Princeton Engineers Pioneer Breakthrough Method for Producing Green Hydrogen from Wastewater
In a major step toward sustainable hydrogen production, researchers at Princeton University have developed a simple and cost-effective method to produce green hydrogen from wastewater, dramatically reducing both water use and treatment costs associated with clean energy generation.
The innovative approach, published September 24 in Water Research, enables hydrogen to be generated using reclaimed water instead of purified water — addressing one of the key environmental and economic challenges in the hydrogen fuel industry.
Led by Professor Z. Jason Ren, a leading expert in environmental engineering and the Andlinger Centre for Energy and the Environment, the Princeton research team discovered that adding a small amount of sulfuric acid to wastewater overcomes a long-standing obstacle: the buildup of calcium and magnesium ions that typically block electrolysers and degrade performance.
“Hydrogen infrastructure often competes with local freshwater resources,” said Professor Ren. “But every community has access to wastewater treatment plants — which means we already have a distributed, sustainable source of water for the hydrogen economy.”
Turning Dirty Water into Clean Energy
Traditional green hydrogen production relies on electrolysis — a process that splits water into hydrogen and oxygen using renewable electricity. However, this process usually requires ultrapure water, achieved through costly purification systems like reverse osmosis. As a result, hydrogen producers face high operational costs and growing pressure over water consumption, particularly in drought-prone regions.
By using treated wastewater, Ren’s team demonstrated that hydrogen could be produced efficiently without the need for expensive purification. When the researchers acidified reclaimed water with sulfuric acid, they found that the process stabilized for over 300 hours of continuous operation — maintaining strong performance without membrane clogging or system degradation.
The key lies in the chemistry: acidifying the wastewater releases protons that outcompete the mineral ions, keeping the electrolyser membrane clear and allowing steady hydrogen generation. Importantly, the acid is recirculated within the system, ensuring that it does not escape into the environment.
A Cost-Cutting, Climate-Friendly Innovation
According to the study, the new wastewater electrolysis method could reduce the cost of water treatment for hydrogen production by up to 47%, and the energy required for purification by as much as 62%.
This breakthrough has the potential to transform the economics of clean hydrogen, particularly for heavy industries such as steel, fertilizer, and transportation, where direct electrification remains difficult.
“Our method makes green hydrogen more affordable and scalable,” Ren explained. “It allows us to turn what was once waste into a valuable clean-energy resource.”
Scaling Up for a Sustainable Hydrogen Future
The Princeton team is now collaborating with industrial partners to test the technology at larger scales, including exploring applications with pretreated seawater. Their ongoing research also identifies optimal U.S. regions for collocating hydrogen production facilities with wastewater treatment plants, maximizing both cost savings and water reuse.
With this discovery, Princeton Engineering moves one step closer to realizing a national hydrogen strategy rooted in sustainability, efficiency, and environmental stewardship.
