Penn State researchers are demonstrating a renewable method for hydrogen production from wastewater at the Napa Wine Company in Oakville, CA. The refrigerator-sized hydrogen generator will take winery wastewater and - using bacteria and a small amount of electrical energy - convert the organic material into hydrogen.
"This is a demonstration to prove we can continuously generate renewable hydrogen and to study the engineering factors affecting the system performance," said Bruce E. Logan, Kappe professor of Environmental Engineering. "The hydrogen produced will be vented except for a small amount that will be used in a hydrogen fuel cell." Eventually, Napa Wine Company would like to use the hydrogen to run vehicles and power systems.
The company's wastewater comes from cleaning equipment, grape disposal, wine making, and other processes. The company already has on-site wastewater treatment and recycling, and the partially treated water from the microbial electrolysis system will join other water for further treatment and use in irrigation.
Penn State's microbial electrolysis plant is a continuous flow system that will process about 1,000 liters of wastewater a day. Microbial electrolysis cells consist of two electrodes immersed in liquid. Logan uses electrode pairs consisting of one carbon anode and one stainless steel cathode in his system rather than an electrode coated with a precious metal like platinum or gold. Replacing precious metals helps keep costs down. The demonstration plant is made up of 24 modules and each module has six pairs of electrodes.
The wastewater enters the cell where naturally occurring bacteria convert the organic material into electrical current. If the voltage produced by the bacteria is slightly increased, hydrogen gas is produced electrochemically on the stainless steel cathode.
"We chose a winery because it is a natural tourist attraction," Logan explained. "People go there all the time to experience wine making and wine, and now they can also see a demonstration of how to make clean hydrogen gas from agricultural wastes."