Each year, Spain generates more than one million tons of dry sewage sludge, an urban waste with little economic value and complex environmental management.
These wastes, resulting from wastewater treatment processes, contain high levels of organic matter, phosphorus, nitrogen, and metals. This makes them a challenge for small and medium-sized municipalities.
However, a new technology developed by the Chemical Institute for Energy and Environment (Iquema) proposes an innovative solution: transforming sludge into activated carbon to manufacture sustainable batteries.
Pioneering technology with environmental and energy impact
In collaboration with the Villaviciosa wastewater treatment plant, managed by Epremasa, the scientific team at Iquema has managed to convert these wastes into porous conductive material through a process that includes:
- Drying and chemical treatment
- Pyrolysis at 800 °C, a thermochemical technique that decomposes organic matter
- Mixing with sulfur to manufacture electrodes
The result is sulfur-based batteries that, according to researchers Almudena Benítez and Azahara Cardoso, can triple the storage capacity of traditional lithium-ion batteries. This advancement has direct implications for sectors such as electric mobility, which still faces autonomy limitations.
Circular economy applied to energy
This development is part of a broader line of research at Iquema, focused on the reuse of urban and agro-industrial waste to create sustainable energy technologies.
Until now, materials such as olive pits or almond shells had been explored, but sewage sludge represents an abundant and underutilized source, especially in locations without infrastructure for its use.
“Transforming urban waste into key components for batteries is integrating sustainability, innovation, and circular economy,” they highlight from the institute.
Key benefits of sustainable batteries
- Reduction of toxic waste and pollutant emissions
- Less impact from lithium and cobalt mining
- Greater energy efficiency and stabilization of renewable networks
- Recovery of valuable materials and energy autonomy
- Economic savings and longer device lifespan
These batteries allow storing energy from renewable sources such as solar and wind, compensating for their intermittency and improving the stability of the electrical grid.
A firm step towards the energy of the future
Beyond the laboratory, this technology opens new possibilities for converting urban waste into energy solutions, reducing dependence on critical raw materials and strengthening environmental and economic resilience. In a global context of energy transition, sustainable batteries not only store energy: they store the future.
