If the 19th century was the age of coal and the 20th the age of oil, the 21st century is starting to look like the age of lithium. A metal so soft it can be cut with a steel knife and for years known for its role treating bipolar disorder, lithium has quietly become the most important metal for several important industries — electronics, electric vehicles and renewable energy — because of its importance to energy storage. Rechargeable lithium ion batteries are now in everything, but have become indispensable to efforts to fight climate change.

Because renewable energy is often generated at different times from when demand is greatest, storage is a necessity (conventional plants can increase power output to meet demand, up to a point) and most of the time, this means lithium batteries. Similarly, electric vehicles use lithium batteries, helping to decarbonize transportation tailpipe emissions. Currently, most EVs are high end, luxury cars, but in the future it’s likely that trucks, police cars, firetrucks, ambulances and even some military vehicles will be battery-electric. Manufacturers are already experimenting with battery electric aircraft in a bid to reduce emissions from that sector. Meanwhile the multibillion dollar electronics industry continues to rely on lithium batteries.

But despite its relative abundance in the Earth’s crust, commercially exploitable lithium is relatively rare. Around 75 percent is believed to be in salt flats in South America. Interest is also growing in spodumene, a lithium-bearing mineral more widely distributed around the world, and extracting it from sea water. But the demand for lithium is only expected to grow. To make things complicated, rising tensions between the United States, its allies and China, as well as a desire for the former to support domestic industry, are expected to lead to increased competition for lithium supplies. In 2018, the United States Department of the Interior included lithium on a list of strategic minerals and the Biden Administration permitted a mining project to go forward over the opposition from environmental and Native American groups.

Moreover, mining lithium is quite environmentally destructive. In South America, lithium concentrations are mixed with water to form a brine and evaporated in great ponds. It produces the lithium needed for batteries, but consumes water in an already dry part of the world. The other major way of producing lithium, mining spodumene, also harms the environment. 

So the question remains, with such an important resource, why are we intent on wasting it on buses and trains. Many transit agencies are investing in battery electric vehicles as a quick and easy way to reduce carbon emissions. But buses and trains don’t need batteries to be electric, they can be run off catenary wires overhead. Not only does this mean that the vehicles don’t need batteries, the batteries are heavy and take up a lot of space, so the vehicles end up lighter and have better acceleration. This makes them faster and capable of carrying more people.

While building overhead wires can be expensive, they are other worthwhile investments for greening public transport than “sexy” battery electric buses and trains for several reasons. In addition to reducing the demand for strategic minerals like lithium, they use an existing, mature, proven technology — catenary systems were invented in the late 19th century — and as such their performance and capabilities at both high and low temperatures are known, unlike battery powered buses, which have suffered from problems with cold weather. 

Lastly, we should consider if it’s even a good idea to replace all gas and diesel powered cars with electric ones. Jevons’ Law suggests that even if we were to develop batteries that used less lithium, the price would decrease and demand would rise until we went back to needing more. Cars represent one of the biggest potential markets for lithium batteries, but emissions from engines are only one externality. An electric car can still kill children, walkers and cyclists with ease, still drives on tires made from oil, over roads made from oil, must be parked in a lot made from oil. Investing in public transportation and high density housing in cities would allow those parking lots and roads to be reduced in size or eliminated altogether. People would be safer, parks could be built to mitigate the urban heat island effect and the need to consume vast acreages of farmland or wilderness for new subdivisions and highways. 

Let us take only the lithium we absolutely need and avoid the mistakes of the last century.