Tobin makes breakthrough in wind farm efficiency

03/28/2017
 
Tobin, right, in the wind tunnel in Chamorro's lab.
Tobin, right, in the wind tunnel in Chamorro's lab.
TAM PhD candidate Nick Tobin discovered that the use of windbreaks help increase the amount of power harvested by wind farms. His research was recently published in the journal Boundary-Layer Meteorology
 
Tobin, working with his advisor, Assistant Professor Leonardo Chamorro in the Renewable Energy and Turbulent Environment lab, said his research arose from work he had done with Chamorro when they were both at the University of Minnesota (Tobin as an undergraduate and Chamorro as a post-doc). While at Minnesota, Tobin said he was looking at how the surface of the ground between wind turbines impacts the amount of power generated by those turbines. What he found was that rougher patches of ground could help wind speeds to recover quicker between turbines, since more turbulence is created to spread the turbines’ wakes.
 
“If you have a large array of wind turbines, and if you have one in front of the other, it’s going to slow down the wind for the second one, causing it to produce less power,” Tobin said. “The project that we were doing was about how the rough ground in between impacts the deficit for the second turbine.”
 
This research formed the basis of Tobin’s proposal for his National Science Foundation (NSF) fellowship. He proposed planting rows of trees as roughness elements, which are commonly used on farms to prevent soil erosion as well as to reduce the impact of wind on buildings. 
 
Using the computational resources provided by the NSF fellowship, Tobin said he used simulations to see the effect of windbreaks immediately downwind of turbines. He found, however, that the negative impact of the windbreaks slowing the wind was greater than the effect of the enhanced wake spreading. But by moving the trees to the upwind side of the turbine, the results changed. As the wind flow approached the turbines and had to go over the trees, it accelerated above the trees.
 
“We did an experimental and theoretical study on this and we found that by planting a row of trees maybe 50 meters in front of an industrial wind turbine, we could increase its power output by something like 10 percent,” said Tobin. 
 
Tobin is continuing his research to compute how large wind farms could be impacted by these windbreaks. In the long term, Tobin said he hopes to see his mechanism applied in the real world. He is in contact with a local wind farm near Bloomington, Illinois, to simulate this mechanism to conduct a design study. 
 
Furthermore, through connections that he and Chamorro have made at conferences, Tobin said he hopes there will be many advancements for this project in the future. He also wants this technology to expand to places in the United States that may not have been economical enough in the past to have a wind farm. 
 
“I hope this will lead to more wind energy production, which is important,” Tobin said. “The reason I have been doing this from the start is because I care about carbon emissions and I want to help move forward the transition to renewable energy.”