Prototype system transforms urine into solar energy driven fertilizer and clean water
A Team led by Stanford has developed a prototype that converts urine into fertilizers while also electricity is generated and the sanitary facilities improves. The system, detailed in natural water, restores ammonia with the help of solar energy and conquered waste heat and offers a decentralized solution for agriculture and energy in areas with limited resources.
“This project is about converting a waste problem into an opportunity for resources,” says senior author William Tarpeh, university professor of chemical engineering. “With this system we capture nutrients that would otherwise be washed away or cause environmental damage and convert them into something valuable fertilizer for crops or without having access to a power grid.”
Nitrogen, an essential component for fertilizers, is usually manufactured by energy-intensive processes concentrated in rich countries, so that development regions depend on expensive imports. Human urine contains nitrogen equivalent to 14% of the worldwide annual demand for fertilizers.
The prototype separates ammonia from urine by membrane rooms powered by electricity generated by solar energy. Waste heat from solar panels, collected via copper hose, speeds up the production of ammoniagastang while cooling panels to increase efficiency. The system catches the ammonia as an ammonium sulfate, a commonly used fertilizer.
“Every person produces enough nitrogen in his urine to fertilize a garden, but a large part of the world depends on expensive imported fertilizers instead,” said Chief Authory Orisa Coombs, a Stanford Ph.D. student. “You do not need a huge chemical plant or even a wall connection. With sufficient sunshine you can produce fertilizer where it is needed and possibly even store or sell excess electricity.”
Integration of solar waste heat stimulated the power by almost 60% and improved ammonia recovery efficiency by more than 20% compared to earlier designs. The model of the team shows that the system can yield up to $ 4.13 per kilogram of nitrogen that is found in regions such as Uganda, where the costs of fertilizer are high and the access of energy is limited.
The researchers develop a larger version with three times the reactor capacity. In addition to the restoration of resources, the system also improves the sanitary facilities, the removal of nitrogen that contaminates waterways and contributes to oxygen breakdown algae blooms. With more than 80% of the global waste water untreated, the approach could go to communities without sewerage infrastructure.
“We often consider water, food and energy as fully separate systems, but this is one of those rare cases in which engineering innovation can help solve several problems at the same time,” Coombs said. “It is clean, it is scalable and it is literally powered by the sun.”
Research report:Prototyping and modeling of a photovoltaic thermal electrochemical comic strip system for distributed urine rough repair recovery
