We’re back on the road this week, to California’s Salton Sea, a salty lake in the desert that was once marketed as “Palm Springs with water.” Today the water is receding and increasingly toxic. The community that once thrived here now has one of the highest unemployment rates in the country. 

But there is some hope. There’s a huge amount of lithium all around the Salton Sea in the bubbling hot brine deep underground. Some hopeful modern-day 49ers have big plans to get it out. If they can only succeed, the lithium here could meet 40 percent of the world’s demand.