Scientists from the University at Buffalo have used a sapphire-colored dye – methylene blue – to power redox flow batteries.
According to the researchers, the blue dye when dissolved in water stores and releases energy on cue.
They could someday power large, rechargeable liquid-based batteries, enabling future wind farms and solar homes to stockpile electricity for calm or rainy days.
“Methylene blue is a widely used dye. It can be harmful to health, so it’s not something you want to dump into the environment without treating it,” says lead researcher and assistant professor, Timothy Cook. “There’s been a lot of work done on ways to sequester methylene blue out of water, but the problem with a lot of these methods is that they’re expensive and generate other kinds of waste products.”
“But what if instead of just cleaning the water up, we could find a new way to use it? That’s what really motivated this project,” says first author and chemistry PhD student, Anjula Kosswattaarachchi.
According to the researchers, the study is just the first step in assessing how and whether methylene blue from industrial wastewater can be used in batteries.
To their credit, what Cook and Kosswattaarachchi have shown so far is that methylene blue is good at important tasks associated with energy storage.
As part of their study, the scientists built two simple batteries that employed the dye – dissolved in salt water– to capture, store and release electrons.
The first battery the researchers made operated with near-perfect efficiency when it was charged and drained 50 times: Any electrical energy the scientists put in, they also got out, for the most part.
Over time, however, the battery’s capacity for storing energy fell as molecules of methylene blue became trapped on a membrane critical to the device’s proper function.
The scientists thus used a far more advanced membrane for their second battery which maintained the near-perfect efficiency of the first model, but had no notable drop in energy storage capacity over 12 cycles of charging and discharging.
The team is now hoping to take the research one step further by obtaining real wastewater from a textile mill that uses the dye.
Image, video and content; Meredith Forrest Kulwicki/University at Buffalo