclear podcast and worked through more than 800 interviews with engineers, regulators, operators, and executives. Somewhere in that marathon he counted dozens of next-generation startups chasing novel reactor designs, and he noticed they kept tripping over the same root. The cost was not the steel. It was the calendar. When a megaproject takes a decade, interest on borrowed money piles up until it swallows the economics. By his accounting, roughly 60 percent of nuclear's levelized cost is the bill for time.

"We're innovative in the way that we are not trying to be overly innovative. We don't reinvent the reactor core, the physics, the chemistry or the materials."

So Last Energy attacks the calendar. Standardize the unit, build it in a factory, truck it to the site, and finance it the way you finance a wind farm rather than a cathedral. The fuel is off-the-shelf. The footprint is small enough to park next to a steel mill, a data center, or a campus. The first paying customers were lined up in the United Kingdom, Poland, and Romania - markets hungrier for fast nuclear than the slow-permitting US. Then the company planted its flag in Texas.

Kugelmass did not arrive from inside the nuclear priesthood. He grew up in Nassau County on Long Island, studied math at Stony Brook, then took a master's in mechanical engineering and robotics at Stanford in 2011. He built a Lunar Rover control device at NASA. He founded a drone company, Airphrame, ran it for about five years, and sold it to one of its own customers. By the time he turned to atoms, he had already learned the lesson he now repeats to anyone starting out: fall in love with the customer's problem, never the solution.

By The Numbers
$164M
Raised since 2019
20MWe
Per PWR-20 unit
800+
Podcast interviews
2026
Texas pilot target
Nothing has yet beat a 1968 nuclear power plant.
- Bret Kugelmass
The Playbook

Three industries, one reactor

Last Energy is a mash-up. Kugelmass borrows the engineering from nuclear, the construction discipline from oil and gas, and the money from renewables.

Borrowed physics

A pressurized water reactor, the most proven design on Earth. No new core, no new chemistry, no new materials. The conservatism is the strategy - it shortens the road to a license.

Factory modularity

Build the plant in pieces under a roof, the way shipyards and refineries do it, then assemble on site. Repeatable units instead of one-off megaprojects.

Renewable-style finance

Fund the build like infrastructure, with project finance covering construction and corporate capital covering licensing. Kill the interest bill, and the price of power falls.

The Arc

From lunar rovers to baseload power

2011
Earns a master's in mechanical engineering and robotics at Stanford. Works as a roboticist on a Lunar Rover control device at NASA.
2010s
Founds and runs Airphrame, an autonomous drone and aerial-imaging company, then sells it to one of its customers.
2017
Starts the Energy Impact Center in Washington, D.C., a nonprofit aimed at reversing climate change - and at finding the most scalable path to clean energy.
2018
Launches Titans of Nuclear. The first episode posts January 8 with guest Michael Shellenberger. The interviews become his research lab.
2019
Spins Last Energy out of the Energy Impact Center to commercialize small modular nuclear.
2024
Closes a $40M Series B. Named to the TIME100 Climate list.
2025
Announces the PWR-5 pilot with the Texas A&M University System at RELLIS, plans 30 microreactors in Haskell County, and closes an oversubscribed $100M Series C led by the Astera Institute.
2026
Targets mid-year to feed the Texas A&M campus grid. First full core load of fuel scheduled to arrive in September.
Capital

The money kept getting bigger

Last Energy funding rounds

Approximate, by round

Series A · 2020 (Gigafund)$20M
Series B · 2024$40M
Series C · Dec 2025 (Astera Institute)$100M

Series C proceeds aim at the PWR-5 pilot, PWR-20 commercialization, and Texas manufacturing.

Why Texas

Data centers got hungry

ERCOT, the grid that keeps Texas humming, expects electricity demand to climb 7 percent in 2025 and 14 percent in 2026 as data centers and heavy industry switch on. That is the kind of curve a 20-megawatt plant you can stamp out by the dozen was built for.

Last Energy's plan reads like a manufacturing roadmap, not a utility filing: a PWR-5 pilot at Texas A&M-RELLIS to prove the design, a target of powering the campus grid by mid-2026, then roughly 30 microreactors - about 600 megawatts - in Haskell County aimed at data-center customers near the Dallas-Fort Worth metroplex.

The Worldview

Nine words

His bio on X reportedly compresses the entire business plan into a line: likes robots, doesn't like climate change. It is glib, and it is exact. The robots built the engineer. The climate built the urgency. Last Energy is what happens when the two collide.

"Find a customer problem you want to solve. Don't become invested in a solution or a technology approach."

Watch

Kugelmass, unscripted

Unlocking Nuclear Power at Scale
Bret Kugelmass on the case for factory-built reactors
A Revisionist History of Nuclear Fear
Why, he argues, almost everything you fear about nuclear is wrong
Titans of Nuclear
The podcast that became his research lab - 800+ interviews
Off The Record

Things that don't fit a pitch deck

Before reactors

In high school he was the A/V kid and ran an amateur videography business. The microphone came back around.

The research came first

He recorded 800+ nuclear interviews before building a single reactor. The company is the conclusion of a very long podcast.

Old is the feature

He likes to say nothing has beaten a 1968 reactor. The PWR-20's throwback design is a selling point, not an apology.

Europe first

His earliest commercial targets were the UK, Poland, and Romania - countries readier to move fast than the slow-permitting US.

Three playbooks

Nuclear's physics, oil and gas's modular construction, renewables' project finance - stitched into one business model.

From NASA to nuclear

He helped build a Lunar Rover control device before he helped build power plants. The throughline is hard systems that have to work.

The Links

Follow the work

Last Energy LinkedIn X / Twitter Titans of Nuclear YouTube Talk Wikipedia: Last Energy

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