Diesel Fuel's Role In India's Air Pollution Crisis

India has been facing severe air pollution, which has emerged as one of the country's gravest social and environmental problems. The main sources of air pollution in India are biomass burning, coal burning for energy generation, industrial emissions, agricultural stubble burning, waste burning, construction activities, brick kilns, transport vehicles, and diesel generators. Diesel engines contribute significantly to deteriorating air quality, and India's growing economy is driving CO2 emissions, which increased by more than 55% in the last decade. In this context, it is essential to examine the role of diesel fuel in contributing to India's air pollution crisis.

Diesel engines and their emissions

Diesel engines, like other internal combustion engines, convert the chemical energy contained in diesel fuel into mechanical power. Diesel fuel is a mixture of hydrocarbons which, during an ideal combustion process, would produce carbon dioxide (CO2) and water vapour (H2O). However, in reality, the exhaust gases from diesel engines contain harmful emissions, including nitrogen compounds (NOx), carbon dioxide (CO2), carbon monoxide (CO), and particulate matter (PM).

The emissions from diesel engines are a major source of air pollution and have been linked to serious health issues, particularly in India, where air quality is a significant concern. Diesel engines contribute to the emission of ground-level ozone, which is formed when pollutants from transport vehicles, power plants, and factories react with sunlight. Ground-level ozone is harmful to human health and can cause respiratory problems, especially in children and the elderly. It also damages crops, trees, and other vegetation.

In addition to exhaust emissions, diesel engines also produce non-exhaust particle emissions, which consist of airborne particulate matter generated by the wearing down of brakes, clutches, tires, and road surfaces, as well as road dust. These non-exhaust particles can be significant, especially in older diesel engines or in electric vehicles, where regenerative braking reduces brake wear.

To address the issue of diesel emissions, stricter emission standards and regulations have been implemented by organizations like the US Environmental Protection Agency (EPA). These regulations have led to the development of Ultra-Low-Sulfur Diesel (ULSD) fuel, which helps reduce particulate emissions and nitrogen compound emissions. Additionally, the EPA has funded projects that aim to reduce diesel emissions from existing engines, and the Diesel Emissions Reduction Act Program provides grants and loans for initiatives that utilize diesel emission reduction technologies.

In India, some cities have shown improvements in air quality, with decreasing trends in PM10 and Sulphur dioxide levels. These improvements may be attributed to local measures to reduce Sulphur in diesel, the enforcement of clean fuel standards, and the increasing use of LPG and CNG as alternative fuels. However, diesel engines continue to contribute significantly to India's air pollution, and fine particle (PM2.5) related premature deaths are predicted to increase.

Fuel adulteration

India's air pollution is a complex issue with a multitude of contributing factors. One significant factor is the adulteration of fuel, which involves blending gasoline and diesel with lower-priced fuels such as kerosene, solvents, lubricants, and recycled lubricants. This practice is common in South Asia, including India, due to the differential tax structure, where gasoline is taxed more heavily than diesel, and diesel is taxed more than kerosene.

The financial incentives arising from these tax differences are the primary cause of fuel adulteration. As fuel prices rise, public transport drivers, particularly those on low wages, blend cheaper hydrocarbons into highly taxed ones to cut costs. This can result in significant monthly savings. For example, a 5% contamination of a 12,000-litre diesel tanker with kerosene can yield a profit of Rs 7,200 per tanker. Similarly, the adulteration of petrol with 15% low aromatic naphtha can earn Rs 25,000 per day.

The consequences of fuel adulteration are severe and contribute to India's air pollution crisis. Some adulterants increase emissions of harmful pollutants from vehicles, worsening urban air quality. For instance, kerosene, which is more challenging to burn than gasoline, results in higher levels of HC, CO, and PM emissions, even from catalyst-equipped cars. Additionally, kerosene has higher sulfur levels, contributing to sulfur dioxide emissions. The use of adulterated fuels also leads to damaged vehicles and increased emissions, undermining any small improvements in vehicle technology.

The problem is exacerbated by lax fuel quality standards, which allow for a broad permissible range for each quality parameter, making it easier for adulterated fuels to pass tests. The lack of stringent testing methods specifically designed to detect fuel adulteration further enables this practice. The government's aversion to implementing accurate adulteration tests and the weak penalties for adulteration contribute to the issue.

To address fuel adulteration, it is crucial to monitor fuel quality at the distribution point. Additionally, implementing more aggressive technology roadmaps to combat pollution and adulteration, as well as addressing the financial incentives driving the practice, are essential steps toward improving air quality in India.

Energy-related fuel combustion

The country's heavy reliance on traditional biomass for cooking and heating, such as fuel wood, agricultural waste, and biomass cakes, is a major factor. In 2019, around half of India's population depended primarily on biomass for their energy needs. When burned indoors with poor ventilation, biomass fuels expose households to harmful indoor air pollution, causing severe health issues. This has led to high levels of PM2.5 pollution and, to a lesser extent, NOx and SO2 emissions.

Additionally, the use of diesel engines in vehicles significantly contributes to deteriorating air quality. The transition from BS IV grade diesel to BSVI has the potential to reduce particle emissions in heavy-duty diesel vehicles. However, the choice of lubricating oil can also significantly impact emissions, and a combination of suitable fuel and lubricating oil is essential for reducing particle emissions.

The Indian government has implemented various measures to address these issues, such as introducing clean fuel standards, promoting the use of LPG and CNG as cleaner alternatives, and incentivizing the adoption of electric vehicles with tax waivers and cash incentives. These efforts are crucial as today's energy choices have direct and far-reaching implications for India's growing population.

Transport vehicles

India's air pollution has emerged as one of the country's most pressing social and environmental issues. Transport vehicles are a significant contributor to this crisis, with emissions from cars, motorbikes, scooters, and heavy-duty diesel vehicles playing a key role.

In cities like Bangalore, around 50% of children suffer from asthma, and India's air pollution has been linked to approximately 1.2 million premature deaths in 2019 alone. The country's growing economy is driving up CO2 emissions, which increased by over 55% in the last decade and are expected to rise further by 2040.

One of the main issues with transport in India is the slow average trip speed due to congested roads. Vehicles emit air pollutants 4 to 8 times more when stuck in traffic congestion, and they consume a lot more fuel per trip. The growth in the number of vehicles and mileage in India is outpacing efforts to curb emissions.

To tackle this issue, India's capital, New Delhi, has implemented a series of measures. These include limiting the number of fossil fuel cars each household can purchase, providing incentives for electric bikes and scooters, and imposing a levy on petrol sales. The city aims for a 30% electric vehicle (EV) penetration by 2030 and plans to waive some local taxes on the purchase of hybrids and electric vehicles.

Additionally, India has introduced clean fuel standards and is encouraging the use of LPG as domestic fuel instead of coal or fuelwood. Studies have also been conducted to explore ways to reduce particle emissions from diesel vehicles, such as using different fuel blends and lubricating oils.

However, despite meeting Euro III and Euro IV emissions standards, concerns remain about the toxic emissions from diesel engines. The transition to cleaner alternatives, such as electric vehicles, is crucial to improving air quality and reducing the devastating health impacts of pollution in India.

Air pollution control technologies

Diesel fuel is a significant contributor to India's air pollution problem. The country's air quality has been described as "hazardous", with New Delhi ranked as the world's most polluted city.

To combat this issue, India has implemented a range of air pollution control technologies, focusing on reducing emissions from vehicles and improving fuel quality.

Vehicle Emissions

Technological advances have been made to reduce particle emissions from vehicles, with a particular focus on heavy-duty diesel vehicles. For instance, the transition from BS IV grade diesel to BSVI has the potential to reduce particle emissions from these vehicles. The choice of lubricating oil can also significantly impact emissions, with certain combinations of fuel and lubricating oil being optimal for reducing emissions.

Fuel Quality

India has gradually tightened its fuel quality standards since the mid-1990s, adopting the European template for vehicle emissions and fuel quality standards, known as Bharat Stages (BS). The reduction of sulfur content in diesel fuel is a key focus, as it inhibits the functioning of after-treatment systems and corrodes engines and pipes. The BS VI regulation, in particular, enabled the introduction of advanced emission control technologies, including:

• Diesel particulate filters (DPF)
• Selective catalytic reduction (SCR) systems

Other Initiatives

In addition to technological advances, the Indian government has implemented various initiatives to combat air pollution:

• The Great Green Wall of Aravalli: A 1,600-kilometre-long and 5-kilometre-wide ecological corridor aimed at combating pollution by planting native trees.
• Aerosol and Air Quality Research Facility: A research facility launched in partnership with IIT Bombay and the McKelvey School of Engineering of Washington University in St. Louis to study air pollution in India.
• Odd-Even Rule: A rationing method implemented in Delhi in 2017, where cars with number plates ending in odd digits could only be driven on certain days, while even-numbered plates could be driven on the remaining days.

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