Building a clean-energy future will take a lot of things, the most obvious being lots of money and a well trained workforce capable of keeping the needed technology up and running.

Less obvious, perhaps, but equally important, is this: an adequate supply of rare earth metals.

While not actually rare — except for the element promethium — rare earth metals are a special class of elements that share similar chemical properties. They’re also vital materials for a variety of clean-energy technologies, including electric-car batteries (lithium), compact fluorescent light bulbs (neodymium) and solar panels (gallium).

What makes rare earth elements so special is that they can be alloyed with other metals to produce materials that are exceptionally strong, lightweight and magnetic. They also have valuable optical properties that are important in such applications as lasers.

As demand for clean-energy technologies has grown, one of the biggest concerns that’s arisen centers on the future security of rare earth metal supplies. That’s because, since the early 1990s, most of the world’s rare earth metals have come from just one place: China. Today, China supplies more than 95 per cent of the globe’s rare earth metal needs.

Which explains why the US Department of Energy is now working to develop its first-ever strategic plan for rare earth metals and other materials needed for clean-energy technology. It’s asking industry leaders, research labs, academics and any other organisations that have an interest or stake in rare earth metals to provide it with information related to demand, use, supply, recycling and cost issues.

The Energy Department’s goal is to build a better understanding of rare earth metals supply and demand, identify ways to use such materials more efficiently and see if there are any opportunities for developing substitutes for those elements.

“It goes without saying that diversified sources of supply are important for any strategic material,” said David Sandalow, Assistant Secretary of Energy for Policy & International Affairs. “So too are substitutes and strategies for re-use and recycling. If rare earth metals are going to play an increasing role in our economy, we need to pursue those strategies.”

Speaking at a Washington, DC, conference on rare earth metals last month, Sandalow noted that “there’s no reason to panic, but every reason to be smart and serious as we plan for growing global demand for products that contain rare earth metals.”

“The United States intends to be a world leader in clean energy technologies,” he said. “Toward that end, we are shaping the policies and approaches to help prevent disruptions in supply of the materials needed for those technologies.”

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