Buildings as rechargeable batteries

With the increasing electrification of the world in general, and of cities in particular, it is not only imperative to increase alternative production sources of clean and environmentally friendly electricity, but also new systems for its storage. This is the aim of an experiment at the Division of Building Technology, Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden. The experiment has shown that concrete buildings could be constructed to serve as rechargeable electric batteries. According to one of the study’s authors, Emma Zhang, who told Scientific American, the idea is to “add additional functions to the current building material”, and the result, she says, “is quite promising”.

In their study, Zhang and her colleagues took as a model the batteries that Edison invented, because of their simple design and long-lasting performance. According to that model, an electrolyte solution transports ions between positively charged nickel plates and negatively charged iron plates, so that the process creates an electrical potential that produces voltage. In their prototype, they used cement (the main ingredient in concrete) mixed with conductive carbon fibres as the electrolyte. They then inserted layers of carbon fibre mesh coated with nickel and iron on either side to act as plates. The system has proven to be durable and capable of discharging energy and then recharging again.

Although the new design stores more than 10 times the energy stored by previous prototypes, there is still a long way to go before buildings can be constructed as sufficiently efficient batteries. At the moment, 200 square metres of concrete, as Zhang tells Scientific American, “can provide [only] about 8 percent of the daily electricity consumption” of a typical US household.

The fact that concrete is the most widely used material in the world (after water) allows us to imagine the enormous potential that buildings could have if we were to construct them as giant batteries for storing electrical energy. On the one hand, we would solve the problem of the toxicity and scarcity of the materials with which rechargeable batteries are currently made, which would then be produced with others as abundant as iron, nickel or carbon.  On the other hand, we would solve the issue of storing large amounts of energy from natural sources such as the wind or the sun, for use when these are not present due to changing weather conditions. Chalmers University of Technology is not the only study on converting buildings into batteries. Another experiment at the University of Washington also aims to convert building bricks into batteries, but we’ll leave that for another time (and anyway, if you’re curious, you’ll find a link in our sources to find out more).