When oil is cheap and seemingly limitless, the inefficiency of the gasoline engine is acceptable. But oil is no longer cheap, and it's not limitless.
Not all of these elements are rare, but none are as abundant as the dominant raw materials of 20th-century industry: iron, aluminum, silicon and the nine others that make up 99 percent of the Earth's crust. Historically, only scientists working on lab-scale projects had much use for them, so geologists had little incentive to look for new sources. The consequence is a severe lack of knowledge about the prevalence, availability and cost-effectiveness of energy-critical elements. This lack of knowledge breeds anxiety. In August 2010, for instance, the libertarian magazine Reason ran the headline "Forget peak oil. What about peak lithium, peak neodymium, and peak phosphorus?" In the case of lithium, the panic has begun to subside as we've learned more about the element's abundance. But will the same be true of the other 28 energy-critical elements? And what can the state of lithium supplies tell us about the rest of them?