Poo Power: This Danish City is First to Tap Sewage Energy to Pump Drinking Water

A city in Denmark will use energy from household sewage to distribute drinking water to its residents. In the city of Aarhus in Denmark, the water system that provides drinking water to more than 200,000 residents will be powered by the Marselisborg Wastewater Treatment Plant.

After improvements were made, the Marselisborg facility is now capable of generating over 150 percent of the electricity needed to run the plant, and the excess could be used in pumping drinking water throughout the city, New Scientist reports.

"We are about to be the first energy neutral catchment area," Mads Warming of Danfoss Power Electronics, which provides the technology for city's municipal water utility Aarhus Water, said in a statement.

The plant generates energy from biogas it creates out of household wastewater, which includes sewage. Energy is pumped into digesters kept at 38 degrees Celsius and filled with bacteria. The resulting biogas, which is mostly methane, will be burned to make heat and electricity.

According to a report from Energy Live News, water management will consume up to 8 percent of global electricity and represent up to 40 percent of the power usage of local authorities. The energy-sufficient Marselisborg facility acts as a power station and biorefinery, producing 40 percent more electricity than it needs and 2.5 gigawatts of a year's worth of heat. The total energy it provides is 192 percent and is equivalent to the total energy needs for drinking water supply and wastewater treatment in the area.

"For the first time, you have for 200,000 people, an area in the city where they don't use any energy neither for the drinking water side or the wastewater side and that's purely based on the wastewater itself from the households," Warming told Energy Live News. "So there's no external carbon coming in from the food industry or from other wastewater facilities. There's no wind or solar power used. It's purely based on what these 200,000 people consume of drinking water and produce wastewater."

Other cities in Denmark, including Copenhagen, have been trying to do the same. In the United States, Chicago and San Francisco are also looking at tapping the new energy source.

According to Denmark's Ministry of Environment and Food, the improvements in the plant will mark a milestone for energy-efficient water technology in Denmark and around the world. "Treatment plants must move forward from being energy guzzlers to being energy producers, and we have a really good example of this here," environment minister Eva Kjer Hansen told Danish media outfit The Local.