When it comes to any electronic device, it’s all about the battery. And for electric cars, it’s no different. No one wants get behind the wheel of a battery-powered car and have the juice run out halfway to a destination. You can’t just plug in anywhere, especially if you’re in the middle of nowhere.

Battery developer Phinergy and metal manufacturer Alcoa teamed up a while ago to work on this problem. This week in Montreal, they showed off their modified Citroen C1, which has two batteries: one lithium-ion and the other, aluminum-air. When combined, these batteries promise to give the car more than a thousand miles of range.

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In the Citroen, the lithium-ion battery acts as the main energy source, as it does in most electric vehicles, such as the Nissan Leaf and Tesla Model S. Alone, the lithium-ion battery can only get you so far. In a Leaf, for example, you can go about 80 miles before needing a recharge. In a Model S, almost 300 miles. Both of those offer plenty of range for most people, since the majority of commuters travel 31 miles per day. But Tesla’s car is expensive and the Leaf, while more affordable, still gives people “range anxiety” because what if they need to go more than 80 miles in one day?

That’s where the aluminum air battery would come in. On the Citroen, it serves as a range extender, letting you drive a thousand, carefree miles.

Aluminum-air batteries are lighter than lithium-ion ones and more energy dense. But they’re not great for use as a primary energy source in a car because they can’t be charged at home. Instead, the batteries would be swapped out at a specialized service station when their energy was drained.

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According to CBCNews, a person’s car would still rely on its rechargeable lithium-ion battery and automatically switch to aluminum-air battery powered when it needed to. And because most car trips are about 30 miles or less, the aluminum battery would not be used frequently. Alcoa estimates drivers would run down the aluminum battery’s charge once per year.

If the companies can make the range extender affordable, we could see a lot more electric cars on the roads and a lot less anxiety.