A grassy plain in Nevada’s Humboldt County is where the contest between the U.S. and China for mastery of the global economy could be won or lost. Called Thacker Pass, the empty patch of land, 230 miles from Reno, looks decidedly uninteresting, home to little more than scrubby bushes. But it’s what lies beneath that places the site at the center of the twenty-first century economy: Lithium. That once-obscure metal, long suffering in the shadow of copper, iron ore and other widely cherished commodities, has now claimed the global spotlight. The challenge of climate change has elevated lithium into the indispensable ingredient for the green energy age. As all the world’s major economies push aggressively to electrify their transportation, lithium — and the batteries made with it — will power that revolution.  But here’s the problem: There won’t be enough lithium to go around, at least in the near term. The U.S., for instance, produces hardly any — less than