VOA标准英语2015--科学家致力于提高风力发电的效率（在线收听）

Scientists Aim to Boost Efficiency of Wind Farms 科学家致力于提高风力发电的效率

Modern wind turbines usually operate in groups or so-called "wind farms," some of them with more than 100 turbines.  But the air turbulence they create decreases their overall efficiency. Scientists at Vanderbilt University are trying to solve this problem.

Wind energy is cheap and sustainable, and the number of installed wind turbines is rising everywhere in the world.

According to the U.S. Department of Energy, wind turbines now supply nearly 5 percent of electrical power in the United States.

The average efficiency of wind turbines is about 50 percent.  But because of the turbulence they create, their interactions with each other in a wind farm tends to lower that number.

Observing what they call the "conversation" of three turbines placed in a wind tunnel, scientists at Vanderbilt University in Nashville, Tennessee, are trying to find a way to reduce the adverse effects of the wake turbulences.

Engineering professor Doug Adams, the team leader, says the turbine blades are fitted with sensors.

“We use that sensor to track the motion, to do motion tracking of the blade but monitor also what we call the dynamic response.  So every time a blade moves we are monitoring it and that tells us something about that conversation that is happening from one turbine to the next,” says he.

Adams says the sensors feed data to computers, which constantly adjust the rotors' blades - compensating for the loss of energy due to the wake effect.  The benefit comes not only in increased output but also in the reduction of wear on the turbine’s mechanical parts.  Savings of only 2 to 3 cents per kilowatt hour, he says, could mean a lot for turbine operators.

“That is a game changer from the standpoint of the viability of wind energy.  It becomes absolutely competitive with the fossil fuels that we rely on today.  Without subsidies it starts to become cost-competitive,” says he.

Adams says mutually-adjustable turbines could lead to wind farms producing more energy with smaller numbers of units, while reduction of fatigue may prolong their usefulness by as much as 10 years.