Getting Energy From Mixing Freshwater and Seawater

Stanford researchers have developed a new battery that gets its energy from mixing freshwater and seawater also known as “blue energy“. The researchers tested a prototype battery by flushing it with alternating hourly exchanges of wastewater effluent from the Palo Alto Regional Water Quality Control Plant and seawater collected nearby from Half Moon Bay. After over 180 cycles the battery maintained a 97 percent effectiveness in capturing the gradient energy.

This technology can work anyplace that freshwater and saltwater intermix, wastewater treatment plants offer some unique opportunities. Wastewater treatment requires a lot of energy, approximately three percent of the U.S. electrical consumption. By using this new battery technology, the wastewater treatment plants would not only be energy independent but also provide essential health service in times of a power outage. It is estimated that globally wastewater treatment plants can provide about 18 gigawatts of power, that’s enough to power 15 million homes.

The battery’s large scale potential is considered far more feasible than other technologies due to its small footprint, simplicity, constant energy generation, and lack of instruments to control charge and voltage. The next step for the researchers is to see how a system performs with multiple batteries working simultaneously.

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