Here’s how they unintentionally founded North America’s largest climatetech incubator

Promethean Power Systems needed to find new prototyping space after one of its founders, Sorin Grama, graduated from MIT, eventually locating a warehouse on Cambridge’s Charles Street. They teamed up with three other startups in 2011, all of which had founders who’d graduated from MIT and seen firsthand how out-of-reach lab space can be for new companies.

As news spread about the warehouse, more climatetech companies joined the ragtag group of startups. Promethean co-founder Sam White describes the group as “a hodgepodge of nomads” who would trade technical tips and work alongside each other late into the night.

When Jason Hanna, the co-founder of Coincident, spent a significant amount of time helping Promethean edit a grant proposal, White “realized something special was going on.”

Soon, the spirit of collaboration spread to every facet of entrepreneurship. From sharing equipment to swapping staff to lending emotional support, the climatetech startups that banded together were benefiting far beyond a smaller rent check.

“We would bring in investors, and they couldn’t just come in and see us, because everyone was in the hallways—we’d say, ‘Here’s this company, here’s that company,’” White explains. “When we had technical hurdles, we would lend engineers to help with a problem. Some of the technical breakthroughs happened because of the collaboration among us.”

The benefits of that collaboration carried the unforeseen incubator from the Cambridge warehouse to Boston’s Fort Point neighborhood—which was just then being dubbed the “Innovation District” by Boston’s late Mayor Thomas Menino—to Somerville’s Union Square. The number of companies jumped from four to 17 to 25 to 55 in a few short years. Greentown expanded to another building in December 2017, and the 100,000-square-foot campus now offers prototyping and wet lab space, shared office space, a machine shop, a tool shop, and an electronics lab.

In Spring 2021, Greentown Houston—Greentown’s first out-of-state expansion—opened with the intention of accelerating the energy transition in the energy capital of the world. This 40,000-square-foot incubator, located in the Innovation District being developed by Rice Management Company, offers prototyping lab, office, and community space.

Today, Greentown offers more than 200 startups in Somerville, Houston, and globally the expertise, resources, and support they need to change the world. Whether that involves introductions to strategic partners or high-end equipment or the community itself, Greentown has now buoyed hundreds of cutting-edge startups that are tackling climate change head on.

The Founding Four