'Linear' Gas Generation Adds Flexibility for Big US Power Users

This article was originally published by Energy Intelligence Group on April 2, 2026. 

Natural gas is typically touted for its versatility in generating electricity. But one US company is pushing the limits with its modular, flex-fuel generators that are attracting large-scale customers like Amazon and the US Air Force. 

"Linear generators" — developed by California-based Mainspring Energy — can interchangeably use either methane-based gases, such as drilled natural gas, landfill gas and biogas, or gas derivatives like hydrogen, syngas, ammonia, and propane.

This fuel-switching flexibility's primary advantage comes when the primary generation fuel — most likely natural gas — is disrupted by a weather event, explosion, cyber attack or other incident. That's one reason the company insists linear generators are an ideal baseload power source.

"Basically, when you bring in a different type of fuel, we just compress more or less, depending on the chemistry and thermodynamics of that fuel," Mainspring cofounder and Chief Commercial Officer Adam Simpson told Energy Intelligence.

Powering Data Centers

In the process, the linear generators do not require water or emit nitrogen oxides, Simpson explained. Concerns about such emissions have triggered grassroots resistance to facilities that use conventional gas turbines or generators — notably artificial intelligence data centers.

Mainspring's technology involves 250 kilowatt units that can be combined to increase capacity to essentially whatever is needed. That's an attribute Simpson characterizes as critical at a time when electric companies and large-scale power customers are seeking ways to swiftly meet soaring demand.

The Utah Municipal Power Agency, for example, is now using a 48 megawatt system on its distribution network.

"We will soon ... announce a 35 MW project with another electric cooperative, and we're also seeing traction in the data center space," Simpson said. "We have our first project with [data center operator] EdgeConneX that's operational, and we're looking at powering more data centers this year."

Grocery giant Kroger has deployed linear generators as a behind-the-meter power solution, and Amazon is moving forward with linear generators for "last-mile" sorting facilities and electric vehicle charging. "We have a big microgrid coming on line with Amazon," Simpson said.

Military Momentum

Potential US military customers are looking seriously into Mainspring's linear generators — notably the US Air Force — as part of a broader effort to power installations with flexible energy options.

Linear generators are "a highly mission resilient and mission flexible resource," said Kirk Phillips, head of the Air Force Office of Energy Assurance, in an interview with Energy Intelligence.

In addition to their adaptability to unexpected fuel disruptions, linear generators "appear to have a much lower maintenance requirement and training requirements" compared to other energy options, Phillips added.

Because linear generators are modular, they could be placed at different locations around a base and thus reduce exposure to disruptions at any one location. The Air Force is seeking more details from Mainspring on how durable and long-lasting the generators are as a main power source.

Broadly speaking, Air Force planners rate linear gas generators highly in terms of desirable attributes, alongside geothermal and nuclear power, Phillips said.

His office considers five "R's" when evaluating energy choices for installations: reliability, which minimizes points of failure; resilience, which is the ability to nimbly recover from disruption; redundancy, in which backup energy supplies are available if main sources fail; responsibility, which refers to environmental stewardship; and resource availability, which refers to ease of access.

Chasing Versatility

Mainspring originated from doctoral research at Stanford University and was founded in 2010, which kicked off a decade of research and development before it began offering its 250 kW commercial product in 2020.

"The linear generator has the efficiency and emissions benefits of fuel cells, but the robustness and dispatch ability of engines and turbines," Simpson said.

Mainspring says the system was designed from the start to be highly flexible. "You can right-size the number of units for any power needs, and high-efficiency fuel flexibility. We can turn off and on, ramp our power up and down," Simpson said.

Mainspring considers its system the forerunner in the linear generator field, but Texas-based Hyliion is deploying a similar technology developed by General Electric that can also run interchangeably on natural gas, hydrogen and other gases.

Data center designer Flexnode began integrating Hyliion linear generators at data complexes last year, and Hyliion is also in talks with other customers, including military users.