Identifying weather patterns responsible for renewable energy variability and complementarity

Identifying weather patterns responsible for renewable energy variability and complementarity

Energy systems across the globe are evolving to meet ambitious climate mitigation targets. This process requires a rapid reduction in nations’ reliance on fossil fuels and a significant uptake of renewable generation, such as wind power, solar power, and hydropower. As the share of renewables in the energy mix grows, the grid is becoming increasingly sensitive to meteorological conditions, leading to periods of low renewable energy production—so-called “​renewable energy droughts.”

These energy security challenges must be addressed to ensure ​a consistent power supply and grid stability. India, with its large existing portfolio of renewable generation and good subseasonal predictability, serves as an ideal testbed for this analysis. In this article, we leverage a variety of data sources to quantify potential and realized renewable capacity in India from 1979 to 2022. Using this, we identify the timing and characteristics of historical renewable energy droughts and investigate the underlying weather patterns responsible.

Renewable Energy Variability

Renewable energy sources are inherently weather-dependent, causing production to vary on timescales from minutes to decades. This variability can lead to periods of critically low renewable energy generation, posing a challenge for energy system planners and grid operators.

Factors Influencing Renewable Energy Variability

The variability of renewable energy generation is influenced by several key factors:

  • Meteorological conditions: Wind speeds, solar irradiance, precipitation, and temperature all directly impact the output of wind, solar, and hydropower plants.
  • Seasonal patterns: Renewable energy resources exhibit strong seasonal cycles, with winter wind droughts and summer solar lulls occurring across many regions.
  • Geographic diversity: The spatial distribution of renewable generation assets can help mitigate local variations, leveraging complementarity between different resource types.

Quantifying Renewable Energy Variability

To quantify renewable energy variability, we utilize synthetic wind and solar photovoltaic production timeseries derived for the Indian energy grid using the ERA5 reanalysis dataset. These data span from 1979 to 2022 and cover the country’s significant installed capacity of 42 GW of wind power, 61 GW of solar power, and 51 GW of hydropower as of October 2022.

Temporal and Spatial Patterns of Renewable Energy Variability

Renewable energy droughts in India are most common from November to February, with the longest historical event lasting 9 days. These extended periods of critically low generation would put significant strain on the power system, both in terms of energy security and achieving decarbonization targets.

Interestingly, the majority (73%) of renewable energy drought days do not coincide with individual wind or solar energy droughts. This suggests that the droughts are driven by a combination of moderate wind and solar production, rather than extremely low generation from a single source. Recognizing this complementarity between resources is crucial for designing robust and reliable future energy systems.

Climatic Drivers of Renewable Energy Variability

To understand the weather patterns responsible for renewable energy droughts, we analyze the occurrence of India’s 30 established weather regimes during low-generation periods. These patterns, developed by Neal et al. (2022), capture the main monsoonal and non-monsoonal circulation types that influence the region’s climate.

Atmospheric Circulation Patterns

The weather regimes most associated with renewable energy droughts in India are the “winter dry period” (patterns 7 and 9), the “retreating monsoon” (pattern 1), and “western disturbances” (pattern 27). These patterns are characterized by low wind speeds, high cloud cover, and weak seasonal transitions—all of which can suppress both wind and solar power production.

Interestingly, the weather patterns driving extended multi-day droughts differ slightly from those causing single-day events. This suggests that moderately different meteorological conditions are responsible for the duration of these energy shortfalls.

Precipitation and Temperature Regimes

The weather patterns linked to renewable energy droughts are also associated with key regional climate features. For example, patterns 7, 9, and 27 occur primarily during the winter months, when precipitation is low and temperatures are cooler. Conversely, pattern 1 is more common during the retreating monsoon season, when cloud cover and precipitation can inhibit solar generation.

Extreme Weather Events

While not a dominant driver, extreme weather events such as heatwaves, cold snaps, and strong winds can also contribute to renewable energy droughts by temporarily overwhelming grid infrastructure or disrupting generation.

Seasonal Variations in Renewable Energy Supply

The seasonal variability of renewable energy resources is a crucial consideration for energy system planning and operation. Understanding these patterns can help identify complementary generation sources and guide investment in storage or other flexibility measures.

Seasonal Patterns in Solar Energy

Solar power generation in India peaks during the summer months, when clear skies and high temperatures maximize solar irradiance. Conversely, the winter dry period sees reduced solar production due to increased cloud cover and lower sun angles.

Seasonal Patterns in Wind Energy

Wind power in India exhibits a distinct seasonal cycle, with the strongest generation occurring during the summer monsoon season. This is driven by the strong westerly winds along the western coast of the peninsula. In the winter months, wind speeds often drop, leading to the renewable energy droughts discussed earlier.

Seasonal Patterns in Hydropower

Hydropower generation in India is closely tied to the monsoon cycle, with peak output during the wet summer months and reduced generation in the drier winter season. This seasonal pattern can help offset the variability of wind and solar, providing a valuable source of flexible, low-carbon energy.

Spatial Heterogeneity of Renewable Energy Resources

The uneven distribution of renewable energy resources across India presents both challenges and opportunities for the country’s energy transition.

Regional Differences in Renewable Energy Potential

While India has immense potential for both wind and solar power, the resources are not evenly distributed. The western states, such as Gujarat and Rajasthan, are particularly well-suited for solar development, while the southern regions offer the best wind resources.

Geographical Mismatches between Energy Demand and Supply

This spatial heterogeneity can create mismatches between the locations of peak renewable energy production and the areas of highest energy demand. Addressing these geographical imbalances will require robust transmission infrastructure and effective coordination between regional grids.

Interconnected Grid Systems and Energy Transmission

By integrating regional grid systems and enhancing long-distance energy transmission capabilities, India can better leverage the complementarity between its diverse renewable resources. This approach can help mitigate the impact of localized renewable energy droughts and ensure a more reliable, resilient, and sustainable power supply.

The European Future Energy Forum is a leading platform for discussing the continent’s transition to clean energy. By understanding the weather patterns responsible for renewable energy variability and complementarity, policymakers and industry stakeholders can develop more effective strategies to harness the full potential of wind, solar, and hydropower in India and beyond. For more information, visit www.europeanfutureenergyforum.com.

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