Minor Metals and Renewable Energy: What Solar Panels and Wind Turbines Need

By Sheryl A. Singerling and Nedal T. Nassar, USGS National Minerals Information Center

More solar and wind

Solar photovoltaic (PV) and wind power are projected to make up a growing share of U.S. electricity capacity: about 11 percent (118 gigawatts) in 2016, and 36 percent (566 gigawatts) by 2050 (EIA, 2017).

U.S. generating capacity in gigawatts (GW) — wind (blue), solar PV (yellow) and all other sources (gray) — in 2016 and projected for 2050. USGS, from EIA data.

What "minor metals" are

Minor metals are produced in small amounts worldwide compared with the widely produced base metals — often as byproducts of mining or processing them. Each type of solar and wind technology uses different ones, and the metals:

• have complex supply chains;
• are mostly produced outside the United States;
• are used in many other products too.

More of them will be needed as solar and wind grow (Nassar and others, 2016).

Solar power

Solar PV comes in two kinds:

It is not yet clear which, if any, thin-film type will dominate.

The minor metals in wafer and three kinds of thin-film solar cells, with their source ores, the share of U.S. supply imported in 2016, and their main competing uses. USGS.

Why the supply chain is complicated

• Trace amounts: the metals occur in only traces in their deposits, so they are usually recovered as byproducts of ores such as bauxite, chalcopyrite, gold and sphalerite. Their supply depends on demand for the main ore.
• Competition: they are also used in batteries, electronics, fiber optics, flat-panel displays, integrated circuits, metallurgy and thermoelectronics, so solar makers compete for them.
• Imports: the United States is highly net import reliant (imports minus exports, adjusted for stock changes; Fortier and others, 2015) on many of them. It imports more than half of the gallium, germanium, indium, silver and tellurium it uses — from countries such as Canada, China and Mexico — so a trade disruption could restrict supply.

Wind power

Modern wind turbines come in three types, which differ in whether they have a gearbox. That affects how often they need maintenance, and how many minor metals they use:

Wind turbine types and the minor metals in the hybrid and direct drive designs' magnets, with 2016 U.S. import reliance and competing uses. USGS.

The rare earths: the magnets use several rare-earth elements (REEs) — dysprosium, neodymium, praseodymium and terbium — for the properties they give.

• Like the solar metals, they occur in trace amounts, so mining them depends on the economics of the deposits' main products.
• They are also used in hard disk drives, electric-vehicle motors and other magnets, and in phosphors for displays and lighting — demand that can affect supply for wind power.
• Since 2016, the United States has had no operating rare-earth mines and relies entirely on imports, mainly from China, for these four elements and for goods such as magnets that contain them.

Key points

• Electricity capacity is projected to grow to meet demand from homes, businesses and industry, with a growing share from solar and wind — and so more minor metals. How much depends largely on which technology wins (Nassar and others, 2016).
• Future supply and demand are uncertain: the metals are byproducts, have competing uses, and are largely imported, especially from Canada, China and Mexico.
• The USGS National Minerals Information Center tracks production, consumption and trade in minor metals and other nonfuel minerals, forecasts trends, and publishes updates to help policymakers and industry anticipate changes in supply.

More: USGS National Minerals Information Center.

Sources

Based on Minor Metals and Renewable Energy—Diversifying America's Energy Sources, by Sheryl A. Singerling and Nedal T. Nassar, USGS Fact Sheet 2017–3061, U.S. Geological Survey; a work of the United States government in the public domain. The three figures are taken from the fact sheet's PDF, which the import had left out; so is the opening of the solar section, which the import had cut.