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Mainspring's linear generator. Photo courtesy of Mainspring.

The distributed generation company Mainspring Energy has raised $95 million in new funding led by Fidelity Investment's private equity arm, alongside other new and existing backers like Chevron, Princeville Capital and Bill Gates.

Why it matters: There's growing interest in low-carbon onsite power sources as a way to fight climate change and to create more flexibility and resilience as grids are increasingly stressed by extreme weather.

How it works: The Bay Area firm's technology, called a "linear generator," is designed to run on multiple fuels.

  • It uses a "low-temperature reaction of air and fuel to drive magnets through copper coils to efficiently produce electricity."
  • CEO Shannon Miller has likened it to "an air hockey table that you’ve wrapped around into a tube."

Where it stands: Mainspring — founded by Stanford engineers in 2010 and formerly called EtaGen — said the new money brings its total capital raised to $228 million.

  • The Series D financing will enable Mainspring to add customer deployments, expand manufacturing and add staff, the company said.
  • It comes about two months after Mainspring announced a $150 million deal with power heavyweight NextEra Energy Resources to buy Mainspring units and finance customer projects.

Go deeper: Clean energy patenting is outpacing fossil fuels, but experts warn it's not enough

Go deeper

California energy commission mandates solar panels for new buildings

A person carrying a solar panel into a home in a home in Alamo, California, in May 2017. Photo: Scott Strazzante/San Francisco Chronicle via Getty Images

The California Energy Commission voted Wednesday to require solar panels and battery energy storage systems in new commercial buildings and certain multifamily residences beginning in 2023, according to the New York Times.

Why it matters: It's an aggressive step in California's transition away from fossil fuels and broader drive to cut carbon emissions, although the provision must first be approved by the state's Building Standards Commission.

Stephen Breyer formally announces retirement from Supreme Court

Photo: Andrew Harnik/AP

Justice Stephen Breyer on Thursday sent a letter to President Biden formally announcing his retirement from the Supreme Court.

State of play: Breyer said his retirement will take effect when the court "rises for the summer recess (typically late June or early July) assuming that by then my successor has been nominated and confirmed."

COVID created an epic U.S. trade gap

Chart: Axios Visuals. Data: Census Bureau/Bureau of Economic Analysis

The details of the blockbuster fourth quarter GDP report released Thursday morning tell a vivid story of how the underpinnings of the world economy have been reshaped by the pandemic.

One example: In the arithmetic around U.S. economic output, trade acted as a more severe drag last year than it has in a generation.