A team of researchers led by Dr. Daniel Kwok and Dr. Larry Kostiuk in the Faculty of Engineering at the University of Alberta has discovered a new way of generating electric power from flowing water.
When a liquid such as water is passed through a small channel, a physical phenomenon called charge separation occurs. The surface of the channel becomes ionically charged and opposite-charged ions in the liquid are attracted to it.
At the same time, like-charged ions are repelled from the surface. This results in a thin liquid layer with a net charge. This region, known as the Electric Double Layer (EDL), ranges from several nanometres to a few micrometres thick.
To harness this phenomenon, the research team constructed a microchannel with a diameter similar to the EDL itself and then forced the liquid through the channel. This resulted in only one type of ion in the EDL being transported downstream, creating a current and hence a voltage difference across the ends of the channel.
An external electric circuit was constructed by placing electrodes at the ends of the channel, and electrical energy was extracted from the device as current flowed between the electrodes.
Although the power generated from a single channel was extremely small, millions of parallel channels could theoretically be used to increase the power output.
A patent application has been filed by the University to obtain broad, early protection of its invention.
The research was published yesterday by the Institute of Physics’ Journal of Micromechanics and Microengineering.