The inconsistency of renewable energy production is one reason why power grids are still reliant on fossil fuels. For example, solar panels cannot generate energy at night and wind turbines do not work when the air is still.

But MIT researchers believe their energy storage device, which is a supercapacitor rather than a battery, could provide cheap storage of electrical energy that could help even out the ebb and flow of renewable energy generation.

The technology could even be incorporated into the concrete foundation of a house, where it could store a full day’s worth of energy while adding little cost to the construction of the foundations while still providing the structural strength required.

The researchers also envision a concrete roadway that could provide contactless recharging for electric cars as they travel over that road.

Capacitors typically consist of two electrically conductive plates immersed in an electrolyte and separated by a membrane...