Prototype system transforms urine into photo voltaic powered fertilizer and clear water
by Clarence Oxford
Los Angeles CA (SPX) Aug 21, 2025
A Stanford-led staff has developed a prototype that converts urine into fertilizer whereas additionally producing electrical energy and enhancing sanitation. The system, detailed in Nature Water, recovers ammonia utilizing solar energy and captured waste warmth, providing a decentralized resolution for agriculture and vitality in resource-limited areas.
“This venture is about turning a waste downside right into a useful resource alternative,” stated senior writer William Tarpeh, assistant professor of chemical engineering. “With this technique, we’re capturing vitamins that will in any other case be flushed away or trigger environmental injury and turning them into one thing valuable-fertilizer for crops-and doing it without having entry to an influence grid.”
Nitrogen, a necessary fertilizer part, is often manufactured by way of energy-intensive processes concentrated in rich nations, leaving growing areas depending on expensive imports. Human urine comprises nitrogen equal to 14% of world annual fertilizer demand.
The prototype separates ammonia from urine by way of membrane chambers powered by solar-generated electrical energy. Waste warmth from photo voltaic panels, collected by way of copper tubing, accelerates ammonia fuel manufacturing whereas cooling panels to spice up effectivity. The system captures the ammonia as ammonium sulfate, a extensively used fertilizer.
“Every individual produces sufficient nitrogen of their urine to fertilize a backyard, however a lot of the world is reliant on costly imported fertilizers as an alternative,” stated lead writer Orisa Coombs, a Stanford Ph.D. scholar. “You do not want a large chemical plant or perhaps a wall socket. With sufficient sunshine, you’ll be able to produce fertilizer proper the place it is wanted, and doubtlessly even retailer or promote extra electrical energy.”
Integrating photo voltaic waste warmth boosted energy output by almost 60% and improved ammonia restoration effectivity by greater than 20% in comparison with earlier designs. The staff’s mannequin exhibits the system may yield as much as $4.13 per kilogram of nitrogen recovered in areas like Uganda, the place fertilizer prices are excessive and vitality entry is restricted.
The researchers are growing a bigger model with 3 times the reactor capability. Past useful resource restoration, the system additionally enhances sanitation, eradicating nitrogen that in any other case pollutes waterways and contributes to oxygen-depleting algal blooms. With over 80% of world wastewater untreated, the method may benefit communities missing sewage infrastructure.
“We regularly consider water, meals, and vitality as fully separate programs, however that is a type of uncommon instances the place engineering innovation might help resolve a number of issues directly,” stated Coombs. “It is clear, it is scalable, and it is actually powered by the solar.”
Analysis Report:Prototyping and modelling a photovoltaic-thermal electrochemical stripping system for distributed urine nitrogen recovery
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