(Press-News.org) LAWRENCE -- Renewable wind energy is experiencing a boom, with more wind turbines popping up across landscapes in the U.S. and abroad. Indeed, wind energy accounted for 3.3 percent of electricity generation in the United States in 2011, according to the U.S. Energy Information Administration. Globally, that number was 2.9 percent for the same year.
But as wind turbines proliferate, researchers at the University of Kansas are looking at how these forests of turbines affect the wind itself. What happens to the wind when a larger number of wind turbines removes more and more of the energy of atmospheric motion?
Atmospheric science professors Nate Brunsell and David Mechem in KU's Department of Geography are co-authors of a new study just published in the Proceedings of the National Academy of Sciences by an international research group that evaluated the effects of large wind farms on atmospheric flow and its implications for how much renewable energy the turbines can generate.
"Wind turbines generate electricity by removing energy from the wind, so a larger number of wind turbines should result in a slowdown of the winds in the lower atmosphere," Mechem said.
The researchers quantified this phenomenon in numerical simulations by applying a sophisticated model normally used for weather forecasting to one of the windiest regions of the United States.
The team found that a slowdown effect triggered by wind turbines is substantial for large wind farms and results in proportionally less renewable energy generated for each turbine versus the energy that would be generated from an isolated wind turbine.
While the researchers stress that no current or planned wind farm approaches the size or concentration that would cause the slowdown effect, their results suggest the phenomenon tied to large wind farms needs to be accounted for in future planning of wind energy.
"When just a few wind turbines are installed, each additional turbine results in a similar increase in electricity generated, as you might expect," Brunsell said.
However, when a substantial number of turbines are installed over a small area, the amount of electricity generated is no longer governed by simple multiplication, according to the researchers.
"Instead, because the turbines extract energy from the wind, additional turbines will each generate less and less electricity," Mechem said.
The team's simulations estimate this slowdown effect results in a practical upper limit of 1 megawatt per square kilometer that can be generated -- far less than previous estimates not accounting for the effect. Current wind farms are operating well below this generation limit, but the authors found that this slowdown effect needs to be accounted for, particularly when comparing different sources of renewable energy.
The study was published online in the scientific journal Proceedings of the National Academy of Sciences on Aug. 24.
INFORMATION:
NASA's Aqua satellite passed over Hurricane Ignacio and viewed the storm in infrared light, providing valuable temperature data. Aqua saw a weaker Ignacio moving parallel to the Hawaiian Islands.
The Atmospheric Infrared Sounder or AIRS instrument aboard Aqua gathers infrared data that shows temperatures. That AIRS data was made into a false-colored infrared image from August 30 at 22:47 UTC (6:47 p.m. EDT) and showed high, cold, strong thunderstorms surrounded the center of Hurricane Ignacio.
AIRS imagery also showed a thick band of thunderstorms spiraling into the ...
Researchers link babies' performance on cognitive tasks to later learning progress
Study underscores importance of talking to your baby well before they can talk back
Findings may eventually contribute to reducing "vocabulary gap"
EVANSTON, Ill. --- At 12 months old, your infant's ability to group objects according to the names associated with them -- as opposed to their appearance alone -- offers a glimpse into how his or her vocabulary will develop by the time they are 18 months, Northwestern University researchers have found.
The research, by Brock Ferguson, ...
This news release is available in Spanish. Marine energy has a great future potential according to the experts, but there is still a long way to go before it can be used on a large scale. Despite the problem of intermittency, wave energy has an advantage over wind energy, for example: it is easier to predict optimum swell than some suitable gusts of wind. That is why knowing how much energy the waves will be bringing within a few hours is as important as having available efficient prototypes to make use of wave power. If this information is known, the energy produced ...
PITTSBURGH, Aug. 31, 2015 -- People with hostile personality traits who watch more television than their peers may be at a greater risk for injury, potentially because they are more susceptible to the influence of television on violence and risk-taking behaviors, a University of Pittsburgh Graduate School of Public Health analysis discovered.
The research, published online in the International Journal of Injury Control and Safety Promotion, suggests that a reduction in television viewing and content rating systems geared not just to age, but also personality traits, ...
Life on an island isn't always easy. To make the most of the little there is to eat on many Greek islands, the digestive system of Balkan green lizards has evolved considerably compared to family members on the mainland. Surprisingly, many of these insect-eating lizards even have special valves that help to digest plants. These are some of the findings¹ from a study led by Konstantinos Sagonas of the National and Kapodistrian University of Athens in Greece, published in Springer's journal The Science of Nature².
Reptiles can adjust their digestive system and ...
PITTSBURGH, Aug. 31, 2015 -- The more hours young adults spend watching television each day, the greater the likelihood that they'll have a higher body mass index and bigger waist circumference, a 15-year analysis by the University of Pittsburgh Graduate School of Public Health revealed.
The association did not hold in later years, indicating that young adulthood is an important time to intervene and promote less television viewing, according to the research published online in the journal SAGE Open.
"We were quite surprised to find that television viewing was associated ...
ROCHESTER Minn. -- A team of Mayo Clinic Cancer Center scientists has been awarded a Specialized Program of Research Excellence (SPORE) grant in multiple myeloma from the National Cancer Institute. The Mayo Clinic Cancer Center is one of only three cancer centers to receive a SPORE grant for multiple myeloma cancer research.
MULTIMEDIA ALERT: Video and audio are available for download on the Mayo Clinic News Network.
"With project leaders from Mayo campuses in Arizona, Rochester and Florida, our SPORE team will study the genetic basis for myeloma, develop novel viral ...
Satellite data from NOAA's GOES-East satellite was made into an animation that showed the demise of former Tropical Storm Erika as it neared eastern Cuba early on August 29.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland, NASA/NOAA's GOES Project compiled three days' worth of imagery from NOAA's GOES-East satellite that showed the movement and changes in former Tropical Storm Erika from August 27 to August 29. The animation showed Erika move through the Leeward Islands and into the Eastern Caribbean Sea, as its center passed just south of Puerto Rico, then ...
London, UK - 30 Aug 2015: Recruitment of leukocytes is a hallmark of stent thrombosis, according to results from the PRESTIGE study presented today at ESC Congress1 and published in European Heart Journal.2 The findings suggest that immune cell mediated thrombotic processes may be a realistic target for novel therapies to prevent stent thrombosis.
"Stent thrombosis (ST) is a life-threatening complication of percutaneous coronary intervention and recent large scale clinical registries reported an incidence of up to 0.4-0.6% per year," said principal investigator Professor ...
How did the ankylosaur get its tail club? According to research from North Carolina State University and the North Carolina Museum of Natural Sciences that traces the evolution of the ankylosaur's distinctive tail, the handle arrived first on the scene, and the knot at the end of the tail followed.
The typical ankylosaur had a wide armored body and a flexible tail. But one group of ankylosaurs - ankylosaurids - also had a tail club that could have served as a useful weapon. These "weaponized" ankylosaurids lived about 66 million years ago, during the Cretaceous period. ...
