Amid a shortage in natural gas-fired turbines to generate electricity, a Missouri-based company is making them out of repurposed jet engines.

Energy solutions firm ProEnergy has sold at least 21 retooled turbines for two data center projects, the company’s vice president said at a conference in October, according to engineering magazine IEEE Spectrum.

A global shortage in gas turbines has meant that companies must wait years for new turbines to be delivered. This has led to an interest in alternatives, especially by developers racing to build new data centers for AI.

On Wednesday, the U.S. Energy Information Administration estimated that thousands of retired aircraft sitting at an Air Force base in Arizona could be reuse to generate power. The agency estimates that the site, known as the Boneyard, could combined generate up to 40,000 megawatts of electricity, 10 percent more than all of the power plants in Arizona running at full capacity.