May 11, 2009 Clean, renewable energy is freely available – in the form of wind, sun and water. However, harnessing it reliably and cost-effectively remains a barrier. Wind power is one of the fastest growing alternative energy markets and researchers at Purdue University and Sandia National Laboratories in West Lafayette, Indiana, are working to make wind turbines more efficient, reliable and resilient.

They are using sensors and computational software that constantly monitor forces exerted on wind turbine blades with the aim of developing a smarter wind turbine structure.

Improving reliability and resilience

"Our aim is to do two things: improve reliability and prevent failure. The most direct way to enable those two capabilities is by monitoring forces exerted on the blades by winds," says Douglas Adams, a professor of mechanical engineering and director of Purdue's Center for Systems Integrity.

According to doctoral student Jonathan White, who is working on the project with Adams, “the ultimate goal is to feed information from sensors into an active control system that precisely adjusts components to optimize efficiency."

One of the main problems with wind turbines is that the wind can suddenly change direction and force, decreasing efficiency and causing costly damage to blades. The team from Purdue and Sandia believes its technique can help prevent this by providing real-time information to the turbine’s control system and predicting fatigue.

Sensors were embedded in the turbine blade as it was being built. Testing on a research wind turbine in Texas has shown that using a trio of sensors and "estimator model" software accurately reveal how much force is being exerted on the blades.

In the future, turbine blades could be fitted with flaps like those on an airplane’s wings. Sensors inside the blades would enable blade pitch to be adjusted in real time to respond to changing conditions.

"Wind energy is playing an increasing role in providing electrical power," says Adams. "The United States is now the largest harvester of wind energy in the world. The question is, what can be done to wind turbines to make them more efficient, more cost-effective and more reliable?"

Alternative energy is big business

The Renewable Energy: Global Industry Guide put the value of the renewables market at USD$246 million in 2007, and there’s no shortage of companies trying to improve on existing technologies and share the profits. Catch the Wind is a Virginia-based company that has developed a fibre optic laser sensor, the Vindicator. It sits atop turbines and measures wind data in real time, allowing adjustments to be made to the turbine well before the wind comes. The company’s research suggests it can provide an increase of up to a 10 percent in turbine output power.

The Leviathan Wind Energizer claims to increase power output by between 15 percent and 30 percent, when the turbine is spinning. It uses aerodynamic modeling to direct the surrounding wind flow to the critical area of the blades, via a passive structure located near each of the turbines.

ExRo Technologies believes its generator reduces costs and increases output by up to 50 percent because more than 90 percent of its energy can be converted into electricity. Rather than use a traditional mechanical generator to compensate for variations in the wind, they have developed a self-adapting electrical system that can scale up and down with available energy in a way that would take almost 70 traditional generators to match.

This isn't the only example that demonstrates biomimicry can provide answers. We recently covered the Tubercle Technology, a breakthrough in aerodynamic design offering more power, less noise and the ability to generate power at wind speeds that are much too slow for traditionally shaped turbines.

Karen Sprey