Researchers at the University of California – Santa Cruz (UCSC) have developed a new device that harnesses sunlight and sewage to produce hydrogen fuel. The device, called a “solar-microbial device,” combines two common ways of producing hydrogen gas—using a microbial fuel cell or using a type of solar cell—to make the whole process more efficient.

In the new device, the microbial fuel cell component generates electricity from bacteria. It is this extra electricity that is used to help the solar cell—called the photoelectrochemical cell, or PEC—split water into its molecular components: hydrogen and oxygen. The process is much more efficient than using either method on its own.

The research team at the UCSC tested their device using untreated municipal wastewater from the Livermore Water Reclamation Plant. Wastewater from the plant contained both rich organic nutrients and a diverse mix of microbes that feed on those nutrients, including naturally occurring strains of electrogenic bacteria. In the microbial fuel cell, these bacteria feed on the organic matter in the waste, and produce electrons. These electrons, in turn, supply electricity to the PEC component of the device, which uses electrolysis to produce hydrogen.

“The only energy sources are wastewater and sunlight,” said Yat Li, associate professor of chemistry at the UCSC and the head of the research team. “The successful demonstration of such a self-biased, sustainable microbial device for hydrogen generation could provide a new solution that can simultaneously address the need for wastewater treatment and the increasing demand for clean energy.”

The device will continue to be tested at the Livermore Water Reclamation Plant.

“THE MFC [microbial fuel cell] will be integrated with the existing pipelines of the plant for continuous wastewater feeding, and the PEC [photoelectric cell] will be set up outdoors to receive natural solar illumination,” said Lawrence Livermore National Laboratory researcher Fang Qian.

The new device is featured in a paper published in the American Chemical Society journal, ACS Nano. (For an abstract of the paper, click here.) The first co-authors of the paper are Fang Qian and Hanyu Wang, a graduate student in Li’s lab at UC Santa Cruz. Other co-authors of the paper include UCSC graduate student Gongming Wiang, LLNL researcher Yongqin Jiao, and Zhen He of Virginia Polytechnic Institute & State University. Their research was supported by the National Science Foundation and the U.S. Department of Energy.

Hanyu Wang

Hanyu Wang, a graduate student in Li’s lab at the UCSC, helped to develop a new solar-microbial device that can use wastewater and sunlight to efficiently produce hydrogen fuel. Credit: Song Yang/UC Santa Cruz.

PEC-MFC

Pictured above is the new solar-microbial device that converts wastewater and sunlight into hydrogen. The device was developed by a team of researchers at the University of California – Santa Cruz. Credit: Song Yang/UC Santa Cruz.




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