It’s All Coming Together

By Katie Rae, CEO & Managing Partner of The Engine

In early 2018, the Commonwealth Fusion Systems team was hard at work planning its fusion machine just steps from my desk. Three years later I was standing in a control room amongst fusion engineers at the MIT Plasma Science Fusion Center as CFS successfully tested a magnet that can contain the same reaction that powers the stars. That test proved to the world that commercial fusion energy can — and will — reach the grid in the next decade. The company’s $1.8B Series B underscores the incredible confidence that CFS will be the company to make that future a reality.

It’s been one of my great privileges to support Bob Mumgaard, the CEO and Co-Founder of CFS — as well as the entire CFS leadership team. As a first-check investor and board member since the beginning, I’ve seen their unyielding dedication to creating a better future, one in which fusion power plants provide us all with limitless, zero-carbon energy. Bob’s optimism as a founder is backed by a lifetime of dedication to the science behind this fusion-powered future. He’s so modest, however, that it’s easy to forget how monumental his company’s achievements are.

The Commonwealth Fusion Systems founding team (L-R): Zach Hartwig, Brandon Sorbom, Martin Greenwald, Dennis Whyte, Bob Mumgaard, Dan Brunner

I shared the following with The Engine’s team and network after September’s successful magnet demonstration:

Imagine completely eliminating the need for power plants fueled by coal or gas. Truly zero-emissions energy, with zero harmful waste, forever. I hesitate to use an expression so common in VC circles that it’s beginning to lose any meaning, but in the case of CFS, it has never been so true — this technology will change the world.

Bob and his team are working with the U.S. government and major private utility companies to set the stage for grid-scale commercial fusion energy. On November 17, Bob, along with other leaders in fusion research and development, testified before the U.S. House of Representatives Committee on Science, Space, & Technology. They spoke with authority and optimism about how the U.S. can be the first country to achieve net-energy fusion and how such an achievement can bolster both our nation’s economy and security.

As Bob noted in his testimony: We need only to look at the impressive track record of establishing new industry sectors such as space, biotech, and others to know that the U.S. can lead in bringing fusion energy to the world by combining the American entrepreneurial spirit, robust capital markets, and full life cycle R&D investment of the private sector with the right support from the U.S. government.

A rendering of SPARC, the world’s first fusion device that will produce plasmas that generate more energy than they consume. This compact, high-field tokamak will be built with HTS magnets, allowing for a smaller device than previous magnet technology.

CFS is scaling with purpose and speed, recruiting engineers from across the globe to help it build its first net-energy tokamak (dubbed SPARC) — the team has grown from a dozen when we first invested in 2018, to over 200 today. And construction has started on the team’s new headquarters in Devens, MA, where, quite literally, the foundations of a fusion-powered future are being poured.

A rendering of the CFS campus in Devens, MA. Image courtesy of CFS.

Robust capital markets, significant private sector interest (an understatement), and funding from the U.S. Department of Energy are massive tailwinds for CFS. It’s thrilling to watch the team receive such support. And I look forward to continuing to serve on their board during what will undoubtedly be transformative years.

The magnitude of the CFS Series B raise not only shows us how much faith we all have in the team’s ability but also the strength and global relevance of the Tough Tech investment landscape in general.

Our recent Tough Tech Landscape report explores the investment numbers behind the past record-breaking years. More importantly, however, the trends are qualified by what we’re seeing every day at The Engine — exceptional individuals making the jump to Tough Tech entrepreneurship and, simultaneously, growing interest from a broader array of stakeholders, including corporate partners, government officials, and other partners across the capital stack.

We are not alone in witnessing this positive momentum. Friends throughout Boston, The Engine investment community, and others are all experiencing similar levels of enthusiasm from founders and partners. And that enthusiasm, brought to life in this latest round of investment for CFS, is something that should give us all hope for a healthier, happier, and more extraordinary future.

Companies like CFS are a rare thing and leaders like Bob are even less common. I’ve worked with hundreds of startups in my career and CFS stands out for its unique combination of technical skill and devoted sense of purpose. None of us could have predicted just how quickly the team would achieve such a monumental milestone — and none of us can predict where a fusion-powered future will take us. But there is one certainty: when CFS succeeds at harnessing the power of the stars, it will change the planet overnight. If today’s announcement is any indication, such success is all but inevitable.




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The Engine

The Engine

Built by MIT, we help founders create the next generation of world-changing companies. Visit us at

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