Cars powered by hydrogen fuel cells could eventually be pulling up to wastewater treatment plants for fill-ups, claim Penn State University environmental engineers.
Dr. Bruce Logan, professor of environmental engineering, and his research group have shown they can boost hydrogen production 43 percent by using a continuous hydrogen release fermentation process.
He said that by using certain industrial wastewater as feedstock, the approach offers an abundant, ‘green,’ local source for hydrogen and potentially makes it a cheaper fuel than gasoline.
‘Continuous fermentation is not hard to do and the high volumes of gas produced make it a potential source of supply for a wide variety of fuel cell applications besides cars and buses, including home power generation and the micro-fuel cells being developed for consumer products,’ Logan added.
In the Penn State experiments, fermentation was conducted with bacteria from ordinary garden soil. The soil, collected from local farmland, was heat treated to kill hydrogen-consuming bacteria. While the heat treatment also kills non-hydrogen producing soil bacteria, it leaves hydrogen-producing bacteria in a dormant spore form that revives as soon as it is put in suitable conditions.
The researchers mixed the heat-treated soil with individual samples of glucose, sucrose, cellulose, lactate, potato starch and molasses. Fermentation of both glucose and sucrose with the heat-treated soil under slightly acidic conditions in the absence of oxygen produced high concentrations of hydrogen gas.
Releasing the gas continuously during glucose processing is said to have resulted in 43 percent more hydrogen than when the gas was released intermittently.
Logan noted that wastewater from confectioners, canneries, sugar refineries, and other industries are rich in glucose and sucrose. ‘The conversion of the chemical energy in these sugars to electricity in fuel cells via hydrogen gas, provides a method for wastewater treatment and renewable energy production in one step. The greatest savings at treatment plants may result from reducing costs for aerators since aeration is the major operational expense at most wastewater treatment plants,’ said the Penn State researcher.
In addition, methane could also be generated via the same process and from the same materials to provide an additional source of clean energy for fuel cells.
‘Generating hydrogen by fermentation is not new,’ said co-researcher, Steven Van Ginkel. ‘Batch fermentation was used during World War II to produce industrial solvents for ammunition production. Small amounts of hydrogen produced early in the fermentation process were not recovered.
However, the industry later switched to steam reformation of petroleum to produce these industrial solvents when oil was cheap.
‘Now that oil has become more expensive, more efficient ways to generate hydrogen, for example the continuous fermentation processing method, may help us cross the barrier to realising hydrogen’s promise as the fuel of the future,’ he added.