Figure 2.6: Total CO quantity attributable to traffic, broken down by emission source and vehicle category.
The study's main findings revealed that deteriorated road pavements cause vehicles to slow down and emit more pollutants. The most carbon monoxide (CO) pollution (72.18 percent) appeared to be caused by passenger cars, while vehicle engines produced the most carbon dioxide (CO2) (47.43 percent ). However, 93.58 percent of pollutant emissions occurred when the engine was hot, depending on how a vehicle was driven and the type of fuel utilized. Alternative fuels and avoiding obsolete vehicles were recommended to reduce CO2 emissions; overheated engines released the greatest nitrogen oxides (98.09%), with heavy vehicles producing 41.7 percent compared to passenger cars' 18.9%.
Kamruzzaman, Mohammad Haider, and Takeshi Mizunoya (2019) conducted a study in Bangladesh using COPERT IV to determine the best corrective fuel tax for road cars. This study compares climate change measures to Bangladesh's optimum remedial fuel tariffs. The authors calculated the externalities using the COPERT IV European road transport emission model. They then used the same methodology to calculate the reduction in greenhouse gas emissions caused by the gasoline tax. Finally, they found a relationship between the gasoline tax rate and the emissions removal. The goal of this study was to see if the current fuel tax could be combined with a $1.20 per gallon diesel tax to meet the country's greenhouse gas reduction goal. Fuel charges could be used to encourage lawmakers to pass climate-change legislation.
Bangladesh's vehicle fleet as compared to the COPERT vehicle category in this study, and the two were combined.
Table 2.2: Reclassification of vehicle classes based on COPERT Class
Vehicles were classified by size and weight, as shown in Table 2.2. Small trucks weighed less than 7.5 tonnes, whereas huge trucks weighed more than 14. Large buses, on the other hand, weighed more than 18 tonnes, while microbuses weighed less than 15 tonnes.
According to the study's findings, total PM2.5 emissions from the road transport sector totaled 13,527.09 tons, with urban roads accounting for 39.75 percent, rural roads 36.18 percent, and highways 24.07 percent.
Figure 2.7 shows the percentage of total emissions attributed to fuel in BAU (calculation from COPERT IV)
Diesel cars are the primary source of PM2.5 (Fig. 2.5), accounting for 86 percent of total pollution and only 14 percent from gasoline vehicles. Minibusses, oversized vehicles, and large buses are responsible for 22.51 percent, 18.8 percent, and 16.66 percent of total emissions. Other cars provide less than 10%, whereas Jeeps contribute 11%. Motorcycles are responsible for 93% of all gasoline-powered vehicle emissions. Heavy-duty trucks, motorcycles, passenger cars, and light commercial vehicles, on the other hand, emit 26.96 percent, 12.61 percent, 7.86 percent, and 2.42 percent of total emissions, respectively.
2.7 Other Emission Inventory for Estimating Vehicular Emissions:
In addition to COPERT, other emission inventory models are used to estimate on-road traffic emissions worldwide. Although maximum inventory models are based on European or American criteria, they might be effective in Asian countries. For regional emission estimation, many Asian countries utilize these models. The prominent emission inventory models are the International Vehicle Emissions (IVE) Model, EMIT, The Comprehensive Modal Emissions Model (CMEM), Motor Vehicle Emission Simulator (MOVES), and MOBILE.
2.7.1 Modal Emissions in a Comprehensive Way (CMEM)
Researchers at UC Riverside created the Comprehensive Modal Emissions Model (CMEM). LDV and LDT emissions are calculated using CMEM. The term "comprehensive" refers to a model's ability to predict emissions for various LDVs and LDTs under different operating situations. Over 300 cars were monitored second-by-second across three driving cycles, including the Federal Test Procedure (FTP), US06, and the Modal Emission Cycle, including both engine-out and tailpipe emissions of 30 high-9 polluters (MEC). For various vehicle/technology categories, CMEM calculates second-by-second tailpipe emissions and fuel consumption. The model is based on a physical method that breaks down the entire emission process into its constituent parts. Model inputs include vehicle and operation variables such as speed, acceleration, and road grade, as well as model-calibrated factors such as cold-start coefficients and engine friction factors (Barth et al. 2000).
Model: 2.7.2 MOBILE6
The MOBILE5a and MOBILE6 models were developed with the help of the EPA's Transportation and Air Quality Department (OTA). Because the MOBILE6 is the most recent model in the MOBILE family, it will be covered in greater detail. In terms of design, the MOBILE6 is far from the MOBLE5a. MOBILE6 was developed using data from current vehicle-emission testing conducted by the EPA, CARB, and automakers and inspection and maintenance tests undertaken in several states. MOBILE6 uses various route types, including highways, airways, and others, to estimate emission factors. Emission factors may be adjusted to account for different facility types and average speeds based on vehicle testing conducted across several facility cycles. MOBILE6 also estimates emission factors for the beginning and end of the route separately.
2.7.3 The IVE Model (International Vehicle Emissions)
The International Vehicle Emissions Model (IVE) is a software tool designed to calculate automobile emissions. Most impoverished countries have little awareness of automotive emissions, and the ability to calculate accurate emissions estimates is critical for air quality control planning. Few countries, such as the United States and Europe, have developed relatively precise methods for predicting emissions, yet these models are specifically designed for that country's specific locations. The models employed in the United States and Europe cannot account for the differences in technology and circumstances that exist in most emerging countries. The bulk of current models fails to account for the whole range of global warming and local hazardous emissions, which are necessary for a thorough assessment of the impact of automobiles. The International Vehicle Emissions (IVE) Model was created to provide developing countries the flexibility they need to successfully tackle mobile source air emissions.
Simulator for Motor Vehicle Emissions (Motor Vehicle Emission Simulator, version 2.7.4) (MOVES)
The MOtor Vehicle Emission
Simulator, or MOVES, is a cutting-edge emissions modeling system developed by
the Environmental Protection Agency (EPA) that estimates air pollutants such as
criteria pollutants, greenhouse gases, and air toxics emitted by motor
vehicles. Bulldozers and lawnmowers are included in the MOVES program, as are
on-road and off-road vehicles and equipment. Buses, trucks, and passenger
automobiles are all examples of on-road vehicles. MOVES does not apply to
commercial airplanes, trains, or ships. MOVES considers federal emissions
requirements, vehicle and equipment activity, fuels, temperatures, humidity,
and emission-control measures, including inspection and maintenance (I/M)
programs. MOVES is a bottom-up emissions model designed to estimate emissions
from various physical emission processes based on the source. MOVES calculates
the "fleet average" emissions rather than modeling the emissions from
individual cars or pieces of equipment. MOVES also adjust emission rates to
meet real-world conditions.