Researchers have found a way to turn cement into a supercapacitor. This would make it possible to store electricity in it and could, in theory, turn housing foundations and roads into relatively cheap batteries. The research, conducted by the Massachusetts Institute of Technology, has been
published in the scientific journal PNAS. In addition to cement powder, water and black carbon were used to create the supercapacitor. This is because cement by itself does not conduct very well, but black carbon does. Moreover, the latter material is relatively cheap.
When these materials are combined in a specific way, a conductive nanocomposite is created. This is because water easily combines with the cement powder, but the particles of black carbon actually repel water and then clump together. This creates 'rank-like' shapes in the hardening cement that can act as a network of wires. The cement is then cut into thin sheets. If a membrane and electrolyte are then added, such as potassium chloride, the capacitor should be able to store and release energy. This does require a lot of cement. 10kWh, enough to power an average household for a day, is expected to require 45 cubic metres. That is about as much as is used for the foundation of a standard residential house. The cement capacitors the researchers created, measuring 1mm thick and 1cm wide, had enough power to run a few LED lights. The research team believes that if the same method is used to build roads and car parks, the electric concrete could theoretically store renewable energy and deliver it to electric cars via induction charging. As the materials are relatively cheap compared to other home batteries, this is also potentially a way for third-world countries to store green energy.
The group has patented the technology and is now trying to scale it up. This is no easy task, the team argues. As supercapacitors increase in size, their electrical conductivity typically decreases. The next goal is to make the cement capacitor as powerful as a 12V car battery.