Nov 15, 2004

http://www.keralanext.com/news/?id=65502

US News, New York - An India-born, US-based scientist has proved that large-scale installation of windmills to replace conventional sources of energy may cause drastic local weather changes.

According to a newly published study by The Journal of Geophysical Research quoted by the New York Times, a wind farm with thousands of wind turbines also removed an enormous amount of energy from the air.

The research was headed by Somnath Baidya Roy who works with Princeton University in New Jersey, along with R.L. Walko of Duke University in North Carolina and S.W. Pacala, also of Princeton University.

It showed that the movement of windmill blades led to a great amount of atmospheric mixing, causing meteorological changes.

For the study, a wind farm consisting of an array of 10,000 turbines with rotor blades 50 metres long was set up in a 97 x 97 kilometre area in north-central Oklahoma.

According to Roy, the wind farm was much larger than those that have been built so far but was similar to those being considered for more power from renewable resources.

During the course of the experiment, the turbines were seen to trap a cool nocturnal jet of air, present in the Great Plains in Oklahoma, that separated the cool moist air near the ground from the drier, warmer air above.

This, in turn, caused turbulence in the air that led to vertical mixing of the air currents.
"It is the turbulence generated by the rotor that is crucial when you talk about impact on local meteorology," Roy said.

As a result of the warming and drying of surface air that occurred in the Great Plains, there could be weather impacts similar to the kinds of local atmospheric changes that occur with large-scale deforestation.

"You might see some kind of convective clouds or scattered rainfall here and there," he said.
Roy, who was born in Kolkata, did his graduation in BSc Physics from Presidency College there and got his MSc in Environmental Science from Jawaharlal Nehru University in New Delhi. He has published many journals on atmospheric sciences, geophysical research and conservation ecology in the US.

Having worked as a research assistant for the Department of Science and Technology in New Delhi (1993) and for the Planning Commission (1994-95), Roy is now a research associate at Princeton University.

Noting that although his current study was only preliminary, he indicated a need to improve rotor design to reduce turbulence in windmills of the future