The minerals used by clean-energy technologies

In a previous post, I offered a broad overview of the problems related to minerals needed for the clean-energy transition. To recap:

* clean-energy technologies are more minerals-intensive to build than their fossil-fuel counterparts;

* the growth of clean energy will rapidly raise demand for a set of key minerals;

* mining and processing of those minerals is geographically concentrated, often in countries with weak labor and environmental protections;

* mineral mines and processing facilities often pollute water, scar landscapes, and impoverish communities;

* production may not be able to expand fast enough to keep up with demand, which could cause supply constrictions and price fluctuations and slow the transition away from fossil fuels.

That’s the big picture.

In today’s post, I want to take a take a closer look at some of the biggest clean-energy technologies and the minerals required to build them. Specifically, I’ll cover batteries, solar PV, wind, geothermal, concentrated solar, and carbon capture and storage (CCS). I’m not going to get too deep into any one of these — just a quick tour.

I’ll be drawing heavily on a 2020 World Bank report that projects demand for key minerals under rapid decarbonization scenarios from the International Energy Agency (IEA) — specifically the RTS (reference technology scenario, or current policy), 2DS (2-degree scenario), and B2DS (beyond 2-degree scenario, aiming for 1.5). (The World Bank and IEA use the word minerals to refer to the mineral and metal value chain, and I do the same in this post.)

This tour will reveal which minerals are expected to be most in demand — which ones are certain to be needed and which depend on the direction taken by particular technologies. It will help focus attention on possible supply stress points.

It will also reveal that there is enormous uncertainty about the pace and scale of demand growth for specific minerals and minerals generally. Much depends on unpredictable developments in technology, policy, and politics. Epistemic humility is called for, along with policy focused on resilience. (More on policy in the next post.)

One fact that is certain: the more ambitious the world’s decarbonization efforts, the higher mineral demand will rise.

Here’s an overview table of energy sources and technologies and the key minerals they use:

Let’s start the tour with the 800-pound gorilla of minerals demand: batteries.

Batteries are the biggest growth sector for minerals demand

Of all the clean-energy technologies set to boom in coming decades, none will put a strain on minerals supply like batteries, shown as energy storage in the chart above. They account for about half of the projected growth in minerals demand over the next two decades in a rapid decarbonization scenario.

In large part, this has to do with the expected rise in battery-powered electric vehicles (EVs), which represent 90 percent of battery demand growth; the other 10 percent will come from growth in stationary storage, used to balance out wind and solar on the grid.

If the world targets 2°, minerals demand from energy storage will double from the baseline scenario; if the world targets 1.5°, it will more than double again.

Batteries, readers of my battery series will recall, are composed of two electrodes, a cathode and an anode, and an electrolyte through which they exchange ions. (The outlier is redox flow batteries, which pump a liquid electrolyte past electrodes.)

Depending on what those three parts are made of, batteries require different minerals. Many EVs still use lead-acid batteries, which use lead and sulfuric acid, but lithium-ion batteries (LIBs) are expected to rapidly take over the market, so demand for lead-acid batteries won’t grow much.

As for LIBs, most use graphite as the anode, which means graphite will be the most sought-after mineral in energy storage. Cathodes vary more widely. The most common use nickel, with various mixes of cobalt, lithium, and manganese also common. (It should be noted that lithium is used across all LIBs, not just for the cathode.)

It should be noted that these projections out to 2050 are to a large extent guesses, just an extension of the “average” LIB into the future. In fact, LIB technology could evolve a number of different ways, and other storage technologies could play bigger roles in subsequent decades.

“The assumption that Li-ion batteries dominate both the mobile and stationary market for the next decade is conservative,” the World Bank writes. “Post-2030, the scale of uncertainty is much greater, with a wide range of options in both markets.”

Consider the options for LIBs. For cathodes, NMC111 batteries use one part nickel, one part manganese, and one part cobalt, while newer NMC811 batteries use much more nickel and less cobalt. Tesla and other automakers are trying to eventually eliminate cobalt from their batteries; it’s too early to say how far they’ll get.

Right now, almost all anodes are graphite (a market dominated by China) but there is active development of zinc-air batteries that use air as the anode, sodium-ion batteries that use hard carbon as a anode, and solid-state batteries (which replace a liquid electrolyte with a solid one) that use lithium as an anode. What mix of technologies will triumph is still an open question, which means the precise trajectory of graphite demand is tough to predict.

If manufacturers seek to minimize cobalt, demand for nickel will rise. If solid-state batteries catch on, they could reduce demand for graphite. If zinc-air batteries catch on, they could dent demand for lithium, graphite, nickel, and manganese.

Post-2030, other storage technologies like flow batteries or a wide array of long-duration storage techs could become competitive. It depends on the evolution of policy and the electricity mix. Also worth noting: the practice of using second-life EV batteries as a form of grid storage could take off, which would trim total demand for new batteries.)

Finally, LIBs have made substantial advances in materials efficiency and those will likely continue, which could effect how sharply demand rises. (Read this RMI report for a bullish take on improvements in LIBs’ energy density.)

In terms of how geopolitically concentrated and environmentally destructive they are, the big minerals to watch here are graphite, nickel, lithium, and cobalt, but it’s impossible to know their precise mix in advance.

Solar voltaics love aluminum and copper

Solar is another technology that we are confident is going to grow like mad in coming decades, but it’s difficult to predict the exact trajectory of minerals demand.

The World Bank paper looks at four common PV technologies: crystalline silicon (crystal Si), which makes up about 85 percent of the current market, and three different “thin film” technologies that can be printed on flat sheets: copper indium gallium selenide (CIGS), cadmium telluride (CdTe), and amorphous silicon (amorphous Si).

All four are made primarily