Over 20 years ago, two geologists made a stark prediction in Scientific American: “Probably within 10 years,” they wrote, “global production of conventional oil will begin to decline.” This argument, which became known as “peak oil,” captured public attention for well over a decade, sparking worries that abundant reserves of oil would give way to scarcity, runs on gas stations, and sky-high inflation. 

Peak oil, however, never came to pass. U.S. oil production increased far beyond the peak oil predictions, thanks to the increased use of “fracking” and other production methods. The term faded out of use, and concerns about oil shifted from a fear of running out of oil to fears of runaway global warming.

 Now, as the world begins to slowly shift to renewable energy sources, there is a new focus on the materials that will be required to build electric vehicles, solar panels, wind turbines, and much more. According to the International Energy Agency, the average electric car requires six times the mineral inputs of a conventional gas-powered car; an offshore wind turbine, meanwhile, requires nine times the mineral inputs of a typical gas-fired power plant.

 So, will we run out?

 There is no doubt that clean energy — that is, solar, wind, geothermal, nuclear, and other sources that do not produce greenhouse gas emissions — requires more mineral inputs than power plants run on fossil fuels. The IEA estimates that if the world builds enough renewable energy to meet the goals established in the 2015 Paris Agreement, mineral demand will double or quadruple in the next 20 years. Countries will need copper for power and transmission lines, lithium for batteries, silicon for solar panels, and zinc for wind turbines.

But there are a few reasons to think that — even as the world prepares to mine huge quantities of minerals — we won’t run out anytime soon.

Abigail Wulf, vice president of critical minerals for Securing America’s Future Energy (SAFE), a D.C.-based energy think tank, says that when minerals become valuable enough, people get motivated.

“It all has to do with economics,” she said. “If people get super desperate for these minerals, they will find very creative ways to find them.”

The first is that there is a difference between the available reserves of a mineral and the resources of that mineral. Reserves are the amount of a mineral that humans know they can efficiently and economically mine. Resources are the best guess of the total amount of that mineral available in the world — whether they are cost-effective to mine or not.

Wang said that there will probably be enough minerals — and that the environmental impacts of mining them should pale in comparison to the damages of fossil fuels. (Humanity “mines” billions of tons of fossil fuels from the ground every year; even a huge increase in mineral mining will only be millions of tons.)