Crusoe, a Denver-based AI data center startup that recently raised $3.9 billion, has ended plans to use a new line of stationary power plants developed by fellow Denver company Boom Supersonic.

Founded in 2018 as a bitcoin miner that ran on excess natural gas from oil fields, Crusoe has since become one of the biggest builders of AI data centers, including a massive campus in Abilene, Texas, that supplies computing power to OpenAI.

Boom Supersonic, which is developing a supersonic passenger jet called Overture, launched a new business last year to sell a version of the engine it’s developing for that jet as natural gas-fired stationary power plants. Its Superpower turbine shares about 80% of the same parts with that airborne engine, called Symphony.

Crusoe had signed on to be the first customer for this business, agreeing to spend $1.25 billion on 29 of Boom’s 42-megawatt Superpower turbines. The first deliveries were supposed to begin in 2027. But that deal has since fallen apart, according to Boom Supersonic CEO Blake Scholl.

Friday, in a post on X, after congratulating Crusoe founders Cully Cavness and Chase Lochmiller on the company’s recent raise, Scholl said the companies are no longer moving forward with the turbine launch partnership. Although he did note that other customers were in its pipeline.

“The TL/DR is that turbines are no longer part of Crusoe’s near term primary power mix at Abilene/etc., so a launch partnership just didn’t make sense,” he wrote in the post. “Boom will be delivering about 250MW of Superpowers next year to other sites, and we’re targeting 1GW in 2028. We’re grateful for the help Crusoe gave us in shaping Superpower and continue cheering for their successes. The future is long, and we look forward to potentially teaming up if/when turbines become part of their primary power mix.”

Crusoe confirmed to TechCrunch that it is no longer doing business with Boom.

“We build AI factories from the power up, and we’re bringing new campuses online across the country, powered by innovative energy sources,” spokesperson Andrew Schmitt said in an email. “As our portfolio grows, we stay flexible, choosing the energy solutions that are right for each site as its needs evolve – including turbines, along with wind, solar, batteries and the grid. While Boom has been a great partner, the partnership isn’t the right fit today. We wish them well.”

Crusoe’s initial 1.2 gigawatt data center in Abilene that was built for Oracle and OpenAI is powered by the grid, according to the company. There is also a gas-turbine power plant that is used for backup power only. Crusoe is also building a 900 megawatt data center in Abilene for Microsoft, which will be powered on-site gas turbines.

Losing its launch customer is seemingly a setback for Boom, which raised $300 million last year, largely to commercialize the new business. The idea, Scholl told TechCrunch at the time, was to use profits from the stationary power plant business to fund the development of Overture.

Scholl could not be reached for comment before publication; TechCrunch will update this article if he responds.