Of the six cities studied by Indian Institute of Technology, Bombay researchers, Chennai and Mumbai seem to have the highest potential to harvest wind energy during the time when the wind energy potential is very high (active period) during the monsoon period. Compared with these two cities, Indore, Ahmedabad and Kolkata have less potential to harvest wind energy; Delhi has the least potential. The results were published in the journal Meteorology and Atmospheric Physics.
The researchers studied the strength of southwest wind during the time of the monsoon and called the period when the wind energy potential is high, the active period and the period when the wind energy potential is low, the break period. The high wind energy potential during the active period also coincides with more rainfall; there is less rainfall and less wind energy potential during the break period.
“The idea behind the study was know what the implications of the active and break periods would have on energy demand scenario in the major cities,” says Prof. Subimal Ghosh from the Department of Civil Engineering, IIT Bombay, and one of the authors of the paper.
“We have not studied the impact of climate change on wind power in the six cities. Though we have studied both active and break periods, the focus of the work was on studying the impact of dry spells [break periods] during the monsoon on energy demand-supply,” says Prof. M.C. Deo from the Department of Civil Engineering, IIT Bombay, and one of the authors of the paper. “Our study tries to answer the question if possible extraction of wind energy in the six cities can be relied on to meet the additional power demand during prolonged dry spells in the monsoon season.”
“Amongst the six cities we have considered, Mumbai and Chennai have high wind energy potential, as there is strong wind because of their coastal location. Wind energy extraction in these two cities can be of great help in meeting the gap between power demand and supply from conventional sources. The cities of Indore, Delhi and Ahmedabad do not have this advantage and hence would be unable to meet such gap in demand-supply during the dry spells in monsoon,” says Prof. Deo.
Mumbai and Chennai have predominantly higher-than-average wind energy potential during the active period compared with the break periods. “Being coastline cities, the surface drag exerted in the wind flow is the least. Also, these two cities are predominantly closer to the onset locations of southwest monsoon winds. So the prospects at these two cities are brighter,” says Sumeet Kulkarni from the Department of Civil Engineering, IIT Bombay, and the first author of the paper.
In the case of Delhi, besides that the likelihood of wind energy potential being above average is much less, a large number of high-rise buildings further dampens the prospects of efficient wind energy extraction.
It was observed that wind energy supply in north and south India has an opposing relation during the active and break periods.
For instance, during active phases, when the expected mean temperature is on the lower side, vigorous convection across central India is associated with strong winds across south India, including Chennai and Mumbai. “But in north India, the active period is marked by lower wind speed. So the wind-power potential is less during the active period,” Mr Kulkarni says.
When south India experiences less southwest winds during the break period, convective currents seen in north India bring in higher winds across northwest India. “This results in higher wind energy capacity across north India, including Delhi,” he says.
Though the wind speed is much higher in north India compared with south India during the break period, the wind energy cannot fully meet the energy demand in Delhi and Ahmedabad as the temperature is higher.
On the whole, the wind energy potential during summer monsoon (both active and break periods) makes wind energy potential unpredictable or uncertain. “But there is no significant change in the future wind energy potential across the country when the wind energy from the Arabian Sea is taken into consideration,” he says.
“Since wind energy is high during the active period and low during the break period, a proper energy management policy is important. It would be prudent to rely more on wind energy during the active period and look for alternative energy sources during the break period. This way there can be maximum utilisation of green energy,” says Prof. Ghosh.
