Elon Musk acquired APR Energy earlier this year, adding a new business to his portfolio: fossil fuels. APR produces mobile gas and diesel turbines that can be mounted on trailers. The move happened quietly in May, with no public announcement or declarations from Musk or APR itself. Electrek only picked up on the filing yesterday, and it estimates the purchase value at about $1 billion.

The most likely application for this purchase will be powering AI data centers. Producing all that NSFW content demands a whole lot of energy. APR’s mobile fleet is similar to the turbines Musk’s xAI was sued for using at a data center in Southaven, Mississippi on charges of violating the Clean Air Act. Since that suit was filed, the number of mobile turbines at the data center has increased significantly. The Department of Justice is attempting to have the suit dismissed so that the US military can keep using xAI’s Grok for its operations.

Investing in gas and diesel marks quite a reversal from the game Musk was talking a decade ago, when he called continued use of fossil fuels “the dumbest experiment in history, by far.” His business may further compound that experiment by building a natural gas pipeline in Texas.