Impact of Air Pollution from Coal-Fired Electricity Generation on Crop Productivity in India

Academic Background

India is one of the world’s largest agricultural producers and also one of the most air-polluted countries. Coal-fired power generation is a primary source of electricity supply in India, but the air pollutants it generates, especially nitrogen dioxide (NO₂), have a significant impact on crop productivity. While the effects of air pollution on human health have been widely studied, its quantitative impact on crop productivity has not been fully assessed. This paper aims to quantify the impact of NO₂ emissions from coal-fired power plants on rice and wheat productivity in India, exploring how this pollution affects food security and economic development.

India’s food security is closely linked to its power supply. With increasing population and economic development, India needs to balance increasing food production with expanding electricity supply. However, air pollution from coal-fired power generation may negatively affect crop yields, thereby weakening India’s food production capacity. Therefore, this study is not only significant for India but also has far-reaching implications for global food security.

Paper Source

This study was conducted by Kirat Singh, David B. Lobell, and Inês M. L. Azevedo, researchers from Stanford University’s Emmett Interdisciplinary Program in Environment and Resources. The paper was published in the Proceedings of the National Academy of Sciences (PNAS) on February 3, 2025.

Research Process

1. Data Collection and Integration

The research team integrated data from multiple sources, including: - Satellite Observations: Daily NO₂ tropospheric vertical column density (TVCD) data from the TROPOMI sensor. - Electricity Generation Data: Daily generation time series from India’s Central Electricity Authority. - Vegetation Data: Daily near-infrared reflectance (NIRv) data derived from MODIS sensors to assess crop growth conditions. - Meteorological Data: Wind direction, temperature, and precipitation data from the ERA5-Land reanalysis dataset. - Cropland Data: Cropland coverage data from the ESA WorldCover dataset.

These data were integrated into a unified framework with a spatial resolution of 1 km and a temporal span from 2018 to 2022.

2. Regression Model Construction

The research team developed a regression model to estimate the contribution of coal-fired power generation to NO₂ concentrations. Key steps in the model included: - Wind Direction Classification: Dividing wind directions into eight categories (north, northeast, east, southeast, etc.) and calculating generation volumes for each direction. - Distance Classification: Categorizing the impact range of power plants on cropland into ten distance categories (0-10 km, 10-20 km, …, 90-100 km). - Fixed Effects Control: Using point fixed effects and season-state fixed effects to control for time-invariant factors.

3. Association Between NO₂ Concentrations and Crop Productivity

Using previously published coefficients relating NO₂ concentrations to crop productivity, the team applied these coefficients to the estimated NO₂ concentration changes to quantify the impact of coal-fired power generation on crop yields. Specific steps included: - NO₂ Concentration Change Estimation: Based on the regression model, estimating the NO₂ concentration changes caused by coal-fired power generation at each cropland point. - Crop Productivity Loss Estimation: Utilizing the relationship between NO₂ concentration changes and NIRv to estimate potential yield losses.

4. Data Analysis and Results

The research team quantified uncertainty using bootstrap methods, calculating 95% prediction intervals. Main results from the data analysis include: - NO₂ Concentration Changes: Significant impacts of coal-fired power generation on NO₂ concentrations up to 100 km away, especially in downwind croplands. - Crop Yield Losses: Annual yield losses exceeding 10% in some regions, equivalent to approximately six years of average annual yield growth in India between 2011 and 2020. - Economic Losses: Converting yield losses into economic losses, the study estimated that coal-fired power generation resulted in annual economic losses reaching hundreds of millions of dollars.

Key Findings

1. NO₂ Concentration Changes

The study found that coal-fired power generation significantly impacted NO₂ concentrations within a 100 km radius. Downwind croplands were most affected, particularly within 30 km. This effect was especially pronounced during winter (the wheat-growing season).

2. Crop Yield Losses

The study estimated that in certain areas, rice and wheat yields lost more than 10% annually. For instance, in West Bengal, Madhya Pradesh, and Uttar Pradesh, NO₂ emissions from coal-fired power plants led to significant crop yield losses. These losses pose a serious threat to India’s food security.

3. Economic Losses

By converting yield losses into economic terms, the study estimated that coal-fired power generation resulted in annual economic losses of several hundred million dollars. In 2019, the economic losses for rice and wheat were $420 million and $400 million, respectively.

4. Comparison of Health and Crop Losses

The study also compared the impacts of coal-fired power generation on health and crop losses. Although the total monetary value of crop losses was lower than health-related losses, the intensity of crop loss per unit of electricity generated exceeded that of health losses. At some power plants, the intensity of crop losses even surpassed health losses.

Conclusion

This study is the first to quantify the impact of NO₂ emissions from coal-fired power generation on rice and wheat productivity in India. It shows that coal-fired power generation not only poses a threat to human health but also significantly affects India’s food security. The findings provide scientific evidence for Indian policymakers to formulate emission reduction policies, emphasizing the importance of considering agricultural impacts when reducing coal-fired power generation.

Research Highlights

1. Quantitative Assessment: The study provides the first quantitative assessment of the specific impact of coal-fired power generation on crop yields, filling a gap in the literature.
2. Multi-source Data Integration: By integrating satellite observations, electricity generation data, meteorological data, and cropland data, the study demonstrates the powerful application of multi-source data in environmental research.
3. Policy Guidance: The results offer important guidance for energy and agricultural policy-making in India and other developing countries.

Additional Value

The study also suggests directions for future research, including: - Impact of Non-coal Emission Sources: Future studies could further evaluate the impact of other NO₂ emission sources (such as transportation and industry) on crop yields. - Season-specific Reduction Strategies: The study indicates that reduction strategies targeting crop growing seasons might yield greater social benefits.

This research not only provides scientific evidence for India but also offers valuable insights for other countries facing similar challenges globally.