Renewable energy is transforming globally and at an unparalleled scale. India, being the fifth largest producer of wind energy in the world, is in the forefront of shifting toward renewable energies with a cumulative installed capacity of over 19,000 MW.
While India already has inland wind farms in Tamil Nadu, Karnataka, Gujarat, Maharashtra, Rajasthan, Madhya Pradesh, Telangana and Andhra Pradesh, it is now looking at establishing wind farms in the sea, which also called offshore wind farms.
In recent years, India has been experiencing monsoons with high magnitudes of variability, in the form of extreme rainfall spells known as active (heavy rainfall) and break (low rainfall) spells. Changes in the occurrence of summer monsoons are significantly associated with southwest monsoon wind, which forms a major component of extractable wind energy potential.
The researchers from the Indian Institute of Technology, Bombay (IIT-B) assessed the strength of southwest monsoon wind flowing across the Arabian Sea. The prolonged period of stronger wind in a monsoon was denoted as an ‘active spell’ and periods with low wind magnitude as a ‘break spell’. The active spell coincided with more rainfall and reduced temperature; whereas, break spells in scanty rainfall were associated with soaring temperatures.
Dr. Sumeet Kulkarni, the first author of the study states, “When break spells occur, the ambient temperature rises, resulting in higher power demand for agricultural activities such as pumping, mechanization, and use of fertilizers for optimum agricultural productivity. In addition, the electricity demand in urban areas for cooling purposes such as air-conditioning also aggravates during drought (break) periods. Whereas during the wet periods such demand reduces, although at the same time the power supply increases because of strong westerly winds contributing to an enhanced production of wind energy. At this backdrop, our research aims to understand whether the energy supply from offshore wind farms can partially or fully cater to these fluctuations in power demand.”
Summarizing the outcomes, he says, “From our study, an encouraging observation for the wind industry is that although the annual summer rainfall trend, in past thirty years is significantly decreasing, the monsoon wind trend is not largely affected. In future three decades the annual average wind potential in monsoon is expected to range from (270 to 275 W/m2) which is substantial.”
Amongst several causes for changes in rainfall patterns in India, recent studies show that El-Nino’s impact is predominant. “In the past three decades El-Nino has had a suppressing effect on monsoon wind circulation patterns and hence its future assessment becomes vital. Our study concluded that such suppressive power is getting reduced after the year 2000, which again is a positive aspect for the wind industry,” adds Dr. Kulkarni.
In the next part of the study, the authors evaluated whether the current availability of wind energy potential can be relied upon to meet power deficits during prolonged break spells in the following six Indian metropolitan cities: Delhi, Ahmadabad, Mumbai, Indore, Chennai, and Kolkata.
“Amongst the six cities under consideration, the coastal cities of Chennai and Mumbai have highest wind power potential. The surface drag exerted on the flow of wind is minimal across the oceans in comparison to the urban areas. As these two cities are in the vicinity to the onset locations of southwest monsoon winds, the prospects for these two cities are brighter. Whereas the residual power demand (shortage of power) in Delhi, Indore, and Ahmadabad is expected to be the highest and hence it is anticipated that these cities would be unable to meet the gap between power demand and supply from conventional sources, during the dry spells in monsoon.”
“Keeping in view that wind energy is highly fluctuating during the active and break phases period, it is important to frame a wind energy management policy. The utilization of green energy can be maximized by capitalizing on the extraction during active phases and using alternative energy sources during the break period to cater the net demand deficit of power,” concludes Dr. Kulkarni.
These findings are described in the article entitled “Impact of active and break wind spells on the demand-supply balance in wind energy in India“, recently published in the journal Meteorology and Atmospheric Physics. This work was conducted by Sumeet Kulkarni, M. C. Deo, and Subimal Ghosh from the Indian Institute of Technology, Bombay, India.