The big promise of electric cars is that they’ll radically cut down on carbon emissions, helping fight climate change. And at first glance, they do so — after all, you don’t have to fill the tank with fossil fuels every few days, and there are no emissions from the car itself.

But the truth is a little murkier. Electric cars may not produce emissions themselves, but they have much bigger batteries requiring exotic metals, potentially creating a whole different environmental issue when those batteries near the end of their life span.

So what can be done with electric car batteries? Can they be recycled?

Electric cars are still in their infancy, and as such, we haven’t really had to deal with the ecological issues that will arise when EVs reach the end of their lifetimes.

However, there are situations where an EV is no longer road-ready. There are a few that might be at the end of their life, or an EV might have been involved in an accident that renders it undrivable.

Thankfully, in those scenarios, batteries can be, and are sometimes, recycled. There are a number of startups out there that can turn an EV battery into a mass of elements, including copper, cobalt, nickel, and lithium. That mass is then shipped off overseas to be processed into materials that can then be turned into new electric car batteries.

Of course, ultimately, we’ll want car batteries to be processed locally, ensuring that they don’t have to be shipped off just to be recycled. There are a number of startups working on that, and plants that can facilitate the recycling of batteries are set to be built in the U.S. soon. One such startup is the Toronto-based Li-Cycle, which is building a plant in Rochester, New York, to process batteries into materials that can be used for new EV batteries.

Unfortunately, much of the time, the process of deactivating a lithium-ion battery involves burning them to remove unwanted materials — and that often ends up removing some of the wanted materials too. Not only that, but only a fraction of lithium-ion batteries in the U.S. are recycled at all, with the rest ending up being smelted.

Thankfully, we have some time to perfect the tech on recycling EV batteries — the need isn’t massive yet. But it’s important to continue developing the technologies we do have. As electric cars become increasingly popular, we’ll soon need to recycle millions of electric car batteries per year.

Of course, car manufacturers have one strong incentive to recycle batteries: They need to make a lot more of them. The materials that go into building EV batteries are limited, and it’s not currently clear exactly how manufacturers will find enough to support sales over the next decade or so.

Plenty of startups are hoping to meet this need by developing new ways to turn batteries back into their raw materials, to then be used for new batteries, while losing as little as possible. A company called Redwood Materials, for example, uses the energy left in batteries to recover the materials in them through converters that separate the metals.

We still have a long way to go before we successfully recycle all electric car batteries, but there are plenty of companies — and carmakers themselves — working on it.