Using dirty water to generate clean water may sound like an unhygienic scam, but it’s about to become reality in Aarhus, Denmark. The city’s Marselisborg Wastewater Treatment Plant just got a new, state-of-the-art upgrade enabling it to generate 192 percent of its energy needs from sewage.
Wastewater processing facilities are notoriously energy-hungry, consuming roughly eight percent of the world’s electricity. With new energy-efficiency measures and its $3.19-million electricity-generating upgrade, the Marselisborg plant is a glimpse into the future of wastewater power.
The system makes energy by harvesting and burning biogas produced by the bacteria feeding off of sewage. Like at most plants, this wastewater is kept in massive, heated digesters encouraging bacteria growth and breaking down organic material. Biogas is typically burned off for environmental reasons, but the Marselisborg plant takes it a step further, essentially using the biogas as fuel for energy production.
The plant’s extra electricity will be sold back to the city’s grid. Officials project that the multimillion-dollar upgrade will pay for itself in just five years. Other Danish cities, including Copenhagen, are already making plans to replicate the Aarhus system.