The cement that could turn your house into a giant battery
Concrete is perhaps the most commonly used building material in the world. With a bit of tweaking, it could help to power our homes too.
On a laboratory bench in Cambridge, Massachusetts, a stack of polished cylinders of black-coloured concrete sit bathed in liquid and entwined in cables. To a casual observer, they aren't doing much. But then Damian Stefaniuk flicks a switch. The blocks of human-made rock are wired up to an LED – and the bulb flickers into life.
"At first I didn't believe it," says Stefaniuk, describing the first time the LED lit up. "I thought that I hadn't disconnected the external power source, and that was why the LED was on.
"It was a wonderful day. We invited students, and I invited professors to see, because at first they didn't believe that it worked either."
Yet the Sun isn't always shining, the wind isn't always blowing, and still waters do not, in megawatt terms, run deep. These are energy sources that are intermittent, which, in our energy-hungry modern world, poses a problem.
