Researchers in Texas discovered something unusual about three wind turbines standing together.
They each generate electricity by turning into the wind.
The team found that one turbine can affect another’s performance. It does this by creating a “wake” or “wind shadow.”
As a turbine spins, it leaves behind slower, more turbulent air. That reduces the performance of turbines farther downwind.
Researchers believe there may be a way to reduce these losses.
The approach, however, is very different from what most people would expect.
The invisible trail behind every turbine
Wind farms are built to capture as much wind as possible.
However, wind turbines don’t function individually; they interact and modify the airflow around themselves.
Researchers call these modified airflows wakes. They contain slower-moving air and greater turbulence.
That can reduce the performance of a downwind turbine.
These negative effects extend beyond decreased power output.
The uneven airflow can also add stress to various components of the downwind turbine. As a result, researchers have studied wake behavior for more than two decades.
During the study, researchers collected precise data on airflow patterns, turbine performance, and meteorological factors.
Rather than improving individual turbines, the research focused on understanding how entire wind plants operate. Their goal was to understand how entire wind plants behave as interconnected systems.
They also wanted to determine whether specific control techniques could optimize total system performance.
The objective was to improve the entire wind plant rather than optimizing individual machines. The results improved understanding of wind flow, turbulence, and how turbines interact with one another.
That knowledge could help guide the future design of both wind farms and individual turbines.
Thinking beyond a single turbine
Sandia National Laboratories created the Scaled Wind Farm Technology Facility (SWiFT), which has operated since 2011 in Lubbock.
According to Sandia National Laboratories, the facility was developed to improve the understanding of how wind turbines interact within an operating wind farm.
The facility allows researchers to study interactions between individual turbines and large-scale wind farms. Included within SWiFT are three small-scale research wind turbines.
Each was designed to measure how one turbine’s movement affects the others and how wind farms can become more efficient.
Understanding how turbines affect one another could increase electricity production across entire wind farms. That would also improve the amount of electricity generated for every dollar invested in new wind farms.
Even small efficiency gains could have a significant impact across large wind farms.
Wind farms naturally lose efficiency because of interactions between individual turbines. Those inefficiencies are magnified when they occur on tens of thousands of acres with many turbines.
Efficiency gains of just a few percent per turbine could have a significant impact across a large wind farm.
In recent years, researchers have started to study turbines in a multi-unit context instead of as independent power generation devices.
The U.S. Department of Energy continues funding research aimed at improving the performance and efficiency of wind energy.
Turning away from the wind
The turbines are not physically rotating backward.
Instead, researchers deliberately rotate certain upstream turbines slightly off-axis relative to the prevailing wind direction.
Researchers call this wake steering.
Redirecting the wind
Typically, each turbine is positioned directly into the path of maximum available wind energy, so it produces the greatest amount of electricity.
Wake steering involves adjusting the turbine slightly away from the prevailing wind direction instead of pointing it directly into the wind. This redirects the wake away from the downstream turbine, allowing it to receive cleaner, faster-moving air.
As a result, the downstream turbine receives more high-energy airflow.
It can then generate substantially more electricity than it did before wake steering was implemented.
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