By now, the problem is clear:

• Peak U.S. electricity demand is expected to increase 5x from 2022 levels through 2029

While: 

• It takes an average of 10 years to build a new transmission project;
• Interconnection wait times have increased by 70% in the last 10 years; and 
• Nearly 2,600 GW of generation and storage capacity is stuck in the interconnection queue—more than twice the installed capacity of the existing U.S. power plant fleet

We can debate the specifics, but the broad strokes remain abundantly clear: we need to significantly expand our energy supply over the coming decade to support our most critical industries, fuel our economic growth, and sustain our technological edge. This was the basis of our Systems Power thesis, which has only become more timely over the last year. But as countries accelerate investments in AI, defense, healthcare, and the onshoring of supply chains, the marginal cost of energy has become all the more critical—a challenging reality for many emerging technologies that find it impossible to compete on price. 

Rather than feel discouraged by this reality, however, we are stimulated by its clarity and the opportunities it presents for a new generation of energy technologies. In our view, the companies that leverage current infrastructure and make existing fuel sources cleaner, more affordable, and more secure will become the generational winners in this energy transition. 

This was the core tenet of our investment thesis in Mainspring Energy, whose $258M Series F we are thrilled to have led, joined by many of the world’s leading energy investors: Amazon’s Climate Pledge Fund, DCVC, Temasek, Marunouchi Investment Partners, M&G, Pictet Private Equity and Mainspring’s longtime partners, Khosla Ventures, the Gates Frontier fund, Lightrock, and LGT Bank.

The Big Vision Behind a Pragmatic Solution

In our initial meeting with Mainspring’s co-founder and CEO, Shannon Miller, we were struck by the versatility and elegance of this technology—a software-defined, high-efficiency, non-combustion linear generator that can run on both conventional (natural gas, propane) and clean (hydrogen, ammonia, biogas) fuel sources. 

This fuel flexibility addresses a fundamental tension that has plagued clean energy for decades, eliminating the trade-off between clean, cost-effective, and readily available solutions. The system’s ability to leverage natural gas for baseload power but make it cleaner and more efficient provides a pragmatic, win-win for customers who need power now and was one of the driving theses behind our investment. 

Mainspring’s ability to address a range of energy needs, most notably, speed-to-power, sustainability, cost savings, and resiliency, is driving commercial adoption across a variety of customer types, including data centers, EV microgrids, C&I, and even large utilities; each of which faces unique challenges depending on their power requirements, commitment to low-emission technologies, and the local regulatory and market structures in which their sites operate. In such a rapidly evolving energy landscape, these customers want flexible, distributed technologies like Mainspring that can adapt with them and facilitate a more affordable and achievable clean energy transition. And this isn’t theoretical whimsy. With several years, and hundreds of MW of power in field operations and advanced development projects, Mainspring is solving these customer pain points today and using the capital from this round to expand its existing production capacity and scale its commercial impact.

Beyond the value proposition of the technology itself, the technical acumen and passion of the founding team, and their commitment to building a practical, solution-oriented technology with deep customer empathy, have prepared Mainspring to capitalize on this tremendous market opportunity and make us so privileged to support them on this mission. 

Leveraging World-Class Operators to Expand Possibilities 

At GC, we believe that experienced operators are invaluable assets to founders and executives trying to scale new technologies in complex and regulated markets and seek to incorporate such individuals in our energy investments (refer to our investment in Fever as another example of this approach).

As such, we are thrilled to announce that Tom Linebarger, the former Chairman and CEO of Cummins, is joining Mainspring’s Board of Directors. Over his 30 years at Cummins, Tom ran several business lines, including Power Generation, and scaled Cummins from approximately $17B to $28B in revenue and doubled the company’s market cap in his time as CEO. When we first introduced Tom to Mainspring, he quickly recognized what a unique solution it was for solving today’s most pressing energy needs and was impressed by the sophistication of Shannon’s leadership, engineering, and supply chain teams. 

As Mainspring scales production and expands its commercial impact to meet this moment, Tom’s counsel will be invaluable to realizing the full potential of this technology and building a truly generational company in this space.

Given the challenges we face in energy today, we can no longer rest on the hope that patience, non-dilutive capital, and compromise will create energy resilience. It’s time for us all to become energy pragmatists and we couldn’t be more excited to support Mainspring on its journey.