India’s potent black carbon emissions from kerosene lamps make up 10% of total residential emissions: Study
India’s reliance on kerosene-based lamps as a secondary lighting source leads to release of 12.5 gigagrammes (Gg) per year of a potent climate pollutant called black carbon. This accounts for about 10 per cent of the total residential black carbon emissions, which includes cooking, heating and lighting, according to a new study.
Roughly 30 per cent of rural households rely on kerosene lighting during power cuts as a secondary light source, with the figure reaching as high as 70 per cent in the eastern regions.
The study, published in the journal Atmospheric Pollution Research, found that eastern India contributed 7.5 Gg or 60 per cent of India’s black carbon emissions from secondary light sources.
Though India has made strides in reducing residential kerosene consumption by extending electric grids under the Saubhagya scheme, more work needs to be done.
“Due to frequent power outages caused by the imbalance between electricity demand and supply, people are forced to use non-clean lighting sources like kerosene lighting as secondary light source,” study author Navinya Chimurkar from the Indian Institute of Technology (IIT), Bombay told Down To Earth.
Navinya and colleagues from IIT Bombay focused on emissions from kerosene lighting in the residential sector, especially from rural regions.
From 2018-2020, the team travelled to 6,000 households in India to survey usage patterns. “We looked at the different types of fuels, and different devices people use for heating and lighting,” Chimurkar explained.
The team noted two common types of kerosene lighting devices used in Indian households. One is the wick lamp, which is simple and homemade, and the other is the hurricane lamp, the more sophisticated version. The survey also helped them calculate fuel consumption.
Next, they looked at black carbon emissions, a potent short-lived climate pollutant. The 20-year global warming potential of black carbon is estimated to be around 700–4,000. They have a short atmospheric lifetime of less than a week.
But to do this, they first had to estimate black carbon emission factors, which is the amount of pollutant released in grams per kg of the fuel (kerosene) burnt, from different lighting devices. They also calculated the burn rate, which is proportional to the amount of fuel consumed. “If the burn rate is low, less fuel is burned,” Chimurkar added.
Burn rates for flat wick lamps, hurricane and wick lamps were estimated to be 14.7, 15.3 and 5.4 grams per hour, respectively.
The emissions factor for black carbon was 190 g per kg of kerosene burnt in flat wick lamps, followed by 61.4 g per kg for wick lamps and hurricane lamps with 17.2 g per kg.
Though kerosene has a lower burn rate than biomass, the emissions factors of the former are higher than the latter. For example, emissions factors for black carbon for Kerosene lights vary between 17 g and 190 g per kg, surpass biomass’s 1-2g per kg, Chimurkar added.
To calculate black carbon emissions, they considered fuel consumption, burn rate and emission factors. Their estimate was 12.5 Gg per year for 2017. Bihar alone emitted more than 3 Gg per year, the study highlighted.
The team also estimated emissions from Diwali lights, which are typically powered by sesame oil or some edible oil. This was compared with paraffin wax candles, also used during the festival.
The top states with the highest black carbon emissions from sesame oil lamps during Diwali include Uttar Pradesh at 431 megagrammes (Mg), Maharashtra at 306 Mg, Andhra Pradesh at 291 Mg, Tamil Nadu at 260 Mg and Bihar at 264 Mg.
The oil lamps could emit an additional 3 Gg of black carbon in two days. This value is 40 times greater than the daily black carbon emissions from residential kerosene lighting, the study highlighted.
Replacing it with wax-based lamps could potentially reduce emissions by roughly 90 per cent, the authors noted.
“Now, we know the regions where these activities are prevalent. We need to improve the electricity supply to reduce people’s usage of kerosene-based lamps,” Navinya explained.
He also added that bringing more awareness on alternate lighting sources like solar lamps and rechargeable lamps could help.