Wind power is advancing at an incredible rate. Offshore wind turbines can now reach heights of over 490 feet, with blades capable of producing up to 8 megawatts (MW), which is enough to power over 4000 U.S. homes.
However, as they become more prominent, other problems arise. For example, as Atlantic hurricanes grow in strength, they threaten wind energy installations off the east coast of the United States.
A team of CU Boulder academics is following nature’s lead and flipping the turbines to improve their hurricane resistance.
Lucy Pao, the Palmer Endowed Chair in the Department of Electrical, Computer, and Energy Engineering remarked, “We are very much bio-inspired by palm trees, which can withstand these hurricane circumstances.”
Because they confront the approaching wind, traditional upwind turbines’ blades must be sufficiently rigid to avoid being thrown into the tower.
A lot of material is needed to construct the enormous and thick blades, which raises the price significantly.
Downwind rotors, on the other hand, have turbine blades that face away from the wind, reducing the chance of them colliding with the tower in high winds.
The lighter and more flexible they are, the less material they use, and thus the lower the cost of making them.
As with palm trees, these downwind blades can bend rather than break in the face of severe winds.
Pao’s team has developed the SUMR (Segmented Ultralight Morphing Rotor) turbine over the past six years in partnership with collaborators from the University of Virginia, the University of Texas at Dallas, and the Colorado School of Mines, and the National Renewable Energy Laboratory.
The results of a four-year examination of real-world data from testing their 53.38-kilowatt demonstrator (SUMR-D) at the National Renewable Energy Laboratory’s (NREL) Flatirons Campus, located south of Boulder, Colorado, were presented by CU researchers in June 10 at the American Control Conference.
During high wind gusts, their turbine performed consistently and effectively, which was a positive outcome.
“To align with the wind loads, the blades are made to be light and flexible. Because we can save money by cutting down on the cost of both the blades and the energy they use, we can do so. “Mandar Phadnis, a graduate electrical, computer, and energy engineering student, is the lead author of the new paper in the Proceedings of the 2022 American Control Conference.
It couldn’t have come at a better time for this groundbreaking effort.
According to NOAA’s Climate Prediction Center, there might be up to six major hurricanes in the Atlantic this year, with winds of at least 111mph expected between June 1 and November 30.
If there is not enough or too much wind simultaneously, wind energy generating can be challenging.
Wind turbines can’t produce a proper amount of energy when the wind speeds are too low.
Gusts that are too quick can cause turbines to shut down to avoid overheating the system.
Wind energy has been plagued from its inception by the irregularity of wind speed; the time spent shutting down the system results in less energy generated and less efficient production.
The controller, the element of the turbine that regulates when to be more or less aggressive in power output, is critical to Pao’s creative contributions.
According to Pao, the study’s principal author and a fellow at the Renewable and Sustainable Energy Institute, “We prefer to think of controllers as essentially the brains of the system” (RASEI).
Thanks to a concealed brain, wind energy can be generated at a low cost and with less wear and tear.
According to Pao, the feedback controller uses measurements of the system’s performance and makes adjustments to improve it.
To ensure that the turbine points in the right direction, yaw controllers, blade pitch controllers, and generator torque controllers all work together to determine how much electricity to draw from the turbine and into the grid.
This software algorithm directs the turbine’s motors what to do, even though it controls the turbine’s physical components.
Additionally, Pao’s team is working on the turbine’s software to ensure that it can continue to operate during high wind occurrences even if it is turned around.
To lessen the effects of peak wind gusts, Phadnis’ research aims to predict the likelihood or the probability of peak wind gusts occurring and then act before they occur.
When it comes to testing this in action, NREL’s Flatirons Campus in Boulder, Colorado, is well situated to receive the strong winds that pour across Highway 93 and onto the mesa from Eldorado Canyon directly to the west.
Despite thorough experimental testing, researchers found that their operational controller could not maintain turbine operation even at the highest generating speeds.
Additionally, Pao and her team have been collaborating with the University of Oldenburg in Germany to evaluate the usability of sensors that scan ahead of the turbine to gauge the incoming winds and improved controllers that direct the turbine to respond promptly.
Even though downwind or two-bladed turbines like the SUMR-D may not become the norm in the wind energy business, researchers can better grasp what might be achievable by conducting long-term, real-world studies, said Pao.
Traditional three-bladed, upwind turbines, which currently dominate both land and offshore markets, could potentially benefit from the control algorithms they’ve created.
According to Pao, “The advantage of the downwind layout, however, really comes into play when you get to extreme large turbines, and those are mostly for offshore,”
The group led by Pao is already aiming toward these lofty goals: SUMR (downwind) turbines of 25 and 50 MW have been constructed and modeled by their collaborators but have not been tested experimentally.
As a result, she thinks that a combination of better controllers, lighter and more resilient materials, and clever turbine layouts could allow giant offshore turbines to beat the competition in terms of performance.
One giant turbine instead of several smaller turbines (which would minimize installation and maintenance costs) and the ability to catch faster wind speeds higher off the ground are only some of the advantages of these turbines. They can also resist more severe weather.
Our revolutionary concept blades are designed to last at least 20 years, just as wind turbine blades, says Pao.
The National Renewable Energy Laboratory (NREL) and the U.S. Department of Energy’s Advanced Research Projects Agency-Energy (ARPA-E) jointly financed this research (NREL).