SEP 17, 2015

Doctoral Student Creates A System To Vastly Improve Wind Turbine Efficiency

WRITTEN BY: Andrew J. Dunlop

Wind turbines are great for producing clean energy, but they have two major problems. The one you may be thinking of is that it’s not windy all the time, so they can’t constantly or consistently produce power. The less well known problem for wind turbines is that in very high winds, they angle their blades to spill off a significant amount of the wind energy to keep from damaging themselves. This unfortunately means that wind turbines, on average, miss out on about 40 percent of the energy they could be generating. Je Ching, a doctoral candidate studying electrical engineering at the University of Nebraska-Lincoln may have come up with a design that could fix both of these problems.

Cheng has designed a system that can actually capture and store surplus wind energy for later use to produce electricity. In a recent study, Cheng compared his prototype's performance against a conventional wind turbines, based on historical wind data from rural Springview, Nebraska, for a week. He found that with his system attached, a 250-kilowatt wind turbine system was capable of yielding an additional 3,830 kilowatt-hours per week of electricity. That comes out to roughly 16,400 extra kilowatt-hours a month. According to the U.S. Energy Information Administration, that’s about 18 times the monthly energy use of the average American household. Cheng’s study also showed that his system would lower total energy costs slightly along with significantly reducing fluctuations in power generation.

Physicists studying conventional wind turbine designs have found that they are only capable of capturing 59.3 percent of the potential kinetic energy from the wind. This comes from the fact that they can’t produce energy when the wind isn’t strong enough, and from the fact that they spill off energy when the wind gets too strong, so as not to damage themselves.

Cheng's system directs this spillage into an air compression tank, where the excess energy that would otherwise be wasted remains, until it is needed. When wind speeds dip below the point where the turbine operating at its optimal capacity, the tank begins using its compressed air to regenerate electricity. In this way, Cheng’s system addresses both the wasted potential energy that would otherwise be wasted during strong winds and the deficit in production that turbines usually suffer during periods of low wind speeds.

"The biggest problem for wind energy, Cheng explains, “is that it's not a reliable energy resource. … 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.”

"We have a lot of wind energy here,” Cheng says, “and we live among grasslands, so there's little environmental (interference). … I see a lot of potential for this, especially in Nebraska."

Source: Phys.org