Poop-Powered Solar Panels Foster A Self-Renewing Hydrogen Energy Source
A new device from the University of California Santa Cruz harnesses sun and sewage to produce hydrogen fuel.
Everybody poops, and now a newly developed gadget from the University of California Santa Cruz can harness energy from that waste and combine it with solar power to create a self-sustaining source of hydrogen fuel.
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"The only energy sources are wastewater and sunlight," said senior author Dr. Yat Li, a chemist at UC Santa Cruz. "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."
This invention could be a tidy solution for many developing nations, who have sewage to spare but lack electricity. Developed countries are searching for ways to harness their sewage too, with places like New York City looking to tap energy from the billions of gallons of waste that it produces every single day.
The gadget comes with two essential features. The first is a fuel cell packed with microbes that can turn sewage into electrical energy. The other attribute is a photoelectrochemical cell, a device that collects solar power and uses it to split water molecules into oxygen and hydrogen. This hydrogen is stored away for use as a 'green' fuel source.
Prior to this work, people had tried microbial fuel cells and photoelectrochemical cell separately to produce hydrogen gas, but neither was very efficient. Both required an extra energy source for sufficient water splitting, and this drawback made their large-scale production a costly endeavor.
Dr. Li's team devised a solution where the microbial fuel cell feeds energy directly into photoelectrochemical cell, making it easier for the latter to wrest hydrogen fuel from water. This hydrogen source would be self-sustaining as long as there is sewage to feed it - rarely in short supply - and the sun is out.
The current prototype is small, but the next step is to create a 40-liter version to test with municipal water in the lab. If that works, then the team will try at a wastewater treatment plant.
"The microbial fuel cell will be integrated with the existing pipelines of the plant for continuous wastewater feeding, and the photoelectrochemical cell will be set up outdoors to receive natural solar illumination," said coauthor Fang Qian, a researcher at Lawrence Livermore National Laboratory.
"Fortunately, the Golden State is blessed with abundant sunlight that can be used for the field test," Li added.
Source: Wang H, Qian F, Wang G, Jiao Y, He Z, Li Y. Self-Biased Solar-Microbial Device for Sustainable Hydrogen Generation. ACS Nano. 2013.
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