A square meter of concrete can store the electricity of two AA batteries.

Scientific American looks at a weird new power source, using probably the most common building material in the modern world as a kind of rechargeable battery:

Experimental concrete batteries have only managed to hold a fraction of what a traditional battery does. But one team now reports in Buildings that it has developed a rechargeable prototype that could represent a more than 900 percent increase in stored charge, compared with earlier attempts.

A live-in concrete battery might sound unlikely.

“This is adding extra functions to the current building material, which is quite promising in my view,” says study co-author Emma Zhang, who worked on the new battery design at Chalmers University of Technology in Sweden and is now a senior development scientist at the technology company Delta of Sweden. She and her colleagues mimicked the design of simple but long-lasting Edison batteries, in which an electrolyte solution carries ions between positively charged nickel plates and negatively charged iron ones, creating an electrical potential that produces voltage. In this case, the researchers mixed conductive carbon fibers into cement (a main ingredient of concrete) to substitute for the electrolyte. They also embedded layers of a carbon-fiber mesh, coated in either nickel or iron, to act as the plates.

This setup proved capable of discharging power and then recharging.

You can read the original research here, in Buildings.