Deals Counterparts

Jane Street participates in $35 million Series B funding for energy storage company Mainspring Energy

Investment Energy Storage announced Menlo Park, United States Sep 28, 2025
USD95M
Deal Value
250 kW
Capacity
operating
Stage

Mainspring Energy, an energy storage company, secured $35 million in Series B funding with participation from Jane Street, Lightrock, and Bill Gates. The funding will support the scaling of its linear generator technology.

Source Intelligence

KEY DETAILS

The round brings the Menlo Park, Calif.-based startup’s total funding to $ 228 million. and it has a $ 150 million contract with NextEra Energy to finance more deployments across the country.

Deal Size
On Tuesday, Mainspring raised a $ 95 million Series D investment to put that premise to the test.
Capacity
Mainspring’s 250 -kilowatt units capture the motion of two oscillators moving back and forth in an air-cushioned housing.
Location
The round brings the Menlo Park, Calif.-based startup’s total funding to $ 228 million.
Announcement
By Jeff St. John 4 May 2021
PARTIES MENTIONED IN SOURCE
M
Mainspring Energy developer

"Mainspring Energy raises $ 95 M for linear generators to clean up the grid"

D
Devonshire Investors investor

"The round was led by Devonshire Investors, the private equity firm affiliated with Fidelity Investments parent company FMR LLC"

P
Princeville Capital investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

4
40 North Ventures investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

C
Chevron Technology Ventures investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

K
Khosla Ventures investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

B
Bill Gates investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

C
ClearSky investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

A
AEP investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

K
KCK investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

E
Equinor investor

"adds new investors including Princeville Capital, 40 North Ventures and Chevron Technology Ventures to existing investors Khosla Ventures, Bill Gates, ClearSky, AEP , KCK and Equinor."

N
NextEra Energy buyer

"and it has a $ 150 million contract with NextEra Energy to finance more deployments across the country."

N
NextEra Energy Resources partner

"Mainspring’s partnership with NextEra Energy Resources, the business services arm of the Florida-based utility and renewables behemoth, is based on a similar energy-as-a-service approach as many of the above-mentioned offerings, bundling backup and always-on power into power-purchase agreement structures that allow customers to pay back installation costs over time."

high quality Enriched Feb 19, 2026

Timeline

Announced
Sep 28, 2025
Signed
Closed

Market Context

This deal is part of the Energy Storage sector in United States.
13
Energy Storage deals
565
deals in United States
1 of 13 Energy Storage deals tracked this month · Updated daily

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