The installation is housed in what looks like a four-story prefabricated office building. Inside sits a massive stack of refractory bricks, which are heated to temperatures of more than 1,000 degrees Celsius (1,832 degrees Fahrenheit) by an adjoining 20-megawatt solar array. That heat is tapped to generate steam that is injected into oil wells to increase production — a job previously done by a fossil-gas-fired boiler.

The project is something of a Faustian bargain. It will reduce carbon dioxide emissions by about 13,000 metric tons per year, said John O’Donnell, Rondo’s cofounder and chief innovation officer. But, of course, those reductions are in service of bringing more planet-warming fossil fuels to market.