Common red masonry bricks – the same type used in construction projects, including many data centers – can be adapted and used to store electricity, researchers claim.
A team from Washington University in St. Louis has found that the red pigment in bricks can trigger a chemical reaction, in much the same way rust occurs, that enables bricks to store a significant amount of energy.
Specialized bricks aren’t required; the synthesis works with any kind of brick, according to an article published on the university’s news site. The team used common bricks bought from the Home Depot in Brentwood, Missouri, for 65 cents apiece.
Surprisingly, the process doesn’t work by simply absorbing and storing the sun’s energy as heat in the brick’s mass—a common energy transference that’s been used in construction for thousands of years. Instead, it’s more of a supercapacitor-like operation: “Supercapacitors store electric charge, in contrast to batteries, which store chemical energy,” writes Julio D’Arcy, assistant professor of chemistry at Washington University, in The Conversation.
A conducting polymer called PEDOT, which is used in traditional battery-substitute supercapacitors, works well with the porous structure of bricks: “In this work, we have developed a coating of the conducting polymer PEDOT, which is comprised of nanofibers that penetrate the inner porous network of a brick; a polymer coating remains trapped in a brick and serves as an ion sponge that stores and conducts electricity,” D’Arcy said in the university publication..
The red pigment in bricks — bricks are made from clay that contains iron oxide, or rust — is essential for triggering the polymerization reaction, the researchers explain.
D’Arcy writes in The Conversation: “We fill the pores in bricks with an acid vapor that dissolves the iron oxide and converts it to a reactive form of iron that makes our chemical syntheses possible. We then flow a different gas through the cavities to fill them with a sulfur-based material that reacts with iron. This chemical reaction leaves the pores coated with an electrically conductive plastic, PEDOT.”
The bricks could be connected to solar panels in lieu of batteries, D’Arcy suggests. Powering IoT sensors could be a possible use-case.
A couple of bits of brick could power an LED, D’Arcy estimates, while 60 bricks could power emergency lighting for 50 minutes, after a 13-minute charge.
This isn’t the first time rust has been turned into a useful energy-creating medium: Disposable hand warmers produce heat through oxidization. Heat is generated when the included iron particles are exposed to air. Oxygen molecules react with the iron, making rust, and that chemical reaction produces heat for one’s hands in a pocket.
The brick concept needs to scale still, the group acknowledges. A drawback to traditional supercapacitors is that the technology isn’t as capacious as battery chemistry. The electrical charge can be renewed repeatedly without wearing out, unlike batteries; however, supercapacitors don’t store the same amount of power as a battery, mass-for-mass.
That’s an issue with the red bricks too, D’Arcy points out. Transforming the nanofibers into composites is one angle the researchers will be pursuing. Those nanofibers will in turn contain semiconductors, which could improve the process.
“Our goal is to develop bricks that are patterned and ready to be stacked without the need for wires. We intend to produce devices that can be assembled like Lego blocks,” D’Arcy writes.