"Brick toaster" aims to cut global CO2 output by 15% in 15 years. Seriously.

A quarter of humanity's carbon emissions come from industrial energy use – and a huge portion of that energy goes into creating heat for various .
A quarter of humanity's carbon emissions come from industrial energy use – and a huge portion of that energy goes into creating heat for various processes. And right there lies a slam-dunk decarbonization opportunity that'll pay for itself incredibly quickly, reasons Oakland company Rondo Energy.
"We're at a spectacular moment in history," Rondo CEO John O'Donnell told the Wharton Current podcast. "Where on a per unit of energy cost basis, wind and solar power are cheaper than fuels. Not just cheaper than conventional electricity, but cheaper than fuel for heat in most of the world – headed for all of the world."
In other words, thanks to a huge crash in the price of renewable energy, there's no longer a "green premium" stopping most industrial heat consumers from decarbonizing and switching to clean solutions. The barrier, instead, is intermittency; you can buy renewable energy out of the grid at extremely low cost, right now – but only when the solar arrays are producing too much for the grid to use. You can't run your factory 24/7 that way unless you can store that energy up.
And here's Rondo's play: this company is building "brick toasters" that store up cheap renewable energy as high-temperature heat, ready to be deployed throughout the day – and it says industrial clients will begin saving money compared to their old, dirty, fossil-fuel burning processes immediately.
At the heart of it, this ain't rocket surgery; converting electricity into heat is something that happens at 100% efficiency every time you turn on your toaster or hairdryer, says O'Donnell. Rondo uses a simple toaster-style system to heat up "blast stoves," similar to the ones the steel industry already uses for cyclical heat storage. These stoves are full of plain ol' bricks, made out of plain ol' clay, sometimes with a bit of sand in there, but certainly nothing special in terms of materials. Nothing toxic, nothing that decays over time. These bricks will still be storing heat just as well in 40 or 50 years' time, when chemical batteries have gone through several generations of complex recycling.
Rondo says it can pull that heat back out at an extraordinary 98% efficiency, resulting in a dirt-cheap industrial heat storage solution that costs "about one fifth the cost per unit of energy stored as any electrochemical battery," according to O'Donnell. "On the outside, it looks fairly boring. It's only possible today because of supercomputer computational fluid dynamics, and finite element analysis and AI system controls. We're building something that's very simple – but was very interesting and complicated to design."
The first generation of Rondo brick toasters are optimized for low cost, super-fast deployment and scale, and are capable of holding heat up to 1,500 °C (2,732 °F), which O'Donnell says can cover approximately 80% of industrial heat requirements globally. Down the track, using more expensive heaters and brick materials chosen for the purpose, he says it's possible to hit 1,800 °C (3,272 °F) or so, which brings steelmaking into range, and would cover somewhere around 92% of industrial use cases.
"The couple of years of science and investigation are behind us, and we are right now making the journey from the labs, through late-stage prototypes, to our first customer installations this year with a goal of being at very large scale next year in the year beyond," said O'Donnell. "And we're looking very hard at the project finance community and the pathways that enable scaling the fastest."
Rondo's first customers, he says, have zero interest in being "green" or advertising their decision. They're in this for the bottom line, taking advantage of the arbitrage opportunity that intermittent clean energy presents. And right now, it's a hell of an arbitrage opportunity. "Today, electricity through a Rondo u...