Diesel has been a popular choice of fuel for commercial fleet vehicles for decades due to its high-energy content and efficiency. However, in recent years, the need for reducing GHG emissions has led to a reassessment of diesel's suitability and sparked the development of cleaner diesel technologies. This research evaluates the latest advancements and their implications for the use of diesel fuel in commercial vehicles.

New Advancements in Diesel Technology

Several technological advancements have recently been made in the diesel industry to curb emissions and improve fuel efficiency. These include innovations such as Selective Catalytic Reduction (SCR) systems, Diesel Particulate Filters (DPF), Exhaust Gas Recirculation (EGR), and biodiesel fuels.

• Selective Catalytic Reduction (SCR): SCR is an advanced active emissions control technology system that injects a liquid-reductant agent through a special catalyst into the exhaust stream of a diesel engine. This process converts nitrogen oxides, one of the major air pollutants, into nitrogen, water, and a tiny amount of carbon dioxide, significantly reducing the emissions profile of diesel engines.
• Diesel Particulate Filters (DPF): DPFs remove the particulate matter or soot from the exhaust gas of a diesel engine, thus minimizing the emission of harmful pollutants. Recent enhancements to DPF technologies have increased their effectiveness and longevity.
• Exhaust Gas Recirculation (EGR): EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This can lower temperatures in the combustion chamber, resulting in reduced nitrogen oxide emissions.
• Biodiesel: Biodiesel is a renewable, biodegradable fuel manufactured domestically from vegetable oils, animal fats, or recycled restaurant grease. It is a cleaner-burning replacement for petroleum diesel and can be used in diesel engines with little or no modifications.

Quantifying GHG Emissions in GGE

Estimating the GHG emissions of diesel fuel involves comparing it with gasoline in terms of GGE. For the comparison, it's important to note that diesel fuel contains approximately 11% more energy than gasoline per gallon, thus, a gallon of diesel fuel has more carbon and will emit more CO2 when burned than a gallon of gasoline (EPA, 2021).

For this study, we use the Energy Information Administration’s (EIA) measurements, where 1 GGE = 125,000 BTU. Given that diesel has about 138,690 BTU/gallon, one gallon of diesel is equivalent to 1.11 GGE. Therefore, to calculate the emissions, we need to account for the higher energy content of diesel, making the diesel to GGE comparison more accurate.

Diesel’s Effect on Sustainability

• Economic Sustainability: With the advent of cleaner diesel technologies, diesel can continue to be a cost-effective choice for commercial fleets, particularly for heavy-duty vehicles. New diesel technologies have also improved fuel economy, reducing operating costs over the vehicle's life.
• Environmental Sustainability: Cleaner diesel technologies have significantly reduced diesel's environmental impact, but it still contributes to GHG emissions. Biodiesel, particularly, is a more sustainable alternative, given its lower emissions and renewability.
• Social Sustainability: Reduced emissions from cleaner diesel technologies can improve air quality, resulting in health benefits. However, diesel vehicles are typically noisier than their electric counterparts, which can impact noise pollution levels.

Economic, Environmental, and Social Cost

The total cost of using diesel in commercial vehicles goes beyond the purchase price of the fuel. It includes environmental costs such as climate change effects due to GHG emissions, health costs due to air pollution, and social costs such as noise pollution. These "external costs" are difficult to quantify precisely, but studies suggest that they can be substantial, warranting the need for more sustainable transport solutions.

Forecast of the Growth Rate of Diesel as Commercial Vehicle Fuel

Despite the progress in cleaner diesel technologies, the commercial vehicle sector is experiencing a transition towards electric and hydrogen fuel cell technologies. This shift is driven by increasing regulatory pressure to reduce emissions, the falling cost of batteries, and a growing public interest in sustainability.

In this environment, the growth rate of diesel as a commercial vehicle fuel is expected to decrease. Nevertheless, given the existing infrastructure and the current lack of feasible alternatives for long-haul and heavy-duty vehicles, diesel will likely remain a significant part of the commercial vehicle fuel mix in the near to medium term.

Conclusion

Advancements in diesel technology have reduced its environmental impact and improved its cost-effectiveness, sustaining its use in the commercial fleet vehicle sector. However, with the shift towards zero-emission vehicles, the role of diesel is expected to diminish over time. As technology and infrastructure for alternative fuels continue to develop, a more sustainable transportation future seems attainable.

Despite the forecasted decrease in the growth rate of diesel as a commercial vehicle fuel, the transition towards more sustainable alternatives will need to be strategically managed to ensure energy security, economic stability, and social acceptance. The pace of this transition will be influenced by a combination of factors, including government policy, market forces, technological advances, and societal preferences. These variables should be continuously monitored to ensure an accurate understanding of the ongoing evolution in the commercial vehicle sector.