By Ernest Scheyder (Reuters) -In a February meeting with mining executives, President Joe Biden laid out an aggressive goal for the United States to produce more of its own minerals for the electric vehicle revolution in ways that respected the environment. A “big part” of those efforts, the president said, was a plan by Warren Buffett’s Berkshire Hathaway Inc to filter lithium from superhot geothermal brines swirling beneath California’s Salton Sea, something that had never been done before. The project aimed to help usher in a new way of producing lithium – a key constituent of EV batteries …