Stored in a building the size of 13 football fields, a supercomputer built to propel Elon Musk’s artificial-intelligence enterprise dubbed xAI has flipped the “on” switch in South Memphis, Tennessee. But residents, environmental agencies, and some City Council members say they didn’t know it was coming. “We have been deemed by xAI not even valuable enough to have a conversation with,” KeShaun Pearson, president of the nonprofit Memphis Community Against Pollution, tells NPR. Memphis Councilwoman Yolanda Cooper-Sutton says she found out about the plant watching the news. It seems that the mayor…