The Green Blueprint

A complex path for building heat batteries

The Green Blueprint

Show Notes

In 2022, John O’Donnell and Peter von Behrens figured out how to design a heat battery that would deliver heat at very high, constant temperatures. The breakthrough came on the heels of two years of research and development, some of which took place in Peter’s garage. Now, John and Peter were ready to prove their technology at commercial scale. So they approached a long-time innovation partner, Calgren Renewable Fuels, about deploying a 2-megawatt-hour heat battery for industrial heat delivery in Calgren’s Pixley, California plant. That’s when the next wave of problem solving started. It turns out, designing the technology was just half the battle. Manufacturing and installing a commercial scale demonstration proved harder than expected. In October 2023, they started on a six-month construction project that threw a myriad of challenges at the new start-up. In this episode, Lara Pierpoint talks to John O’Donnell, co-founder and chief innovation officer at Rondo Energy, about the bumpy road of building a first-of-a-kind commercial demonstration. They cover things like the structural engineering challenges of scaling a new technology, and finding the right construction partner. Plus, John explains what new design specs mean for the company going forward. The Green Blueprint is a co-production of Latitude Media and Trellis Climate. Subscribe on Apple, Spotify, or anywhere you get podcasts. For more reporting on the companies featured in this podcast, subscribe to Latitude Media’s newsletter.

More from The Green Blueprint

Oct 21, 2026

This week, we’re presenting a drop-in episode of Critical Capital, a new partner podcast from Crux and Latitude Studios.

Oct 7, 2026

While living in Delhi, Sorin Grama gave a window air conditioner to an employee. He found out weeks later she wasn't using it because the electricity costs were too high. It was a stark reminder that access to global cooling isn't about upfront equipment costs. It’s about the high electricity costs needed to run air conditioners.

Sep 23, 2026

When David Fauvre and his co-founder entered the battery space in 2015, they started as brokers exporting American battery waste to recycling partners in Korea and Japan. But as the industry grew, shipping companies increasingly refused to transport the hazardous materials, making it clear that the U.S. desperately needed its own domestic processing capabilities.

Sep 9, 2026

“Good fires" naturally regenerate forests. But a rise in high-severity blazes in the American West are leaving behind barren moonscapes filled with dead trees. These scorched trees act as hazardous fuel for future fires, but clearing them to replant the landscape is astronomically expensive. Add to that a massive shortage in the conifer seed supply chain, and land managers simply don't have the resources to regenerate these forests on their own.

Aug 26, 2026

To build the physical infrastructure of the clean energy transition — from wind turbines and grid stabilization to massive new AI data centers — the world needs more copper between now and 2050 than humanity has produced in its entire history. But new copper mines take anywhere from 10 to 16 years to permit and build, meaning we’re not on track to meet our rapidly growing demand.

See all episodes →