A newly developed system transforms human waste into a powerful tool for profitable and sustainable energy and agriculture in resource-limited regions.
The prototype, outlined in a Stanford-led study published in Nature Water, recovers a valuable fertilizer from urine, using solar energy that can also provide power for other uses. In the process, the system provides essential sanitation, making wastewater safer to discharge or reuse for irrigation.
"This project is about turning a waste problem into a resource opportunity," said study senior author William Tarpeh, an assistant professor of chemical engineering in the Stanford School of Engineering.
"With this system, we're capturing nutrients that would otherwise be flushed away or cause environmental damage and turning them into something valuable—fertilizer for crops—and doing it without needing access to a power grid."
Nitrogen is a key component of commercial fertilizers. Traditionally, it's produced using a carbon-intensive process and distributed globally from large industrial facilities, many of which are located in wealthier nations, resulting in higher prices in low- and middle-income countries. Globally, the nitrogen in human urine is equivalent to about 14% of annual fertilizer demand.