What if ordinary red house bricks could store the energy we need to power our homes? As crazy as that sounds, it’s a serious question that scientists at Washington University in St. Louis are looking into. The key to this potential energy breakthrough is lowly rust, or iron oxide. It turns out that rust is what makes red bricks red, and it works sort of like an “ion sponge” to store and conduct electricity.

Scientists have previously noticed red bricks’ ability to absorb and store the sun’s energy but the WashU researchers kicked it up by developing a conducting polymer that remains trapped in bricks and essentially converts a brick house into a supercapacitor. So some day we might be using “smart bricks” to power our homes. The WashU team noted that any red bricks, even used ones, will work. For their experiment, they bought bricks at Home Depot for 65 cents each.