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Offshore wind and the wake effect

May 28, 2024 By EarthWise Leave a Comment

Electricity demand in the U.S. continues to grow and, in the summer, homes and businesses crank up their air conditioning which drives demand even further. Many East Coast cities are banking on offshore wind projects that are underway in the Atlantic Ocean to help meet that growing demand. The first offshore turbines are now producing power off the coasts of Massachusetts and New York.

Electric power utilities need to know how much power they can get from offshore wind farms, and this is not that easy to predict. Wind is variable, so there is some built-in uncertainty. But there is also a phenomenon known as the wake effect to contend with.

When wind passes through a series of giant turbines, the ones in front extract some energy from the wind and, as a result, the wind slows down and becomes more turbulent behind the turbines. So, the downstream turbines get slower wind and may produce less power.

A study by the University of Colorado has modeled this phenomenon for planned wind farms in the Atlantic Coast region and has found that power output could be reduced by over 30%. Researchers are installing weather monitors and radar sensors in islands off the New England coast to better understand the behavior of the wind in the area and improve prediction models.

The New England grid covers Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. Even with the wake effect, offshore wind is predicted to be able to provide 60% of the electricity needs of the grid, but it is important to be able to accurately predict what it can produce.

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How much energy can offshore wind farms in the US produce? New study sheds light

Photo, posted August 31, 2022, courtesy of Nina Ali via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Training Corals To Tolerate Heat | Earth Wise

April 19, 2022 By EarthWise Leave a Comment

When ocean water is too warm, corals expel the algae that lives in their tissues, which causes the coral to turn completely white. This is called coral bleaching. When this happens, the coral is not dead. However, corals are dependent upon the symbiotic relationship with algae and if conditions don’t improve, they don’t let the algae back in and the corals will die.

According to the National Oceanic and Atmospheric Administration, between 2014 and 2017, around 75% of the world’s tropical coral reefs experienced heat stress severe enough to trigger bleaching. For 30% of the world’s reefs, the heat stress was enough to kill the coral.

According to new research by the University of Miami published in the journal Coral Reefs, corals subjected to a stressful regimen of very warm water in the laboratory came to be more tolerant of high temperatures, offering a potential tool for preserving ailing coral reefs.

In the study, some corals were kept in water at a constant temperature of 82 degrees while others saw water temperatures fluctuating between 82 degrees and 88 degrees. After 90 days of this treatment, the corals exposed to variable temperatures were able to tolerate high heat for longer periods before bleaching. This training regime is akin to an athlete preparing for a race.

The findings suggest a possible approach for restoring coral reefs. Nursery-raised corals that are “trained” to tolerate heat could be planted onto reefs endangered by warming waters. Reefs populated by corals with boosted stamina to heat stress could have a greater chance of surviving the warming waters of the oceans.

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Some Corals Can Be Conditioned to Tolerate Heat, Study Finds

Photo, posted December 16, 2015, courtesy of Big Cypress National Preserve via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

More Trouble For Monarchs | Earth Wise

April 14, 2020 By EarthWise Leave a Comment

Monarch butterflies have been in trouble for quite a while and now it seems like their prospects are worse than ever. Multiple surveys of butterfly populations are reporting plummeting numbers.

Western monarch butterflies spend their winters on the central California coast. Months later, they breed in California’s Central Valley and as far north and east as Idaho. But in recent years, it has become harder and harder to find them in their breeding sites.

The Western monarch population was in the millions in the 1980s. In 2017, an annual survey found 200,000 butterflies. In 2018 and 2019, only about 30,000 butterflies were tallied. The loss of Western butterflies in general has come about from a variety of factors, including development, climate change, farming practices and the widespread use of pesticides by farmers and on home and business lawns.

Scientists use the area of land that migrating Monarchs occupy in Mexico to gauge populations. This year, they covered about 7 acres, down from 15 acres in 2019.

Meanwhile, there are also far fewer Eastern monarch butterflies on the opposite side of the country. According to a new population survey, the Eastern monarch has passed the extinction threshold. Its population in 2020 dropped 53% from its already low 2019 numbers. Scientists were expecting lower numbers this year, but they were staggered by their findings.

Butterfly populations are quite variable, so it is possible that the drastic declines this year are not necessarily irreversible, but the news is not good. Researchers and environmental advocates continue to point out that mitigating the climate crisis, reducing pesticide use and planting pollinator gardens could help the butterflies to recover.

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Web Links

Monarch Butterfly Populations Are Plummeting

Photo, posted September 7, 2017, courtesy of C. Watts via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.