TerraPower's molten salt reactor uses thermal storage to match AI data center power swings

TerraPower, the nuclear startup founded by Bill Gates, is preparing to announce its first data center project this year, joining a growing cohort of companies pitching nuclear power as a solution to the relentless demand from AI facilities. The company previously secured a major commitment from Meta to purchase eight of its Natrium reactors, and its inaugural power plant is already under construction in Wyoming.

Why nuclear alone isn't enough for AI#

Unlike traditional industrial loads that remain relatively stable, AI data centers present an unusual problem: their power consumption fluctuates dramatically as GPUs tackle varying computational tasks. Natural gas turbines have even experienced physical stress from these sharp swings. Most nuclear plants are engineered to run constantly at peak output—achieving around 92.5% capacity factors in the U.S.—because they're expensive to build and slow to adjust. Ramping output up or down takes time, and existing reactors can only shift about 5% of their rated capacity per minute.

The economic math becomes unforgiving quickly: if a plant isn't generating electricity, it's hemorrhaging money. Data centers with on-site power need the plant to remain productive even during demand valleys, yet must accommodate sudden spikes without turning to expensive battery banks.

TerraPower's thermal storage advantage#

TerraPower's 345-megawatt molten salt reactor solves this mismatch through a clever thermodynamic trick. Rather than throttling the nuclear reaction itself—an inflexible process—the reactor maintains continuous fission while channeling excess heat into massive reservoirs of molten sodium. When demand surges, the plant taps that thermal energy to generate additional steam and power without pausing nuclear operations.

The design was originally conceived to handle the variability of wind and solar resources on power grids, but the same principle applies to AI workloads. The molten salt acts as a buffer, keeping the reactor's expensive capital equipment in near-constant use and allowing TerraPower to spread its substantial upfront costs across more productive hours.

A potential competitive edge#

This approach combines nuclear power's defining strength—reliability and high output—with energy storage flexibility that competitors pursuing smaller modular reactors (SMRs) lack. While SMRs can ramp faster than traditional reactors (about 10% per minute), they still can't match the dispatch flexibility that molten salt thermal storage enables. For the nuclear startup ecosystem racing to make early projects economically viable, avoiding the need for massive battery installations could prove decisive.