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Papers by Anasuya Gangopadhyay

<p>In a steadily decarbonizing electricity system, it becomes increasingly importan... more <p>In a steadily decarbonizing electricity system, it becomes increasingly important to explore cost-effective wind-solar-storage combinations to replace conventional fossil-fuelled power generation without compromising grid reliability. For a renewable-rich state in Southern India (Karnataka), we systematically assess the economics of various wind-solar-battery energy mixes given decreasing fossil-fuelled base generation and hydropower availability using Pareto frontiers. Our approach considers hourly load data, simulates generation based on hourly weather reanalysis products, and models the effects of battery charging and discharging on battery lifetime. We find that the allowed curtailment level limits the achievable grid reliability. Given declining baseload generation and available hydropower in the state electricity grid, the wind-solar-battery combined system can provide limited reliability, which declines as the grid is progressively decarbonized. A fully decarbonized grid with 2 GW of hydropower and a stringent 10% curtailment threshold can achieve maximum reliability of 66%. These values are sensitive to available hydropower capacity, baseload generation from fossil fuel, and the curtailment threshold. For a fully decarbonized grid, increasing the allowed curtailment threshold of renewable generation (during times of excess) to 80% would ensure 99% grid reliability. However, such a solution would be costly, requiring large wind-solar installations that exceed officially assessed potential, constrained by land allocation. Furthermore, these calculations show that adding storage capacity without concomitant expansion of renewable generation capacity is inefficient. The findings highlight the importance of a fresh examination of curtailment thresholds, renewable potential, and possibilities of demand-side management to evaluate pathways to the decarbonization of the electricity grid while maintaining reliability.</p>

Current Science, 2016

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000-8700 MW (11 BU) of wind and 3300-3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

Current Science, 2016

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000-8700 MW (11 BU) of wind and 3300-3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

<p>Smoothing of wind generation variability is important for grid integration of la... more <p>Smoothing of wind generation variability is important for grid integration of large-scale wind power plants. One approach to achieving smoothing is aggregating wind generation from plants that have uncorrelated or negatively correlated wind speed. It is well known that the wind speed correlation on average decays with increasing distance between plants, but the correlations may not be explained by distance alone. In India, the wind speed diurnal cycle plays a significant role in explaining the hourly correlation of wind speed between location pairs. This creates an opportunity of “diurnal smoothing”. At a given separation distance the hourly wind speeds correlation is reduced for those pairs that have a difference of +/- 12 hours in local time of wind maximum. This effect is more prominent for location pairs separated by 200 km or more and where the amplitude of the diurnal cycle is more than about  0.5 m/s. “Diurnal smoothing” also has a positive impact on the aggregate wind predictability and forecast error. “Diurnal smoothing” could also be important for other regions with diurnal wind speed cycles.</p>

Current Science, 2017

An international workshop on the performance and potential of wind energy systems in India was he... more An international workshop on the performance and potential of wind energy systems in India was held in Bengaluru recently. It included participants from industry, research organizations, academic institutes and decision-makers from India and the USA. The two-day workshop began with a welcome address by S. K. Satheesh (Chairman, Divecha Centre for Climate Change, IISc, Bengaluru) who highlighted the need for examining the performance of existing power plants and address the challenges to meet the ambitious target of 60 GW of installed wind power capacity by 2022.

The installed capacity of wind power plants in India is expected to reach 60 Gigawatts by 2022. T... more The installed capacity of wind power plants in India is expected to reach 60 Gigawatts by 2022. The increasing share of electric power generation from wind will pose new challenges for grid stability as wind power is intermittent by nature. Three major types of variations in wind generation are, seasonal, diurnal and minute to minute. This paper investigates the possibility of smoothing of diurnal variation of wind generation through physical dispersion of wind power plants across the state. Wind power plants are located across Karnataka in the form of clusters. Our study shows that two plants located within 10km radius show a correlation of more than 80% in power generation while, the wind plants located further away show a correlation that is around 40% or less. Two groups of plants having similar total generation located in two different regions with different diurnal variation can contribute to geographical smoothing. Keywords-wind energy; geographycal smoothing; Karnataka wind ...

Power grid is a common platform connecting all the generating stations and demand centres (loads)... more Power grid is a common platform connecting all the generating stations and demand centres (loads), where the energy is generated and consumed instantaneously. The demand varies from minute to minute, and the generation needs to be adjusted accordingly to meet the demand. However, with large intermittent renewable power plants coming online, this balancing becomes even more complicated. Although there is a growing emphasis on predicting the renewable generation, prediction of demand also can help in grid-level energy management. In this paper, we compare the prevalent demand forecasting practice with the model developed using multivariable regression technique. This simple model shows an improvement of 3% over the present demand prediction scenario, with respect to the mean absolute error. In future, use of more precise data for model training and addition of further variables may increase the accuracy level. This model does not need any large computational set-up or capacity buildin...

Current Science

Smeets, P. A., The first taste is always with the eyes: a metaanalysis on the neural correlates o... more Smeets, P. A., The first taste is always with the eyes: a metaanalysis on the neural correlates of processing visual food cues.

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000–8700 MW (11 BU) of wind and 3300–3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

NIAS Special Publication: NIAS report-SP8-2017; ISBN 978-93-83566-25-9, 2017

Karnataka is the most power deficit state in the Southern regional grid. The average and peak def... more Karnataka is the most power deficit state in the Southern regional grid. The average and peak deficit has been higher than the national average for the last five years. Chronic power deficits resultin load shedding leading to not only inconveniences, but also economic losses. One of the solutions to address power deficits is to utilize vacant rooftops and install solar panels. Institutions like schools, colleges, universities, and offices are suited specifically for this purpose as these have their major electricity requirement during the day when the sun is available (8am to 6pm). Rooftop solar power can meet a substantial portion of institutional electricity demand on working days; also it can be exported to the grid during weekends and holidays, when the institutes’ activities are minimal. This report gives the experience of NIAS with its 100kWp solar rooftop. Commissioned in October 2014, the electricity generated from the plant accounts for 60-65% of NIAS’s monthly electricity consumption showing a payback period of eight years.

<p>In a steadily decarbonizing electricity system, it becomes increasingly importan... more <p>In a steadily decarbonizing electricity system, it becomes increasingly important to explore cost-effective wind-solar-storage combinations to replace conventional fossil-fuelled power generation without compromising grid reliability. For a renewable-rich state in Southern India (Karnataka), we systematically assess the economics of various wind-solar-battery energy mixes given decreasing fossil-fuelled base generation and hydropower availability using Pareto frontiers. Our approach considers hourly load data, simulates generation based on hourly weather reanalysis products, and models the effects of battery charging and discharging on battery lifetime. We find that the allowed curtailment level limits the achievable grid reliability. Given declining baseload generation and available hydropower in the state electricity grid, the wind-solar-battery combined system can provide limited reliability, which declines as the grid is progressively decarbonized. A fully decarbonized grid with 2 GW of hydropower and a stringent 10% curtailment threshold can achieve maximum reliability of 66%. These values are sensitive to available hydropower capacity, baseload generation from fossil fuel, and the curtailment threshold. For a fully decarbonized grid, increasing the allowed curtailment threshold of renewable generation (during times of excess) to 80% would ensure 99% grid reliability. However, such a solution would be costly, requiring large wind-solar installations that exceed officially assessed potential, constrained by land allocation. Furthermore, these calculations show that adding storage capacity without concomitant expansion of renewable generation capacity is inefficient. The findings highlight the importance of a fresh examination of curtailment thresholds, renewable potential, and possibilities of demand-side management to evaluate pathways to the decarbonization of the electricity grid while maintaining reliability.</p>

Current Science, 2016

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000-8700 MW (11 BU) of wind and 3300-3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

Current Science, 2016

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000-8700 MW (11 BU) of wind and 3300-3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

<p>Smoothing of wind generation variability is important for grid integration of la... more <p>Smoothing of wind generation variability is important for grid integration of large-scale wind power plants. One approach to achieving smoothing is aggregating wind generation from plants that have uncorrelated or negatively correlated wind speed. It is well known that the wind speed correlation on average decays with increasing distance between plants, but the correlations may not be explained by distance alone. In India, the wind speed diurnal cycle plays a significant role in explaining the hourly correlation of wind speed between location pairs. This creates an opportunity of “diurnal smoothing”. At a given separation distance the hourly wind speeds correlation is reduced for those pairs that have a difference of +/- 12 hours in local time of wind maximum. This effect is more prominent for location pairs separated by 200 km or more and where the amplitude of the diurnal cycle is more than about  0.5 m/s. “Diurnal smoothing” also has a positive impact on the aggregate wind predictability and forecast error. “Diurnal smoothing” could also be important for other regions with diurnal wind speed cycles.</p>

Current Science, 2017

An international workshop on the performance and potential of wind energy systems in India was he... more An international workshop on the performance and potential of wind energy systems in India was held in Bengaluru recently. It included participants from industry, research organizations, academic institutes and decision-makers from India and the USA. The two-day workshop began with a welcome address by S. K. Satheesh (Chairman, Divecha Centre for Climate Change, IISc, Bengaluru) who highlighted the need for examining the performance of existing power plants and address the challenges to meet the ambitious target of 60 GW of installed wind power capacity by 2022.

The installed capacity of wind power plants in India is expected to reach 60 Gigawatts by 2022. T... more The installed capacity of wind power plants in India is expected to reach 60 Gigawatts by 2022. The increasing share of electric power generation from wind will pose new challenges for grid stability as wind power is intermittent by nature. Three major types of variations in wind generation are, seasonal, diurnal and minute to minute. This paper investigates the possibility of smoothing of diurnal variation of wind generation through physical dispersion of wind power plants across the state. Wind power plants are located across Karnataka in the form of clusters. Our study shows that two plants located within 10km radius show a correlation of more than 80% in power generation while, the wind plants located further away show a correlation that is around 40% or less. Two groups of plants having similar total generation located in two different regions with different diurnal variation can contribute to geographical smoothing. Keywords-wind energy; geographycal smoothing; Karnataka wind ...

Power grid is a common platform connecting all the generating stations and demand centres (loads)... more Power grid is a common platform connecting all the generating stations and demand centres (loads), where the energy is generated and consumed instantaneously. The demand varies from minute to minute, and the generation needs to be adjusted accordingly to meet the demand. However, with large intermittent renewable power plants coming online, this balancing becomes even more complicated. Although there is a growing emphasis on predicting the renewable generation, prediction of demand also can help in grid-level energy management. In this paper, we compare the prevalent demand forecasting practice with the model developed using multivariable regression technique. This simple model shows an improvement of 3% over the present demand prediction scenario, with respect to the mean absolute error. In future, use of more precise data for model training and addition of further variables may increase the accuracy level. This model does not need any large computational set-up or capacity buildin...

Current Science

Smeets, P. A., The first taste is always with the eyes: a metaanalysis on the neural correlates o... more Smeets, P. A., The first taste is always with the eyes: a metaanalysis on the neural correlates of processing visual food cues.

Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected ... more Karnataka suffers from chronic electricity shortages and daily load-shedding, which are expected to persist despite planned additions of conventional power. Using four illustrative scenarios based on different assumptions, we estimate the additional contributions wind and solar power sources could make to reduce these deficits by FY2022. The method developed estimates expected hourly deficits in FY2022 from projected unrestricted demands and expected availability from conventional sources. We estimate that additional 8000–8700 MW (11 BU) of wind and 3300–3500 MW (5 BU) of solar power would reduce the annual deficit by approximately three-fourths. A recommended pumped hydro storage facility will reduce the deficits further by 10% and help in meeting the daily peaks in demand.

NIAS Special Publication: NIAS report-SP8-2017; ISBN 978-93-83566-25-9, 2017

Karnataka is the most power deficit state in the Southern regional grid. The average and peak def... more Karnataka is the most power deficit state in the Southern regional grid. The average and peak deficit has been higher than the national average for the last five years. Chronic power deficits resultin load shedding leading to not only inconveniences, but also economic losses. One of the solutions to address power deficits is to utilize vacant rooftops and install solar panels. Institutions like schools, colleges, universities, and offices are suited specifically for this purpose as these have their major electricity requirement during the day when the sun is available (8am to 6pm). Rooftop solar power can meet a substantial portion of institutional electricity demand on working days; also it can be exported to the grid during weekends and holidays, when the institutes’ activities are minimal. This report gives the experience of NIAS with its 100kWp solar rooftop. Commissioned in October 2014, the electricity generated from the plant accounts for 60-65% of NIAS’s monthly electricity consumption showing a payback period of eight years.