Hybrid Energy Tech Could Clean Wastewater for Free

A combination of microbial fuel cell and reverse electrodialysis is efficient enough to make sewage treatment energy neutral

Engineers at Pennsylvania State University have combined two cutting-edge energy-generation technologies—microbial fuel cells and reverse electrodialysis (RED)—to make a hybrid device that could generate enough energy from wastewater to power its treatment and even feed some extra electricity into the grid. The engineers report their invention this week online in Science.

“The goal I’ve been pursuing is to ensure the energy sustainability of the water infrastructure,” says Bruce E. Logan, the professor of civil and environmental engineering who led the research. The energy potentially available in municipal wastewater is surprisingly high—more than nine times as high as what’s needed to process it. “It wouldn’t take much to think we could be at least energy neutral,” he says...