Damian Stefaniuk and his colleagues at the Massachusetts Institute of Technology (MIT) had an idea. They created an energy storage device known as a supercapacitor from three basic, cheap materials. Water, cement and a soot-like substance. From this experiment would come concrete that works like a battery. How does it work?
Supercapacitors differ from batteries in important ways. They can charge much faster than a lithium-ion battery. But they quickly release the energy they store. That is why they do not work on devices such as mobile phones, laptops or electric cars.
Energy in the foundation
But carbon cement supercapacitors could change that. “Technology can help solve an important problem: renewable energy storage,” they say. What would concrete that works like a battery be useful for? For example, to create roads that store solar energy. They would free it to recharge electric vehicles wirelessly while driving on the road.
Another option would be house foundations that store energy: “They would be walls, foundations or columns that store energy inside,” says Stefaniuk. But it’s still early. For now, the concrete supercapacitor can store just under 300 watt-hours per cubic meter. It would be enough to power a 10-watt LED bulb for 30 hours. «It may not seem like much. “But a house with a foundation containing 30-40 cubic meters of concrete could meet daily energy needs.”
The supercapacitor works thanks to an unusual property of carbon black: it is highly conductive. When combined with cement powder and water, you get a kind of concrete filled with networks of conductive material. It takes on a shape that resembles tiny roots that always branch. By applying electric current to the salt-soaked plates, an electric field was created. «It would work in an isolated house powered by solar panels. “It uses solar energy directly during the day and energy stored in the foundation at night.”
Other impacts
A possible problem would be the environmental impact. Cement production causes 5-8% of carbon dioxide emissions from human activity. And moving from lab scale to implementation brings other complexities.
In any case, projects like this raise new perspectives. Perhaps our offices, roads and homes will play an important role in a world powered by clean energy.
