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Cambridge Institute for Sustainability Leadership

June 2019: Scientists have found a promising new way of using wastewater and sunlight to produce hydrogen. The technology almost doubles the efficient rate of ‘splitting’ water and delivers encouraging results for industrial scale application.


Researchers at Princeton University have found a promising new way to produce hydrogen from wastewater using sunlight. They designed a modular chamber with a black silicon interface to convert wastewater from breweries into water and hydrogen. It uses energy generated by bacteria consuming organic matter in the wastewater, resulting in a process that almost doubles the splitting process’ efficiency rate.

Implications & Opportunities

This new could lead to a less energy intensive and cheaper method of producing hydrogen, while also cleaning wastewater. Using the modular chambers and wastewater allows for easier scalability and could deliver the co-benefits of treating and re-using wastewater while generating large amounts of hydrogen for energy consumption. Against this backdrop, the technology could especially appeal to refineries and chemical plants that consume large amounts of energy, and face high costs for cleaning wastewater.


The technology remains untested for wastewaters other than from breweries and has not yet been applied beyond the laboratory scale. Further, the researchers produced hydrogen over four days, requiring further long-term experiments to test the technology’s feasibility and full lifecycle impacts.


Lu, L., Vakki, W., Aguiar, J. A., Xiao, C., Hurst, K., Fairchild, M., … Ren, Z. J. (2019). Unbiased solar H2 production with current density up to 23 mA/cm2 by swiss-cheese black Si coupled with wastewater bioanode. Energy & Environmental Science, 12 (3). doi:10.1039/c8ee03673j 

The Engineer. 2019. Princeton team makes hydrogen from wastewater. Retrieved from