The world is flushing billions of dollars of energy down the drain every year, according to a United Nations research report released this week. The paper, from the United Nations University’s Institute for Water, Environment and Health, finds that biogas obtained from worldwide supplies of human poop could power up to 138 million homes. 

The UN is determined to halve the world’s untreated wastewater stores by 2030. (Wastewater is any water contaminated by human activity so that it's unsafe to drink.) Much of the world doesn’t have access to adequate sanitation facilities, and an estimated billion people defecate out in the open, causing deadly outbreaks of diarrhea and other illnesses. But in places without sanitation infrastructure, pooping in a field or behind a tree often seems easier than buying toilets and paying for their upkeep. Selling poop’s economic value might help encourage the up-front investment in sanitation, or so the authors of the paper hope.

An anaerobic waste facility in Uganda. Image Credit: Corinne Schuster-Wallace, UNU-INWEH

Biogas, comprised mostly of methane, can be harvested as the bacteria within human waste breaks down inside a sealed container. Afterward, the residue left over can be dried and charred to create a charcoal-like fuel, which also reduces the need to harvest wood for heating. Waste to Wealth—a pilot program in Africa that the Institute for Water, Environment and Health is involved in—is currently testing poop-to-energy technology in institutions like schools and prisons in Uganda. 

Using average estimates for how much a person poops per day and how much energy could be derived from those solids, the report declares that the equivalent of $9.5 billion of natural gas is being thrown or flushed away every year. Even if the waste-energy systems were only used by people who currently practice open defecation, the biogas harvested could be worth more than $200 million per year, generating electricity for more than 10 million households. And suddenly, the clean energy of the future is looking pretty dirty. 

[h/t: CityLab]