Mainspring Energy, the Stanford spin-out building fuel-agnostic generators, will bring its first artificial intelligence data center online this summer. The large project is designed to scale up to hundreds of megawatts in total generator capacity — and is also the company’s first full-scale commercial deployment with a greenfield data center site.
It’s a critical growth point for Mainspring, and comes at a time when the energy sector and the wider economy are experiencing federally-induced turbulence. In April, the company raised a $258 million Series F led by General Catalyst. However, the company’s $87-million grant from the Department of Energy is now in limbo; if and when it will be disbursed remains unclear.
The central Mainspring value proposition for data centers is that their fuel-agnostic systems can replace diesel generators as backup power, offering a simpler and lower-cost path to “five nines” reliability, plus flexibility to run on any type of gaseous fuel. Most Mainspring generators currently run on fossil gas or biogas.
Over the course of the last year, however, as the company’s data center pipeline has grown, Mainspring has positioned itself not only as a lower-emissions alternative, but as a solution for capacity and transmission bottlenecks. According to CEO Shannon Miller, speed to power is quickly becoming a priority for developers.
“Cost, reliability and sustainability have always been the three big things that everyone cares about, but now speed has become a bigger and bigger part of everyone’s design process, because the grid’s not moving fast enough,” CEO Shannon Miller explained.
“People do want to be connected to the grid, but they see these microgrids as ways to move more quickly, and that’s a place where we can really help them,” she added, pointing to the increasingly long wait times for gas turbines. It’s a service that diesel generators, which are generally designed to run no more than 200 hours a year, can’t provide.
Mainspring completed an integration of its generators with its first data center partner last fall. That was a “good initial proof point” to show other data center customers that the system can integrate smoothly with existing infrastructure, Miller said; that project wasn’t much different from Mainspring’s work with commercial and industrial customers, she added. That customer has now moved on to integrating generators at a larger facility.
But the process of powering the upcoming AI-specific data center, whose location and customer Miller declined to share, is a little different, she said. For one thing, the time to ramp up has been significantly faster. For another, the data center will initially be islanded, running only on Mainspring generators when it comes online, without any diesel generators.
“Most data centers still have diesel backups, and so this will be a new paradigm,” Miller explained. “It’s a simpler and lower cost design, but it’s definitely a new setup.
That data center, she added, will be scaled up modularly, in 25- to 50-megawatt increments, and will start to come online later this summer.
Barriers to scale
Mainspring’s recent Series F Mainspring was largely to help the company scale up its manufacturing in order to meet growing demand. That includes building a $175 million manufacturing facility in Pittsburgh, large enough to produce up to 1,000 generators annually. Once constructed, the factory will create more than 600 jobs in the region in fields like metalworking, machining, and production.
So far, the company has largely avoided any “massive impacts” to its supply chain due to the shifting tariff landscape, Miller said, though she acknowledged that “it’s a moving target.”
The bigger question mark, at least as far as the future of the Pittsburgh factory goes, is the state of a federal award Mainspring won late last year. In October, DOE’s Office of Manufacturing and Energy Supply Chains tapped Mainspring for an $87 million grant, under the Bipartisan Infrastructure Law’s Advanced Energy Manufacturing and Recycling Grants program. That funding was slated to help Mainspring break ground on the Pittsburgh factory later this year.
But Miller said the company hasn’t had any contact with DOE since the inauguration; and the silence has forced the company to develop contingency plans. “We’re working through a number of different scenarios,” she explained, for “if the grant takes a lot longer or doesn’t come through for some reason.” Those include trying to increase efficiency and capacity at Mainspring’s existing facilities, or else pursue a slower ramp up in Pittsburgh that would allow the company to “sort of pay as we go, as opposed to doing a bigger investment up front.”
For domestic development more broadly, Miller added, the fate of the IRA tax credits will likely affect how quickly the company’s growth takes off. Mainspring is paying particularly close attention to the fate of the 45V hydrogen credits, for example, and has had several customers looking to run green hydrogen pilots with the generators.
(The hydrogen tax credit was targeted in the first draft of budget cuts proposed by the House this week. Under that proposal, the credit would be terminated for any projects not already under construction by the end of the year.)
As far as international expansion, Miller said the company is hearing feedback from data center developers in places like Europe, the Asia Pacific, and the Middle East, that they’re also interested in Mainspring’s technology.
“We are starting to look at some of those locations, but we haven’t installed anything outside of the U.S. yet,” she explained.
