Your future house could have a foundation that’s able to store energy from the solar panels on your roof—without the need for separate batteries.

MIT engineers developed the new energy storage technology—a new type of concrete—based on two ancient materials: cement, which has been used for thousands of years, and carbon black, a black powder used as ink for the Dead Sea Scrolls around 2,000 years ago.

Carbon black conducts electricity, and the engineers discovered that if it’s mixed with cement and water in a specific way, it forms a long, branching network of carbon “wires” as the cement hardens. That turns the material into a supercapacitor, a device that stores an electric charge. “All of a sudden, you have a material which can not only carry load, but it can also store energy,” says Franz-Josef Ulm, a civil engineering professor at MIT and one of the authors of a new study about the tech.

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