Research: Gaps in the Indian monsoon make for tricky power balancing

renewable energyDemand for power in India is rising rapidly, driven by economic growth, rising prosperity, rapid urbanisation and growing demand for energy for cooling purposes. Some of this additional power need is being met by increasing investment in wind energy, particularly in the south and west of India. A recent analysis highlights important considerations for deploying  India’s expanding capacity in renewables in a more efficient manner to balance gaps in the annual advance of the Indian monsoon.

The seasonal cycle in India is dominated by the South Asian monsoon, a vast circulation pattern over the Indian Ocean and Indian sub-continent driven by intense heating from the Sun during northern hemisphere summer. The onset of the monsoon brings life-giving rains to support India’s population of over 1 billion people, but monsoon activity within any season system is irregular, and can be characterised into ‘active’ and ‘break’ periods. Active periods bring increased rainfall, stronger winds and lower temperatures for most of the country, while break periods are marked by reduced rainfall, higher temperatures and weaker winds. During the pre-monsoon season in 2015, for example, temperatures reached 47 °C in parts of India.

India powers up renewables
India’s total generating capacity has more than doubled since 1998, and wind power currently accounts for 8.4% of capacity: it is already the world’s fifth-largest wind energy producer, and is on target to meet 15% of its electricity requirements from renewables by 2020. “The problem arises because the higher temperatures in break periods increase power demand, mainly for air conditioning, while at the same time the production of wind energy is sharply reduced in the lighter winds which accompany break periods,” said Caroline Dunning from the University of Reading, the lead author on the recent paper in Environmental Research Letters (doi link). “The mis-match means that potential wind energy supplies are lowest, just when they are most needed.”

Current weather forecasts can provide only limited warning of an impending break, and little useful information as to its likely duration: this uncertainty forces India to retain secondary sources of power generation on short-term standby, without knowing in advance either when or for how long they will be required. Improvements in forecasting out to two weeks or more would bring significant environmental and economic benefits, as well as reducing uncertainty in day-to-day operational resource management, but are unlikely to be realised within the short term. Meanwhile, the occurrence of high temperatures during monsoon breaks has resulted in power outages in India in recent years, with both economic and social impacts.

An offshore solution?
Dunning and colleagues conclude that, “over-reliance on wind energy from southern India and along the western coast could lead to problems at times of high demand” and suggest that offshore wind turbines in the north-east Arabian Sea may reduce the imbalance, as that offshore region experiences increased wind speeds during break phases. A further complexity is the uncertain outlook projected for monsoon variability under future climate projections – as clearly any increase in the frequency or duration of monsoon breaks would exacerbate the situation further.

Dunning, C.M., Turner, A.G. and Brayshaw, D.J., 2015. The impact of monsoon intraseasonal variability on renewable power generation in India. Environ. Res. Lett., 10, 064002: doi:10.1088/1748-9326/10/6/064002 (Open Access)

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