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What we usually flush away could one day help power our cars. A team at the University of Córdoba has found a way to turn municipal sewage sludge into a key material for a new generation of more sustainable batteries. As the researchers explain, this urban waste, normally seen as a problem, “now has value.”

 

Working at the Chemical Institute for Energy and the Environment (Iquema) and a wastewater treatment plant in Villaviciosa, Córdoba, the group has managed to convert sewage sludge into activated carbon, a highly conductive material used in sulfur-based batteries. In simple terms, they take the sludge, dry it, treat it chemically with potash to change its structure, then heat it to around 800°C in a process called pyrolysis. The end product is a porous, stable, conductive carbon that can be mixed with sulfur and used to make battery cathodes.

 

The potential impact is significant. Sulfur batteries can store more energy than conventional lithium ion batteries and do not rely on critical raw materials such as lithium or cobalt, whose extraction is expensive, environmentally damaging and often politically sensitive. By using sewage sludge as a raw material, the process also helps deal with an environmental headache that affects many cities. As the team highlights, it is about “transforming waste into solutions, pollution into electricity, and garbage into opportunities.”

 

Early lab tests have been promising. The carbon obtained from the sludge has shown good electrical conductivity and works with standard battery manufacturing techniques. There are still hurdles to clear, including long term stability, scaling up production and ensuring reliable charge and discharge cycles. Even so, the researchers believe this approach offers “real hope for cheaper, cleaner and more sustainable electric cars.”

 

For now, it is a research project rather than a commercial product, but it is also a clear example of the circular economy in action. The idea that the next step in electric mobility could come from what lies beneath our streets is striking. As the scientists suggest, the “spark” for future transport might quite literally be hiding in the sewage.

 

 

Image: Perplexity