How Wastewater Could Power Cities and Feed the Future

Every year, the world produces 359 billion cubic metres of wastewater—enough to fill Lake Geneva four times over. Hidden in this vast volume is a surprising resource: over 800,000 gigawatt-hours of chemical energy, roughly equal to the yearly output of 100 nuclear power plants. Now, scientists are turning to microbial electrochemical technologies (METs) to unlock this potential while also cleaning the water.

METs work by using specialised microorganisms to break down organic matter in wastewater. This process not only purifies the water but also converts its chemical energy into electricity. In lab tests, up to 35% of the energy stored in wastewater has been turned into power.

Since 2015, around 20–30 pilot projects have shown METs in action. A long-running plant in Sneek, Netherlands, has been operating since 2011, while others in the US, China, and South Africa have followed. One well-known example, Pee Power®, even uses urine to generate enough electricity to light toilets.

Beyond energy, METs can recover valuable nutrients like nitrogen and phosphorus. If widely adopted, these systems could meet 7% of global phosphate demand and 11% of ammonium nitrogen needs. This would help create a more sustainable circular economy by turning waste into resources.

For METs to become mainstream, they need to improve in durability, cost, and energy efficiency. Experts also call for more advocacy, funding, and economic incentives to encourage the wastewater industry to adopt the technology.

METs offer a way to turn wastewater from a burden into a source of clean energy and nutrients. With further development and support, these systems could play a key role in sustainable water and resource management. The technology is already proving itself in pilot projects—now the challenge is scaling it up.