SNIPPETS.

SNIPPETS.

Good or bad? Turbulence from wind turbines could affect the growth of surrounding crops, researchers say.Wind farms could harm crops

While harnessing wind energy could satisfy growing demand for electricity and reduce emissions of greenhouse gases, turbulence from wind turbines could affect the growth of surrounding crops, US researchers said. Led by atmospheric sciences professor at University of Illinois, Somnath Baidya Roy, the researchers suggest careful placement of wind farms. Roy had first described the local climate impact of wind farms in 2004. The study was based on models because little data on temperatures at wind farms was available in the public domain. In 2009, Roy met Neil Kelley, meteorologist at the National Renewable Energy Laboratory in Colorado, who had collected temperature data at a wind farm in the foothills of the San Jacinto mountains in California for seven weeks in 1989.

Roy and his team analysed Kelley’s data and found the area surrounding turbines was up to 3.5 degrees C cooler during the day and up to 0.61 degrees C warmer at night than the rest of the region. Turbulent mixing brings cold air down and takes warm air up, leading to a cooler surface and vice versa. This creates a stronger mixing of heat and moisture, which causes the land surface to become warmer and drier at night, the researcher noted in the Proceedings of the National Academy of Sciences. This change can affect the growth of crops within the wind farm because warm temperature at night robs plants of moisture, Roy said. He proposed strategies to reduce the impact of wind turbines on local weather and thus the crops. Roy is mapping the wind’s frictional dissipation around the world. It shows large parts of North and central America, southern tip of South America, northern Europe, Russia, northern China, the Rift Valley and southern parts of Africa and southern Australia are ideal for low-impact wind farms.

Tiasa Adhya
Down To Earth Feature Service


Plants soak in 36 pc more VOCs than thought

Plants soak more atmospheric pollutants than thought. A study by US scientists shows that apart from carbon dioxide, plants rid the air of volatile organic compounds, or VOCs, the most abundant class of carbon-based chemicals in the atmosphere.

Automobile exhaust, coal burning and industry are some of the major sources of VOCs that cause respiratory diseases. “VOCs also combine with oxygen to form tiny airborne particles called oxygenated VOCs, which insulate the atmosphere. Karl and his team measured the level of VOCs in the atmosphere at six different places across the North and South Americas representing different ecosystems. Three of them represented tropical rainforests and the others were temperate deciduous forest, mixed temperate forest and semi-arid shrub land.

Scientists analysed field data and found, on an average, ecosystems across the globe absorb 36 per cent more VOCs than thought. The process occurs at an optimum rate in thick tropical forests and is the lowest in semi-arid shrub, the scientists noted in the Science Express, a few months back. The finding provides a platform for better climate models, Karl said.

Manupriya
Down To Earth Feature Service