(Reuters) - Elon Musk's AI startup, xAI, is facing criticism from environmental and health advocates for allegedly contributing to pollution in Memphis, Tennessee, by using natural gas-burning turbines at its data center without obtaining necessary permits.

The Southern Environmental Law Center sent a letter to the Environmental Protection Agency and the health department in Shelby County where the data center is located.

"Despite installing nearly 20 gas turbines with a combined capacity of about 100 MW - enough electricity to power around 50,000 homes - xAI apparently has not applied for any air permits for these turbines," the letter, dated Aug. 26, said.

The environmental legal advocacy organization called on the county's health department to verify if xAI is operating these turbines without the required air permits and take enforcement action.

It said the gas turbines emit large quantities of gases that exacerbate already poor air quality in Memphis.

Musk said late last month a cluster of powerful Nvidia H100 chips started training xAI's Grok AI model and dubbed the Tennessee data center as "the most powerful AI training cluster in the world".

He added the facility will provide a significant advantage in training the world's most powerful AI by December.

Elon Musk and xAI did not immediately respond to requests for comment.

The startup, founded by Musk last year and valued at more than $24 billion in May, was billed as a competitor to OpenAI, Alphabet's Google and Anthropic. It recently launched Grok 2 series of language models earlier this month.