A student at the University of Nebraska-Lincoln has his sights set on improving the efficiency of wind turbines.
Jie Cheng, a Ph.D. candidate in electrical engineering, has developed a system that captures and stores wasted energy for later use.
Today’s wind turbines capture only about 60 percent of kinetic energy that passes through the blades, and once the wind speed threshold is reached the turbines’ blades automatically angle to avoid damage and maintain optimal power output. The lost wind energy, “mechanical spillage,” equates to an inefficient system.
"The biggest problem for wind energy is that it's not a reliable energy resource," said Cheng. "Even if there's not enough wind to generate electricity, the community still needs it. If we can (scale up) this system, it could improve reliability by producing electricity even when there's no wind."
Cheng’s system captures and stores the spillage in an air compression tank until the wind speed drops below the threshold and the turbine returns to normal operations. The stored energy is then converted to electricity.
Using historical wind data from rural Nebraska, Cheng recently compared the performance of his prototype with a conventional wind turbine. The study found a 250-kW system would generate an extra 3,830 kilowatt hours (kWh) of electricity a week – about 16,400 extra kWh a month. That would account for more than 18 times the monthly consumption of an average American household.
Cheng’s study, authored with adviser Fred Choobineh, was published in the Journal of Power and Energy Engineering. He is now working with the university and industry partners to get the system on the market.