Assessing and Managing the Direct and Indirect Emissions from Electric and Fossil-Powered Vehicles

Abstract

Efforts to improve air quality and concerns about global warming make transportation mediums that do not produce emissions more attractive to end users. Meanwhile, some of these transportation mediums are powered by an electricity grid that generates a great deal of emissions. This study compared the greenhouse gas GHG emissions for both electric and fossil-powered vehicles using estimates of tailpipe emissions of fossil-powered vehicles and the indirect emissions from the electricity grid. Furthermore, a system dynamic model was developed for a more holistic review of the GHG emissions for both electric and fossil-powered vehicles. The result indicated that in terms of associated emissions from the grid, electric-powered vehicles are not always better than fossil-powered vehicles when the electricity is not from a renewable source. The GHG emissions for electric-powered vehicles are dependent on both the electricity usage rate of the vehicle and the GHG emissions that are associated with the production of that amount of electricity. Further opportunities exist in renewable and clean energy technologies for various operations. Based on reports from previous works, this report also presented potential strategies to achieve a significant reduction in GHG emissions for both the electricity grid and fossil fuel refining processes.

1. Literature Review

The transportation sector has a significant contribution to global GHG emissions. In 2016, the energy sector contributed 73.2% of global GHG emissions, industries (chemicals and cement) contributed 5.2%, waste (landfills and wastewater) totaled 3.2%, and agriculture, forestry, and land use produced 18.4% [1]. Out of the 73.2% of GHG emissions from the energy sector, 24.2% comes from industries, 16.2% from transportation, 17.5% from energy used in buildings, 7.8% from unallocated fuel combustion, 5.8% from fugitive emissions from energy production, and 1.7% from energy used in agriculture and fishing. Emission from road transport alone is 11.9% out of the 16.2% for transportation. Citing the International Energy Agency, IEA 2021 [2], the United Nations (UN’s) 2021 global status report for buildings and construction [3] reported that, in 2020, the transportation sector had a 23% share of global CO₂ emissions. The international energy agency [2] mentioned that for the transport sector, there is a need for a major transformation that includes efficiency improvement and a shift from oil to electricity and low-carbon fuels. “The IEA’s Net Zero Emissions by 2050 Scenario (NZE) is a pathway for the global energy sector to achieve net zero CO₂ emissions by 2050, while also achieving universal energy access by 2030 and major improvements in air quality” [2]. A reduction in emissions in the transportation industry will have a good impact on the efforts to reduce global emissions. In this plight, electric cars are seen as good alternatives, primarily because consumers do not see any emissions while driving electric cars. However, a significant amount of emissions is produced by some electricity grids. Some scholars [4] performed a high-resolution emission inventory for a populated middle eastern city using a bottom-up approach. Among other things, it was reported that the emission of SO_x and NOx primarily came from the power plants contributing 97% and 56% of the total emissions, respectively. Electricity grids are located far away from many end users. Power grids often transport electrical energy over long distances and between many locations. Understanding the patterns of production and consumption of electricity is a necessary first step toward reducing the health and climate impacts of associated emissions. Electricity has a large fraction of emissions from fossil fuel consumption [5]. The electricity to power most electric vehicles comes from the grid. The electrification of passenger road transport and household heating features is a major component of current and planned policy frameworks for GHG emissions reduction targets [6]. Electric cars have the potential to reduce carbon emissions, reliance on imported oil, and local air pollution, but the carbon reduction potential for electric cars depends on where they are charged [7]. Some scholars [6] analyzed current and future emissions trade-offs in 59 world regions with heterogenous households by combining bottom-up life cycle assessment and forward-looking integrated assessment model simulations. The scholars found that in 53 world regions, under the current carbon intensities of electricity generation, heat pumps and electricity are less emission-intensive than fossil-fuel-based alternatives. A previous report [7] noted that where power generation is dominated by coal, the emissions from electric cars are equivalent to average petrol cars, but they result in less than half the emissions of the best petrol hybrids in countries with low-carbon power. When it comes to behavioral changes or policies that shift electricity demand and affect new sources of clean generation, the effect on GHG emissions is highly dependent on the emission rates of the specific sources of generation that are displaced or ramped up in response [8]. In order to maximize carbon reduction emission potentials, a report [7] recommended that electric cars be used with low-carbon power.

1.1. Location Factors and Carbon Intensity of Electricity Generation

The low-carbon development of the electricity industry plays a significant role in national carbon-neutral goals [9]. The environmental quality of electricity through the electricity grids varies by location, time of day, and season [5]. The carbon intensity of electricity generation in China was 549.29 gCO₂/kWh in 2021, [10]. Regarding three grid interconnections in the US, a previous study [8] noted that the average emissions are uniformly lowest in the West and highest in Texas. In 2019, that report indicated that the average emissions are 0.72 pounds of CO₂ per kWh in the West, 0.88 in the East, and 1.0 in Texas. This is equivalent to 0.37 kgCO₂/kWh in the West, 0.399 kgCO₂/kWh in the East, and 0.454 kgCO₂/kWh in Texas. To a large extent, the promise of many electricity-shifting policies for emission reduction depends on how electricity generation will change in the future. The success of many policies in this regard is dependent on transmission to more low-emission sources of generation [8]. Canada’s energy regulator [11] reported that because of its size and reliance on coal-fired generation, Alberta’s electricity sector produces more GHG emissions than any other province. Furthermore, 52% of GHG emissions that are generated from Canadian power stations come from Alberta. In 2020, Alberta generated 590 g of CO₂e per kWh (gCO₂e per kWh) electricity. This was a 35% reduction from the 2005 level for the province (CER, 2022). Saskatchewan’s electricity sector has the second highest amount of GHG emissions in Canada, primarily because of its reliance on fossil fuel-based generation. The GHG emission from Saskatchewan’s electricity grid is 580 gCO₂e/kWh in 2020 [12]. Manitoba has 0.1% of total Canadian GHG emissions from power generation. In 2020, GHG emission from Manitoba’s electricity grid was 1.1 gCO₂e/kWh [13]. In 2020, Ontario’s electricity power had 25 g of CO₂e per kWh [14]. In 2020, the GHG from Quebec’s electricity grid was 1.5 gCO₂e/kWh. This is a 61% reduction from the province’s 2005 level of 3.8 gCO₂e/kWh. For Canada, the national average in 2020 was 110 g CO₂e/kWh [15]. The utilization of renewable energy plays an important role in electricity development [9]. “In 2020, Quebec’s power sector generated 0.4 MT CO₂e emissions, which represents 0.5% of Canada’s GHG emissions from power generation” [15]. In the 1990s, the global carbon intensity of electricity generation was approximately 900 g/kWh. This started to decrease in the 2000s and reached approximately 800 g/kWh by 2011 [16]. In order to maintain the 2-degree climate change target, it was reported that a short-term target of 600 g/kWh needs to be achieved in the electricity generation sector by 2020 [16]. In a study on high-resolution emission inventory for a city in the middle east, scholars [4] reported that on-road vehicles, power plants, and industries have the largest share of total particulate matter emissions at 45%, 35%, and 18%, respectively. On-road vehicles were seen as the major source of volatile organic compounds VOC emissions at 82% of the total annual emissions. While some VOC emission spots are related to gas stations, CO and VOC emissions are mainly from areas with high traffic. SO_x emissions are concentrated primarily in the areas of power plants. The report noted that power-generating sources are the sources that contribute most to GHG emissions. There are more than 30,000 biomass and fossil-fuel-burning power plants that are now operating worldwide [17]. This study recommends more effort towards GHG reduction (especially through GHG capture technologies and reprocessing of emissions of concern to beneficial substances for the global ecosystem). This study presents a framework for the evaluation of GHG emissions from electric cars and fossil-powered cars. Further research prospects for improvements in emission reduction efforts are also presented. The discussion in the following sections explores energy production for electric cars, a description of global warming potential equivalence, components of exhaust outlets of internal combustion engines, components of exhaust gases for power plants, carbon capture technologies, an evaluation of emissions from various energy sources, a description of a system dynamics model for a more holistic evaluation of the emissions, the carbon tax systems, GHG emission reduction programs, the usefulness of certain components of GHG emissions, opportunities that exist from ending gas flaring, conclusions, and recommendations.

1.2. Energy Production for Electric Cars

Electricity is generated from various renewable and non-renewable sources. While certain sources such as solar, wind, and hydropower are considered renewable, electric power from fossil fuels such as coal, natural gas, etc., is considered non-renewable. Virtually all electricity produced in Quebec and Manitoba comes from renewable sources. The GHG emissions of various fossil fuels differ. Coal is seen as a high-carbon-emitting power source among the fossil fuels that are used in electricity production. Meanwhile, the cost of other alternatives can have an impact on what the electricity producer may decide to use. IEA reported that in response to soaring prices of natural gas, some countries revert back to the use of coal. This is expected to result in an increase in global CO₂ emissions [18]. While a gradual transition to renewable energy is being considered in various places, an important research question is, “can the emissions from the electricity power stations be significantly reduced with the implementation of efficient GHG emission capture technologies”? If efficient GHG capture technology is implemented, there will be a lower economic and social impact on families, as the transition can be smoother and more gradual without excessive GHG emissions.

GHG Emissions That Are Associated with Power Generation for Electric Vehicles

Citing some previous works, the environmental protection agency (EPA) [19] reported that the national average carbon dioxide output rate for electricity that was generated in 2019 was 884.2 lbs CO₂ per megawatt-hour. Assuming transmission and distribution losses of 7.3%, this translates to 953.7 lbs CO₂ per megawatt-hour MWh for delivered electricity. This is equivalent to 0.95371 lbsCO₂ per Kilowatt-hour KWh = 0.433 kgCO₂/kWh (i.e., “884.2 lbs CO₂/MWh × 1 metric ton/2204.6 lbs × 1/(1–0.073) MWh delivered/MWh generated × 1 MWh/1000 kWh × = 4.33 × 10⁻⁴ metric tons CO₂/kWh”). The calculations of GHG per mile for US vehicles is 8.89 × 10⁻³ metric tons CO₂/gallon gasoline × 1/22.2 miles per gallon car/truck average × 1 CO₂, CH₄, and N₂O/0.994 CO₂ = 4.03 × 10⁻⁴ metric tons CO₂e/mile [19]. In addition, the GHG emissions that are associated with the extraction, processing, and transport of fuel that is used to provide energy to the power plants should be accounted for when calculating the GHG emissions for electric vehicles from a more holistic perspective (when the electricity for the electric vehicles is from GHG-emitting power plants). Considering the fact that GHG emissions are associated with various industrial processes, including those that are geared toward electricity production, carbon capture technologies are gaining attention.

1.3. Global Warming Potential, GWP, Carbon Dioxide Equivalence, and CO₂eq

The greenhouse gas inventory is more complete if all GHGs are included rather than only CO₂. Global warming potential (GWP) is a term that is used to describe the relative potency of a greenhouse gas (molecule for molecule) considering how long it remains active in the atmosphere [20]. The global warming potential (GWP) of a gas is the amount of warming that a gas causes over a specific period of time (normally, this is over 100 years). Greenhouse gas equivalent (CO₂e) is used to describe the different GHGs in a common unit. CO₂e indicates the amount of CO₂ that will have an equivalent global warming impact [21]. The commonly observed GHGs are CO₂, CH₄, N₂O HFCS, PFCS, and SF6. According to IPCC inventory guidelines, the GWP of CO₂ is set to a standard value of 1. For a 100-year evaluation period, the GWP value for CH₄ is 25, N₂O is 298, HFCS is 1430, PFCS is 12,200, and SF6 is 22,800 [22]. With CO₂ having an index value of 1, the GWP for all other gases is the number of times that they cause more warming than CO₂, e.g., 1 kg of Methane = 25 kgCO₂eq [21]. Some researchers [22] also presented a table that indicated the GWP for a 20-year evaluation period. It was reported that in a construction project, the emissions of hydrofluorocarbons, perfluorocarbons, and sulfur hexafluoride are extremely low and negligible. CO₂, CH₄, and N₂O are considered the primary emitted gases. During the construction stage for precast piles, the carbon emissions of construction machinery are primarily caused by energy consumption such as electricity, diesel, and gasoline. The emissions are calculated based on the carbon emission factors of machinery and equipment and energy consumption using diesel, gasoline, and electricity. The scholars [22] expressed the carbon footprint as follows:

$$\mathrm{Carbon} \mathrm{footprint} = \mathrm{Activity} \mathrm{level} \mathrm{data} \times \mathrm{Carbon} \mathrm{emission} \mathrm{factor}$$

Referencing a previous work, the EPA [19] stated that 8887 gCO₂ emission/gallon of gasoline consumed was the agreed upon common conversion by some stated agencies. This is approximately 2.35 kgCO₂/L of gasoline. For diesel, 10,180 gCO₂/gallon was mentioned. This is approximately 2.69 kgCO₂/L of diesel. For passenger vehicles in 2019, the ratio of carbon dioxide to total greenhouse gas emissions (including carbon dioxide [CO₂], methane [CH₄], and nitrous oxide [N₂O]) expressed as carbon dioxide equivalents for passenger vehicles is 0.994. Carbon dioxide equivalence for a gasoline-powered passenger vehicle will be = (8887 gCO₂ per gallon)/0.994 = 8.94 kgCO₂e/gallon. This is approximately 2.36 kgCO₂eq/L for gasoline. The interest in GHG emission reduction is not only observed in the transportation sector. There is an increase in the industry’s interest in carbon emissions during construction stages [22]. However, transportation cuts across various industries as, often, there is a need for the movement of goods and services from one point to the other. A previous study used life cycle analysis (LCA) to study the carbon footprint of the precast concrete pile during the construction of a building. The goal of an LCA is to assess the environmental impact of a system or product. The study divided the carbon footprints of precast concrete piles into three sources: Material transportation, construction equipment, and office area [22]. The reduction of GHG emissions from the exhaust of construction equipment and emissions that are associated with the operation and maintenance of various construction offices will result in a reduction of GHG emissions in the construction industry. In a similar manner, the reduction of GHG emissions from transportation operations for construction work will have a positive impact on the reduction of emissions in the construction industry. In an effort to establish a framework for the evaluation of GHG emissions that are associated with both electric vehicles and fossil-powered vehicles, it is important to determine what the components of these emissions are.

1.4. Components of the Exhaust Outlets of Internal Combustion Engines

Various studies have attempted to identify the components of exhaust gases from internal combustion engines. A previous work [23] reported that the constituents of internal combustion engine exhaust gases include major constituents that are greater than 1% (water, H₂O, carbon dioxide, CO₂, nitrogen, N₂, oxygen, O₂, carbon monoxide, CO, and hydrogen, H₂) and minor constitutes (less than 1%) that include oxides of sulfur, SO₂, SO₃, hydrocarbons, C_nH_m, carbon monoxide, hydrogen and smoke, oxides of nitrogen, NO, NO₂, aldehydes, HCHO₂, organic acids, HCOOH, alcohols, CH₃OH, etc., The study presented threshold limits for continuous 8-h exposure for carbon dioxide, carbon monoxide, sulfur oxides, formaldehyde, and nitrogen oxides. The study also presented the results of a study in which exhaust-gas samples were obtained from gasoline, diesel, and propane-powered motor coaches of similar passenger capacity under idling, accelerating, cruising, and decelerating driving conditions. The samples were analyzed for oxides of nitrogen, carbon monoxide, formaldehyde, and hydrocarbons. The authors reported that the difference in emissions for oxides of nitrogen, formaldehyde, and hydrocarbons by the three types of coaches that were evaluated was relatively small. Carbon monoxide and Hydrogen were reported as the primary constituents in spark ignition engines and minor constituents in diesel engines. The international agency for research on cancer (IARC) [24] mentioned that “the major products of the complete combustion of petroleum-based fuels in an internal combustion engine are carbon dioxide (13%) and water (13%), with nitrogen from air comprising most (73%) of the remaining exhaust”. A small portion of the nitrogen is said to be converted to nitrogen oxides and some nitrated hydrocarbons. Depending on the operating conditions, some excess oxygen may also be emitted. On the other hand, incomplete combustion results in the emission of unburnt fuel and lubricating oil, carbon monoxide, thousands of chemical components in gaseous and particulate phases, etc. Both gasoline and diesel are hydrocarbons; however, they contain some sulfur compounds too. Aerosol precursor gases that are primarily emitted from diesel engines include SO₂, SO₃, H₂SO₄, NO_x, H₂O, soot particles, and low and semi-volatile organic species. A large fraction of hydrocarbons is removed by oxidation catalysts, boosting SO₂ to SO₃. SO₃ reacts quickly with exhaust water (H₂O) to form sulphuric acid [25]. Combustion of the fuel in the air also allows for the formation of chemical compounds with other components of the air. The IARC [24] cited a previous work that indicated that “gasoline engines are designed to operate at a nearly stoichiometric ratio (an air: fuel ratio of approximately 14.6:1) and diesel engines operate with excess air (an air: fuel ratio of approximately 25–30:1)”. Sulfur compounds from fuels such as diesel and gasoline cause air pollution. To address this issue, large-scale oil refinery processes remove the majority of sulfur from fuel down to a government-mandated level [26]. Some researchers [27] developed a technique that has the potential to further reduce sulfur content to a fraction of the amount that is mandated by government regulations. The scholars claimed that “a robust potassium (K) alkoxide (O)/hydrosilane (Si)-based (‘KOSi’) system efficiently desulfurizes refractory sulfur heterocycles. Subjecting sulfur-rich diesel (that is, [S]∼10,000 ppm) to KOSi conditions results in a fuel with [S]∼2 ppm, surpassing ambitious future governmental regulatory goals set for fuel sulfur content in all countries”. Some compounds and classes of compounds in the exhaust of vehicle engines include the gaseous phase (acrolein, ammonia, benzene, 1,3 butadiene, formaldehyde, formic acid, heterocyclics and derivatives, hydrocarbons C1-C8 and derivatives, hydrogen cyanide, hydrogen sulfide, methane, methanol, nitric acid, nitrous acid, oxides of nitrogen, polycyclic aromatic hydrocarbons and derivatives, sulfur dioxide, and toluene) and the particulate phase (heterocyclics and derivatives, hydrocarbons and derivatives, inorganic sulfates and nitrates, metals such as lead and platinum, polycyclic aromatic hydrocarbons, and derivatives) [28]. Citing a previous work, the IARC [24] noted that the concentration of chemical types in vehicle exhaust depends on several factors, including the operating condition of the engine, the type of engine, the composition of the fuel and lubricating oil, and the emission control system. Some scholars [29] cited previous works that indicated that as the torque and rotating speed of the engine change due to the variability of vehicle speed, acceleration, slope, etc., the exhaust mass flow rate and the concentration of gaseous pollutants (NO_x, CO, HC, etc.) that are emitted in internal combustion engines changes.

1.5. Some Components of Exhaust Gases for Power Plants

A significant amount of CO₂ emissions is generated from fossil fuel power plants [30]. Depending on the composition of the fuel, complete and incomplete combustion of fossil fuel can produce various chemical elements or compounds from its original composition and elements in the air. In electricity generation, high-sulfur heavy oil is partially used. Emissions from power plants include NO_x, SO_x, and TSP [4]. At coal-fired power plants, the concentration of SO₂ in flue gases is typically 700–2500 ppm [31]. Mercury is one of the emissions of concern from coal-fired power plants. Some researchers [32] cited a previous work that indicated that coal-fired power plants that produce more than 300 GW in the US are known to be a major anthropogenic source of domestic mercury emissions, and another indicated that the U.S. EPA promulgated the clean air mercury rule to limit and reduce mercury emissions from the plants. The scholars reported that with low-rank coals, halogenated powdered activated carbon (PAC) appears to provide high levels of mercury capture. A previous study [33] presented the LCI result of coal combustion in a pulverized coal PC wall-fired dry bottom boiler. To generate 1 MW h of electricity, the flue gas contains N₂, CO₂, H₂O, O₂, PM, SO₂, PM10, SO₃, S, NO, NO₂, CO, HCL, HF, CH₄, N₂O, and TOC. The study noted that other components of the flue gas include antimony, arsenic, beryllium, cadmium, chromium, cobalt, lead, manganese, nickel, selenium, zinc, copper, thallium, vanadium, barium, silver, elemental mercury, Hg0, oxidized mercury Hg2+, and particle-bound mercury Hgp. In addition to some steam releases, solid releases include bottom ash, unburnt carbon, and S (bottom ash). The inputs are Coal, N₂, O₂, and some energy. The quantities for these were reported in the study. The study noted that ecotoxicity and human toxicity are mainly caused by trace matter in particulate matter or bottom ash [33]. SO Energy International [34] noted that the composition of flare gas often includes traces of hydrogen sulfide, heavy hydrocarbons, and carbon dioxide. NOx is an extremely polluting gas that is produced during the combustion of biomass and fossil fuels [35]. Efforts to control GHG emissions from power plants can also be beneficial in the control of air pollutants. A researcher [36] described the effects of various air pollutants on human health. Another scholar [37] also cited various previous works that described the effect of air pollution on human health. The emission inventory is a tool that is widely used to investigate policies and interventions that are related to air pollution [4]. This study recommends a periodic emission inventory and reporting of the results for all industries with gaseous emissions. This will provide the public with better knowledge of the constituents of the gaseous emissions in the community. It will also help to determine the best strategy for emission control for various industries.

1.6. Carbon Capture Technologies

Widespread interest in the capture and sequestration of carbon dioxide from fossil fuel power plants (as a potential means of controlling GHG emissions) is increasing [31]. Canada energy regulator CER [12] reported that “In 2014, 139 MW of coal-fired capacity at the Boundary Dam station was retrofitted with carbon capture and storage technology that is capable of capturing and storing up to 1.0 MT CO₂ per year of emissions that would have otherwise been released. In 2020, over 0.7 MT were captured, and over 4.0 MT have been captured since start-up.” This further showed that good progress can be achieved in the effort to capture GHG emissions. More efforts to put these captured emissions into good use are recommended. Various governments are making efforts to reduce their GHG emissions. Some scholars [9] reported that the effort of the Chinese government in the promotion of the energy shift is expected to reduce the GHG emissions from the electricity grid to 376 gCO₂-eq/kWh by 2035. Geological storage for injected CO₂ is a promising technology for the reduction of emissions of CO₂ into the atmosphere [38]. The storage options that were mentioned in a previous study by the intergovernmental panel on climate change (IPCC) [39] include mineral carbonation, ocean storage, and geological storage. Some scholars [33] illustrated a procedure for a post-combustion CO₂ capture system in a power plant. The authors mentioned that the system described is able to capture 95% of CO₂ from power plants with post-combustion CO₂ capture. A previous work [31] gave an illustration of a flowsheet for CO₂ capture from flue gases using an amine-based system. Another study [40] also gave a schematic diagram of a coal-fired plant with carbon dioxide capture and storage (CCS). The scholars cited previous works that mentioned where CO₂ capture demonstration plants have been installed. Some researchers [30] mentioned three main technological routes for CO₂ capture from power plants (oxy-fuel combustion, pre-combustion, and post-combustion). The scholars noted that the application may reduce the net efficiency of a power plant by up to 14% and increase the cost of electricity by 30–70%. Other researchers [40] also mentioned that although carbon dioxide capture and storage (CCS) is a promising countermeasure against global warming, the installation of CCS into a power supply system causes a significant decrease in power output. Meanwhile, the specifications of a base case conventional power plant without CO₂ capture and the same power plant with an alternative post-combustion CO₂ capture that was assessed in the study by previous scholars [33] showed that the gross energy efficiency of a power plant is the same for the power plant before CO₂ capture and post-combustion CO₂ capture. The CO₂ capture rate was 95%, the SO_x removal rate was 99%, and the particulate matter removal rate is 99.97%. US Appalachian (bituminous) coal was referenced for this. For the power plant that was mentioned in the study (a 500 MW capacity), before and after, the power plant’s gross energy efficiency-LHV was 40%. Another study [40] indicated that an approximately 2% efficiency improvement can be expected by reducing the regeneration energy of the CO₂ scrubbing solvent by 1 GJ/t-CO₂. This shows a need for further research on how to improve the efficiency of power plants while implementing innovative carbon capture technologies. Citing previous works, the EPA [19] reported that the average carbon dioxide coefficient of natural gas is 0.0551 kgCO₂ per cubic foot. The average carbon coefficient of distillate fuel oil is 431.87 kgCO₂ per 42-gallon barrel. The average carbon dioxide coefficient of liquefied petroleum gases is 235.7 kgCO₂ per 42-gallon barrel. When electricity for electric cars is from GHG-emitting power stations, the GHG emissions from the electricity power station become an indirect GHG emission for the electric cars. In an effort to provide some clarity in comparison to the emissions from electric vehicles and fossil-fuel-powered vehicles, this study evaluated the expected emissions for vehicles powered by different types of energy for specific distances. An extension of the evaluation used system dynamics simulation modeling to evaluate how various technological improvements may affect emissions from both electric vehicles and fossil-powered vehicles.

2. Materials and Methods

The concern about air pollution and the resulting health effects in various communities around the globe necessitates that we take proactive action to improve the air quality in our environment. Air pollution is not limited to pollution on the road. There is a considerable level of air pollution from construction sites too. As part of a larger project, during this study, a construction site was visited to investigate the work processes. The work involves the use of equipment such as a backhoe excavator for excavation works, for the demolition of an existing building, etc. The work also involves equipment, material, and worker transport to and from the site. These tasks have their associated environmental impacts that can be evaluated through a life cycle analysis procedure. Some of the work on-site during the visit includes demolition, excavation, hauling of materials away from the site, shoring, and the establishment of connections to existing utilities. During the site visits, some distances were recorded based on questions from some of the workers (such as roundtrip distances for worker transportation, i.e., travel distance for the equipment operator to and from the site, the location for the dumping of demolished concrete, etc.) The estimated travel distance for the operator transport was used to evaluate what the GHG impact will be with alternative energy sources such as gasoline, diesel, and electricity in eight different regions. The GHG emissions that were used for regions A to H as mentioned in

Table 1. Comparison of GHG emissions for electric-powered, diesel-powered, and gasoline-powered pickup trucks for different communities.

Activities	Type of Vehicle	Round Trip Distance for 10 Days (km)	Energy Use Rate for Vehicle	Units	GHG: Diesel-Powered Vehicle (kgCO2eq/L)	GHG: Gasoline-Powered Vehicle (kgCO2eq/L)	GHG: Electric Powered Vehicle kgCO2eq/kWh	Total GHG for Manpower Transport (kgCO2eq)
Operator transport (Diesel)	Pick up truck A,	900	0.091	L/km	2.71	0	0	221.95
Alternative energy 1 (Gasoline)	Pick up truck B,	900	0.093	L/km	0	2.36	0	197.53
Alternative energy 2 (Electric): Region A	Pick up truck C,	900	0.373	kWh/km	0	0	0.59	198.06
Alternative energy 2 (Electric): Region B	Pick up truck C,	900	0.373	kWh/km	0	0	0.58	194.71
Alternative energy 2 (Electric): Region C	Pick up truck C,	900	0.373	kWh/km	0	0	0.549	184.30
Alternative energy 2 (Electric): Region D	Pick up truck C,	900	0.373	kWh/km	0	0	0.454	152.41
Alternative energy 2 (Electric): Region E	Pick up truck C	900	0.373	kWh/km	0	0	0.399	133.94
Alternative energy 2 (Electric): Region F	Pick up truck C	900	0.373	kWh/km	0	0	0.37	124.21
Alternative energy 2 (Electric): Region G	Pick up truck C	900	0.373	kWh/km	0	0	0.0015	0.50
Alternative energy 2 (Electric): Region H	Pick up truck C	900	0.373	kWh/km	0	0	0.0011	0.37

have been earlier mentioned in this article.

The evaluation presented in Table 1 and Figure 1 includes consideration of the ratio of CO₂ emissions to the total GHG emissions (including, methane, nitrous oxide, and carbon dioxide), expressed as carbon dioxide equivalents. For 2019, for passenger vehicles, the ratio of CO₂ to the total GHG was reported as 0.994 by the United States environmental protection agency EPA [19]. This was considered for both gasoline and diesel consumption. For gasoline, the amount of carbon dioxide per L is 2.35 kgCO₂/L. With consideration given to some other GHG gases, the carbon emission per L of gasoline = 2.35/0.994 = 2.36 kgCO₂/L. For diesel, the amount of carbon dioxide per L is 2.69 kgCO₂/L. With consideration given to some other GHG gases, Carbon emission per L of diesel = 2.69/0.994 = 2.71 kgCO₂/L. There was no note to indicate that GHG emissions from the extraction and processing of the oils were included in this calculation. However, these are also associated emissions that should be considered. When fossil fuels are used at electric power plants, there are emissions that are associated with the production and extraction of those fossil fuels too. Hence, a more holistic evaluation of the emissions for both electric vehicles and fossil-powered vehicles will include all the emissions from the ‘cradle’ (material extraction and processing) to the ‘grave’ (final point of use of the energy). The comparison of GHG emissions for fossil-powered vehicles and electric vehicles below does not include the emissions that can be associated with the extraction, processing, and transportation of diesel and gasoline to the gas stations before the sale of fossil fuel for cars. The system dynamic model in Section 4 shows a more holistic view of the interconnections between the emissions that are generated by fossil-powered and electric-powered vehicles. From a holistic viewpoint, given that emissions from industrial plants contribute to the overall GHG emissions of electric vehicles and fossil-powered vehicles, this study also proposed a strategy to ensure capturing and localized treatment of gaseous emissions from industrial plants. References were made to previous works on how some GHG emissions can be captured, absorbed, or converted to other forms.

2.1. Calculating GHG Emissions: Comparison of GHG Impacts from Transportation to Site Using Different Types of Energy

Natural resources Canada (NRCAN) provides an online tool that can be used to look up the fuel consumption for different vehicles [41]. For the site that was visited, the equipment operator travels to the site in a pickup truck. The roundtrip distance for the operator was 90 km per day. It was assumed that the pickup truck for the operator is made in the year 2022. The number of travel days to the site was also assumed to be 10 days. Using the online tool, the fuel consumption rating for a 2022 model of the truck for a combination of city and highway is 9.1 L/100 km. This means that for 1 km of travel, 0.091 L of diesel will be used. As described above, the CO₂eq. for diesel is approximately 2.71 kgCO₂ eq/L.

GHG emissions per L multiplied by the distance that is covered per L gives the GHG emissions per unit of distance.

$$0.091 \left(\mathrm{liters}/\mathrm{km}\right)\times 2.71{\mathrm{KgCO}}_2\mathrm{eq}/\mathrm{liter} =0.247{ \mathrm{kgCO}}_{2 \mathrm{eq}}/\mathrm{km}$$

This GHG impact per L is expected to change in the future as the efficiency of GHG-capturing technologies increases. At that time, there will be a need for an assessment of the efficiency of the GHG capture mechanism to determine the extent of GHG that escapes the system (if any does escape).

2.1.1. Electric-Powered Pick-Up Truck

A 614-horsepower all-wheel drive pickup has a target range of 200 miles (321.869 km) through a 120-kWh battery and 75 min fast-charging capability [42]. This translates to 0.373 kWh/km as shown below. The energy use rate for electric vehicles, $E{N}_{elec}$, is the total distance traveled, $d_t$, divided by the amount of electricity that is required to cover that distance, $e_t$.

$$E{N}_{elec}=\frac{d_t}{e_t}$$

$$120 \mathrm{kWh} \mathrm{for} 200 \mathrm{miles} \mathrm{i}.\mathrm{e}., \mathrm{for} 321.869 \mathrm{km}$$

$$\mathrm{Energy} \mathrm{use} \mathrm{rate} \mathrm{for} 1 \mathrm{km} =\frac{120 \mathrm{kWh}}{321.869 \mathrm{km}}=0.373 \mathrm{kWh}/\mathrm{km}$$

In 2020, the GHG emitted in the generation of electric power for a province was 590 gCO₂e per kWh = 0.59 kgCO₂e/kWh. Using 0.373 kWh per km for an electric pickup truck, for a 900 km trip and 0.59 kgCO₂eq/kWh, there will be 198.063 kgCO₂e in emissions, i.e., the indirect emission associated with electric vehicles is the product of the emission associated with the manufacture of 1 kWh with the number of kilowatt hours that is required to move the vehicle through the travel distance. For a distance of 900 km (illustrated in Table 1), the GHG emission is

$$0.373 \left(\frac{\mathrm{kWh}}{\mathrm{km}}\right)\ast 0.59 \left(\frac{{\mathrm{kgCO}}_2\mathrm{eq}}{\mathrm{kWh}}\right)\ast 900 \mathrm{km} =198.063{ \mathrm{kgCO}}_2\mathrm{eq}$$

Note that the power usage rate for various vehicles differs, hence, there will be different results with different power usage. While the above truck can drive approximately 2.7 km per kWh of electricity, there is a report of an electric vehicle in which 1 kWh can drive for 6.4 km [43]. This means that the energy use rate of that electric car is approximately 0.156 kWh/km.

2.1.2. Gas (Gasoline)-Powered Trucks

The Ford Media Center [44] mentioned that Ford’s F-150 with 3.5-L PowerBoost (TM) V6 (gas-powered full-size light-duty pickup) consumes 9.3 L per 100 km on a 4 × 2 model. The 4 × 4-equipped PowerBoost F-150 has a combined fuel consumption rating of 9.8 L per 100 km. Specifically, 9.3 L per 100 km translates to 0.093 L/km. For a distance of 900 km as presented in Table 1, the GHG emission for the truck is expected to be

$$0.093 \left(\frac{\mathrm{liters}}{\mathrm{km}}\right)\ast 2.36 \left(\frac{{\mathrm{kgCO}}_2\mathrm{eq}}{\mathrm{liter}}\right)\ast 900 \mathrm{km} =197.53{ \mathrm{kgCO}}_2\mathrm{eq}$$

2.1.3. Diesel-Powered Engines

A previous report indicated that while gasoline engines produce 2.3 kg of CO₂ per L of gasoline, diesel engines yield 2.7 kg of CO₂ per L of diesel fuel used [45]. The calculation below includes an allowance for some of the other GHGs, i.e., as mentioned earlier, for 2019, for passenger vehicles, the ratio of CO₂ to the total GHG was reported as 0.994 by the EPA [19]. This was assumed to hold for the estimations of GHG gases in these illustrations. For a distance of 900 km, as illustrated in Table 1, the GHG emission for the 2022 version of the operator’s truck is expected to be

$$0.091 \left(\frac{\mathrm{liters}}{\mathrm{km}}\right)\ast 2.71 \left(\frac{{\mathrm{kgCO}}_2\mathrm{eq}}{\mathrm{liter}}\right)\ast 900 \mathrm{km} =221.95{ \mathrm{kgCO}}_2\mathrm{eq}$$

3. Results

Table 1 shows that both electric-powered and fossil fuel-powered vehicles have associated GHG emissions. This can also be seen in Figure 2 (except for the regions that have very low GHG emissions from their electric grid). In region A, while a diesel-powered pickup truck using 0.091 L of diesel per kilometer has more GHG emissions than an electric-powered pickup truck (with an energy consumption of 0.373 kWh/km), a gasoline-powered pickup truck with 0.093 L of gasoline per km has slightly less GHG emissions than an electric vehicle (with energy consumption of 0.373 kWh/km).

Opportunities for the reduction of GHG emissions from fossil fuel-powered vehicles exist in:

• Reducing the amount of fuel used per distance traveled.
• Implementing GHG emission capture technology into fossil fuel-powered vehicles to greatly reduce or eliminate GHG emissions from these vehicles.

4. Discussion

Regions with very low GHG emissions from the electricity grid (such as regions G and H) have significantly low GHG emissions that are associated with their electric vehicles. Emission reduction opportunities exist for both fossil-powered and electric-powered vehicles. A similar evaluation can be performed for material delivery, equipment delivery, and even equipment used on the site to know the total GHG emissions that are associated with the work. As more technological innovations arise for GHG emission capture and reprocessing, the impact of GHG emissions from different vehicles can be re-assessed while considering the efficiency of the GHG emission reduction technologies. The system dynamics model that is described below allows for a more holistic evaluation of the GHG emissions for both electric cars and fossil fuel-powered cars.

4.1. System Dynamics Modeling for Comparison of GHG Emissions from Electric and Fossil Fuel Cars

A system dynamics model can be used as a basis for decisions on the impact of GHG for both electric vehicles and fossil fuel-powered vehicles. The system dynamics model shown below was developed using Vensim software for illustrative purposes only.

4.1.1. GHG Associated with the Operation of Electric Vehicles

The GHG emissions that are associated with electric vehicles will include a sum of all the GHG emissions that are associated with the extraction, processing, transportation, and use of the fuel at the electricity power station. The emissions from the power stations can be mitigated by the implementation of adequate GHG capture and processing system.

4.1.2. The Efficiency of GHG Emission Reduction Technologies

GHG emission reduction technologies have a tendency to help reduce the GHG impacts on the environment. The efficiency of various technologies that are employed at power plants, and in vehicles may be different. It is important to have an accurate evaluation of the level of efficiency of each technology. It is also important to do a periodic check for the status of the efficiency of the technology.

$$GH{G}_{out}=GH{G}_{in}-\left(R_{in}\ast GH{G}_{in}\right)$$

where $GH{G}_{out}$ is the final GHG output from the system, $GH{G}_{in}$ is the GHG from the system before the application of the GHG emission reduction technology, $R_{in}$ is the GHG reduction potential of the technology that is employed to reduce GHG emissions. When the GHG reduction potential is 100%, i.e., =1, there will be zero GHG emissions. If the GHG emission reduction potential is 0.75 (i.e., 75%), the system still has 25% remaining GHG emissions that need to be further addressed. GHG impacts per unit of electricity reaching the consumer from power plants using non-renewable energy sources $GH{G}_{i.cons}$ is the amount of electricity reaching the consumer, $E_{cons}$ divided by the total GHG output after considering the efficiency of GHG reduction technologies $GH{G}_{out}$.

$$GH{G}_{i.cons}=\frac{E_{cons}}{GH{G}_{out}}$$

Note that at this point some technologies such as CO₂ emission reduction for fossil fuel vehicles are still anticipated for the future. However, the catalytic converter is presently used in the control of some of the emissions of concern.

4.1.3. For Fossil Fuel-Powered Vehicles

Similar to electric vehicles, the GHG emissions from gasoline combustion (after considering technological innovations for GHG emission reduction) can be expressed as:

$$GH{G}_{out.g}=GH{G}_{in.g}-\left(R_{in.g}\ast GH{G}_{in.g}\right)$$

where $GH{G}_{out.g}$ is the final GHG output from the internal combustion system for gasoline-operated vehicles, $GH{G}_{in.g}$ is the GHG from the system before the application of the GHG emission reduction technology, $R_{in.g}$ is the GHG reduction potential of the technology that is employed to reduce GHG emissions in the gasoline combustion system.

Figure 3 depicts a comparison of GHG impacts for electric and gasoline-powered vehicles (with the inclusion of illustrations for GHG reduction efficiency through technological innovations in some of the processes). Depending on the actual procedures that are followed in the plant, the GHG efficiency reduction potential can be adapted for any individual fuel use at the electricity power plants, petroleum refining plants, and other industrial processes. Note that although Figure 3 showed a system dynamic model comparison for gasoline-powered vehicles and electric vehicles, for a comparison of other fossil fuels, gasoline can be replaced with any fossil fuel that is used for the vehicle. The relevant GHG emissions for the fuel can also be updated in the model. The climate and health impacts that are associated with the production, consumption, and exchange of electricity should be given close attention [5].

The Vehicle of Choice

The vehicle of choice in terms of environmental impact is the one with the minimal amount of emissions of concern (i.e., minimum emissions from either electric-powered vehicle $GH{G}_{ev}$, or fossil-powered vehicle, $GH{G}_{fpv}$).

$$Vehicle of choice V_{ch}=MIN\left(GH{G}_{ev},GH{G}_{fpv}\right)$$

The system dynamic model allows for the simulation of various scenarios over a wide range of values.

The above system dynamic model can be used to show that:

The GHG impact of the electric vehicle is dependent on the GHG impact of the associated fuel that is used in the production of electricity.

The GHG impacts for electric vehicles will increase as the GHG emissions increase for the extraction and processing of the fuel that is used to power the electricity generation station.

The GHG impacts for electric vehicles will increase as the GHG emissions increase in the electricity generation processes at the electricity power station.

The GHG impacts for electric vehicles (from the power stations with non-renewable power sources) will reduce as the efficiency of the GHG reduction technologies increase.

The GHG impacts of fossil fuel-powered vehicles will increase as the GHG emissions increase for the extraction and processing of fossil fuel.

The GHG impacts (from tailpipes) of fossil fuel-powered vehicles will reduce as the efficiency of GHG emission reduction technologies is improved in fossil-powered vehicles.

Note that, depending on the inputs, even though an electric-powered vehicle may show less GHG impacts in some situations, from a sustainability perspective, other factors such as social and economic will still need to be considered while the world is gradually transitioning to renewable energy forms. From the perspective of expected impacts from GHG emissions, the vehicle of choice will be the one with lesser GHG emissions from a holistic point of view. If desired, the model can be further expanded in future studies to include GHG from the manufacturing of various industrial components that are used in the production of vehicles, and in the production of equipment for the generation of electricity. The model can also be expanded to include expected emissions from wear and tear such as tire wear, road abrasion, and brake wear. A previous report [46] mentioned that this may also be a concern for GHG emissions. The illustrative system dynamic model can be expanded to include GHG impacts from any source of power that is used for the production of electricity, as well as the extraction and refining of fossil fuels. A holistic evaluation of the GHG impacts from an entire system perspective will provide a better understanding of GHG impacts from both electric vehicles, as well as fossil fuel-powered vehicles. This can also help to identify potential areas of opportunity for improvement. The impacts from power plants using renewable energy may include impacts from the production of equipment used for the generation of energy (such as solar panels, wind turbines, hydroelectric turbines, etc.). Similarly, the GHG for power stations that use fossil fuels can include GHG from the manufacturing of equipment used for electricity generation in those stations. For simplicity’s sake, this may be ignored, except if found to be excessive. The GHG impact from the extraction and refining of fossil fuels may be derived by a fair allocation of the amount of GHG from the upstream operations to each unit of fuel that is used for transportation, industrial equipment, and other fossil-fuel-powered equipment that is used on various sites. If electric-powered vehicles use electricity from the grid powered with fossil fuels, such as natural gas, coal, petrol, diesel, etc., these sources have associated GHG impacts. There are opportunities for improvements for both electric-powered vehicles and fossil fuel-powered vehicles. If fossil-powered vehicles can show that the emissions generated by the vehicles (either through improved fuel economies or emission reduction technologies) are less or equivalent to those that are generated by electric vehicles powered by GHG-emitting electric power stations, this will bring the vehicles in these two categories to a closer basis for comparison.

4.2. Exploration of Ways to Reduce GHG Emissions for Both Electric Vehicles and Fossil-Powered Vehicles

The present design of fossil-fuel-powered vehicles and equipment puts them at a disadvantage because they allow more concentrated levels of emissions to be brought closer to people in residential communities through tailpipe emissions. In addition to the exploration of innovative emission reduction technologies, this study recommends the exploration of emission-capturing systems for various fossil-powered vehicles. Another concern for the use of ‘non-renewable’ energy sources such as fossil fuels is the concern about the depletion of these resources in different communities. While sustainability principles in the broad sense are three-dimensional, making an effort to ensure a balance in the economic, environmental, and social well-being of people is important. Sustainability principles also consider a wise use of resources in such a way that future generations will have access to the resources they need. Hence, as a scholar [47] mentioned previously, reserving non-renewable energy for use only in circumstances where it may not be technologically or economically feasible to use renewable energy will be a good approach, i.e., the eventual goal will be to reach a condition in which ‘non-renewable’ energy will be used only for situations in which it is not technically feasible to use renewable energy sources at that point in time (according to the technological development of the day). A gradual transition from non-renewable energy sources over a long period will be a feasible plan that should allow for good economic adjustments. In the meantime, the development and implementation of technologies to greatly reduce various environmental impacts will be commendable. Although electric-powered vehicles also have associated GHG emissions from the electricity grid, in reference to air quality close to traffic intersections, except when the technology to capture emissions from tailpipes of fossil-powered vehicles is employed, electric-powered vehicles may be preferable to fossil-powered vehicles regarding a reduction in the concentration of emissions for people that live, attend schools, or work close to major roads and traffic intersections. This study recommends further research and the implementation of technologies to capture emissions from fossil-powered vehicles.

In an effort to minimize emissions for various transportation operations including the transportation of people, materials, and equipment to and from construction sites, this study showed how to compare the standard GHG emissions of fossil fuel-powered vehicles for different transportation alternatives. The method can also be adapted for a comparison of emissions for equipment that uses alternative forms of energy. In the goal to minimize global emissions and achieve better air quality in the global ecosystem, a great deal of work needs to be performed. It has been established that there are associated emissions from many electric power stations. Similarly, there are associated emissions with fossil-power vehicles. As the emissions that are emitted during the generation of electricity at power stations are included in the calculations of total emissions for electric vehicles, likewise, emissions that are associated with the processing of crude oil to obtain each unit of fuel (such as gasoline, diesel, propane, etc.) should be included in the overall emissions for vehicles that are powered by fossil energy. The emissions from the resource extraction and processing of fuel for various power stations should also be considered in the overall emissions for each unit of electricity that reach the consumer.

Although petrol and diesel are hydrocarbons, previous studies have shown that these fuels also contain some sulfur; hence, the exhaust gases can contain compounds that are more than compounds of hydrogen, nitrogen oxygen, and other elements in the air. Further study is recommended to determine the exact components of exhaust gases from electric power stations (with each type of energy that is used). Similarly, further research is recommended in the determination of the components of the exhaust gases that are associated with the extraction and refining of fossil fuels, as well as exhaust gases that are associated with different makes and models of vehicles.

4.2.1. Towards Zero-Tailpipe Emissions in Internal Combustion Engines of Fossil Fuel-Powered Vehicles

Various technologies have been devised to reduce emissions from vehicles. A Three-way catalytic converter is a pollution control product that has been widely used to reduce the emissions of total hydrocarbon (THC), Nitrogen oxides (NOx), and carbon monoxide (CO) from vehicles. However, as a result of aging, the efficiency of three-way catalytic converters can have a significant impact on their environmental benefits [48]. As innovative methods of emission control evolve, zero emissions in internal combustion engines may eventually reach a stage where all exhaust emissions that we presently have are treated and recirculated for use in internal combustion engines (with very little residue for further reprocessing). Further research is recommended on this. However, in the meantime, capturing the emissions for treatment in external facilities is a possibility. This may involve the design and implementation of technologies that allow for the connection of exhaust pipes to temporary storage cylinders on the vehicle. It may also include air compression systems. With this method, a zero-tailpipe-emission system can be achieved. This requires further research and the implementation of technology that best achieves the goal. The development and implementation of a system such as this will help alleviate the concerns about GHG emissions from automobiles. It will also help reduce the concern about air pollution from tailpipes of fossil-powered automobiles. Better knowledge of the components of the exhaust gases from different sources will provide a better understanding of the treatment processes that these gases will be subjected to in order to ensure the adequate removal of hazardous chemicals from gaseous effluents from industrial operations, various vehicles, and machinery.

Further study is recommended on the flow rate of exhaust gases from various vehicles and machinery. Better knowledge of these flow rates will provide a better understanding of what is required to ensure adequate capturing of GHG emissions, the amount of temporary storage that is needed, and the timeline in which further actions are needed. Some researchers [23] mentioned that it is difficult to obtain direct measurements of the exhaust-gas flow rate of a moving vehicle. “Accordingly, it seemed advisable to use dilution metering technique” [23]. Some other scholars [29] developed a methodology for instantaneous average exhaust gas mass flow rate measurement. With MIVECO, the real driving emissions of light-duty vehicles can be determined [29].

Mitigation Strategies

To help reduce vehicle emissions, among other things, the choice of more efficient vehicles, the adoption of fuel-efficient driving habits, and avoiding idling (turning off the vehicle when not in use for more than 60 secs, when not in traffic) are recommended [45]. While N₂O and CH₄ produced by the engine (more potent than CO₂) can be reduced by the catalytic converter, CO₂ emissions cannot be reduced by the catalytic converter [45]. Logistical improvements to reduce the impact of GHG emissions can include the location of material supply for construction close to each other in a city. In this way, a customer may not have to drive long distances to find different construction materials from separate shops.

4.2.2. GHG Emission Reduction Programs in Various Places

Canada’s emission reduction plan includes the introduction of a price on Carbon starting at $20 per tonne in 2019 and rising to $170 per tonne in 2030, the launch of a $2 billion low-carbon economy fund and a $200 million climate action and awareness fund, working with key stakeholders on the hydrogen strategy for Canada, investment to grow clean fuels market through an energy innovation program and the $1.5 billion clean fuels fund, publishing proposed clean fuel regulations, and joining the global methane pledge to reduce methane emissions by at least 30% below 2020 levels by the year 2030 [49]. The UK government has a 10-point strategy for Net Zero. Some of the plans include (1) working with the grain of consumer choice, (2) ensuring the biggest polluters pay the most for the transition, (3) ensuring the most vulnerable are protected through government support in the form of energy efficiency upgrades, discounts to the energy bill, etc., (4) working with businesses to continue the delivery of deep cost reductions in low-carbon technology, and (5) subject to the security of supply, by 2035, the UK aims to be entirely powered by clean electricity [50]. Canada has a target to make 100% of light-duty cars and passenger truck sales zero-emission by 2035 [51]. If this is to be achieved, there is a need for a clear plan that will be reviewed every year to ensure that the project is on course to achieve the target. The United States also has various programs and strategies for GHG reduction. EPA 2022 mentioned GHG reduction initiatives such as the ENERGY STAR Program through a partnership with many private organizations, and this program offers technical information and tools that various consumers and organizations need to choose energy-efficient solutions and the best management practices. As a way to reduce the environmental impacts that are associated with conventional electricity use, the Green Power Partnership (GPP) program encourages organizations to use green power. The program already has many partner organizations. The Green Supplier’s Network from the U.S. EPA works with large manufacturers to engage their suppliers in low-cost technical reviews that can identify strategies for the improvement of process lines, the reduction of waste, and the more efficient use of materials. Regarding waste reduction and diversion strategies, the US EPA provides resources on waste reduction and recycling in the workplace, initiatives to reduce everyday trash, frameworks for food recovery programs, and guidance on starting or expanding a recycling collection program. To reduce methane emissions, the AgSTAR program by the U.S. EPA promotes the use of biogas recovery systems to reduce the emissions from livestock waste. Among other things, the program also provides some form of assistance to those who enable, implement, or purchase anaerobic digesters. In an effort to increase fuel efficiency in transportation, US EPA’s SmartWay program is a collaboration between the freight transportation industry and EPA that helps logistic companies, freight shippers, and carriers improve their fuel efficiency and save money [52]. Among other things, to achieve a target of reducing emissions of at least 40% by 2030, the EU has a ‘legislation on renewable energy, energy efficiency and governance of energy union and climate action’ [53].

4.2.3. The Carbon Tax System

In some places, the carbon tax is seen as a strategy toward Net Zero emission. However, it can be seen as a means to generate more revenue for the government. When industries have to pay the carbon tax, it becomes part of the expense. If the profit margin is kept constant, these expenses will be transferred to the consumers. Hence, the consumers are the ones paying carbon taxes. If the majority of the people do not have alternative sources of energy, there will be no choice other than to pay the carbon tax. If the financial model for the carbon tax system is one that allows the carbon tax to be transferred as additional business expenses to the customers, there may not be enough economic incentive on the part of various industries to invest in carbon capture systems. On the other hand, if the profit margin is fixed, and the carbon tax affects the profit margin, this could generate more economic motivation for positive action to explore cost-efficient carbon capture systems. Legislation that requires carbon capture technologies for all GHG emitting plants, in addition to special recognition through various certifications or a tax rebate program that covers a significant portion of (or all) the cost for the installation, operation, and maintenance of the carbon capture system, could encourage industries to explore carbon capture systems.

Some questions for the carbon tax system that may be considered in the jurisdiction where they are used include:

Will a company still have to pay carbon tax if they are able to implement reliable carbon capture technology?

What are the funds for carbon tax used for? Are these used to develop technologies to capture and reprocess carbon to more beneficial forms? Are these used to develop technologies that will eventually bring the people to a stage where there will be no more need for a carbon tax?

4.2.4. Opportunities Exist in the Reduction of Emissions through Ending Gas Flaring

Reliable technologies exist for gas flare capture. Methane is the largest component of natural gas [54]. Cars that are driven on natural gas emit significantly less carbon dioxide (CO₂), Nitrogen oxides (NO_x), and Sulphur (SO_x) per kilometer traveled than those that use petrol or diesel [55]. Meanwhile, methane is seen as one of the GHG emissions of concern. In this light, it can be said that there is a big concern in the world about compounds that have the potential to bring good benefits to humanity (if adequately tapped, processed, and used). In March 2019, approximately 20% of the 2.8 billion cubic feet of natural gas that is produced per day in North Dakota’s Bakken Shale is flared [34]. The world now has flare gas recovery systems. An organization [34] claims a long record of success in the conversion of flared gas into reliable, cost-effective power. The company advertises gas flare recovery systems for the oil and gas industry. On its website, the company advertises its ability to deliver customized solutions under a build, own, operate, and maintain contract (not CapEx). With that model, it is expected that there will be less concern about capital expenditure (CapEx) barriers for the project.

4.2.5. Reduction of GHG Emissions for Industrial Plants

Various industrial plants including power plants, refineries, etc., have huge emissions. Sometimes, a considerable portion of the emissions can be seen while driving by the plant. This raises a good research question in the effort to reduce global GHG emissions. Rather than releasing these emissions into the atmosphere in large quantities, can these emissions be captured and treated locally? Even though a considerable portion of the emissions from the exhaust of some industrial plants may be steam, the mode in which it is released into the atmosphere raises high concerns about environmental pollution. A further research question is ‘can the steam-like emissions that raise a concern of massive environmental pollution also be removed’? Figure 4 shows a view of a section of exhaust pipes from an industrial plant. Figure 5 shows a proposal for the localized capture and treatment of gaseous emissions. Figure 6 shows a comparison of the present state conditions with the proposed future state for emission management for industrial operations. It is obvious that the capture and treatment of gaseous emissions have not been a high priority in many industrial operations. This is one of the reasons there are big concerns about GHG emissions. Gaseous emissions management is a prospective industry that holds the potential to create several job opportunities in various communities. In addition to the potential for the creation of job opportunities, adequate gaseous emission management from industrial plants can open avenues for further conservation of natural resources. For example, captured methane can be used to provide heat and electricity to many homes. Section 4.2.6 describes some of the advantages of GHG emissions. In addition to helping to reduce the fears around GHG emissions, when this industry is adequately explored, various other beneficial compounds may be discovered from what is presently seen as gaseous waste.

4.2.6. Usefulness of some Components of GHG Emissions

Nitrous Oxide (N₂O)

Nitrous oxide N₂O is useful in the medical field [56]. For more than 100 years, Nitrous oxide has been used therapeutically as an anesthetic and analgesic substance [57]. Previous work on “a survey of the American academy of pediatric dentistry membership” indicated that a large percentage of practitioners reported that when other sedatives were combined with N₂O, they experienced compromised airways as a result of the patient being deeply sedated compared to when N₂O was used alone. This shows the usefulness of N₂O when used alone in sedation. However, a minority of the respondents reported that the office personnel complained or inquired about the ambient effects of N₂O. The most frequent concerns of the workers were related to the effects on reproduction, pregnancy, and miscarriage [56]. Nitrous oxide has also been used as a recreational drug. However, chronic abuse has caused harmful neurological effects and even death [57]. Although N₂O has found use in the medical field, the report shows that there is a need for more research on the most appropriate use for N₂O. Technologies to ensure the clean separation of GHG gases into useful components will go a long way in alleviating and turning the fears about GHG emissions into positive things such as plans on how to store and put these materials to good use.

Carbon Dioxide, (CO₂)

Approximately 230 Mt of CO₂ is used globally every year. The fertilizer industry uses approximately 130 Mt CO₂ in the manufacture of Urea, and approximately 70 to 80 Mt CO₂ is used in enhanced oil recovery. CO₂ is also used in fire suppression, the stimulation of plant growth in greenhouses, metal fabrication, food, and beverages. The transformation of CO₂ into fuels, chemicals, and building materials is the new pathway for using CO₂ [58]. Some scholars [59] reported that the use of CO₂ angiography in both diagnostic and interventional vascular radiology has been greatly expanded by recent advances in delivery systems, post-processing capabilities, and its extension to new vascular interventional procedures. In most parts of the arterial and venous circulations, CO₂ has been proven to be a safe and effective intravascular contrast agent. The study states that questions about neurotoxicity restrict the use of CO₂ arteriography to the abdomen, pelvis, and extremities. This also shows that although CO₂ has also found some good uses in the medical field, further research is needed to discover more ways to put CO₂ into good use. CO₂ has also found good use in concrete in terms of increased strength and improved set time [60,61].

Methane, (CH₄)

Methane is used primarily as a fuel for light and heat. It is also used in the manufacturing of organic chemicals [62]. A previous report [63] noted that, despite its multiple benefits, methane recovery is not widespread for several reasons. Some of these are, “historically, mining companies have not seen methane on its own as an energy resource”. It is a secondary by-product of the industrial process where it is emitted. Those that are responsible for methane emissions may not be familiar with the technologies for methane recovery, especially in developing countries. Poorly functioning energy markets and financially insolvent utilities and municipalities in many countries fail to provide the right atmosphere that will attract private sector investment in methane capture and utilization. Even in developed countries, gas flaring is yet to be stopped. Rather than leave this good resource to be of concern for many people, this study recommends that opportunities to capture, store, and distribute this good resource for more positive uses be explored.

At the present time, many industrial plants release gaseous substances into the atmosphere at high rates.

In the future, it is recommended that these gaseous emissions be captured through various appropriate means, which may include piping works to capture the gaseous emissions from the exhaust pipes, and directed to gaseous emission treatment stations, which may be located inside or close to the industrial plant. In situations where there is not enough space at or near the plant, the piping works may be extended further to where there is space for the treatment of the gaseous emissions. Where multiple exhaust pipes exist, multiple piping works can be performed to collect the gaseous emissions for further treatment.

Wherever applicable, storage tanks may be provided to store other materials that may be transported offsite for use or further treatment. In an effort to achieve better air quality for everyone, further research and concrete action are recommended for the transformation of the management of gaseous effluents from the state that we have today to a state where no one will see any gaseous effluents coming out of the exhaust pipes of industrial plants.

4.2.7. What Can We Have in the Localized Treatment Stations for the Gaseous Emissions?

Various potential GHG treatment methods have been described by different scholars. It is well known that condensation of water vapor transforms the vapor back into liquid water. Condensation is also an effective method of removal of some other volatile compounds. Volatile organic compounds are among the most common pollutants that are emitted from chemical process industries that deal with the manufacture and processing of chemicals such as solvents, liquid fuels, lubricants, degreasers, cleaners, and thinners [64]. The results of a model parametric study by some scholars [64] suggested that if there is a wide variation in the concentration of volatile organic compounds in the gaseous emissions, condensation followed by adsorption is an effective technique to control emissions. If VOC emission levels are high above 1%, condensation is found to be suitable, and if the VOC emissions are very low, adsorption is preferred for the removal of VOC. Another study [65] also noted that adsorption was effective if the concentration of VOCs is in parts per million levels, and the removal by cryogenic condensation is effective at a relatively higher concentration of VOC (>1%). With this information, a condensation section in one of the treatment plants should be beneficial in the localized treatment of some of the GHG emissions. Some researchers [66] described a method to remove sulfur oxides from flue gases. The proposed method includes the absorption of sulfur oxides in an aqueous alkali carbonate solution and the reduction and dissolution of the salts formed in water. The hydrogen sulfide that was obtained is processed into sulfur. The use of lime-coated sulfide pellets is a promising method for controlling sulfur oxide emission during the roasting of metal sulfides [67].

Unlike NO, which has low solubility, NO₂ is highly soluble in water [68]. Sulfur dioxide (SO₂) is soluble in water (11 g/l at 20 degrees C). Sulfur dioxide also dissolves in atmospheric moisture [69]. Some scholars [68] proposed a two-step process that is capable of removing NOx and SO₂ simultaneously. The proposal is made up of an ozoning chamber and an absorber that contains a reducing agent solution. The scholars reported that as exhaust gases pass through the ozoning chamber and absorber sequentially, a NOx removal efficiency of 95% was achieved and an SO₂ removal efficiency of 100% was achieved. Sodium sulfide was used as a reducing agent. The authors noted that H₂S formation from sodium sulfide can be suppressed through a reagent (NaOH). This information indicates that some of the GHGs are soluble in water. Some of the GHGs can also be absorbed by other solutions. One of the GHG capture and storage methods described by IPCC 2005 is ocean storage [39]. While that may not be a popular approach, it also confirms that some of the GHGs of concern can be locally contained through dissolution or absorption in some liquids. A previous study [5] noted that while the US power plants’ hourly reports have reliable data for CO₂ emissions, the hourly measurements for NO_x and SO₂ remain unreliable in some regions. Accurate measurements of the quantity of emissions will be helpful in planning for the efficient capture and reprocessing of gaseous emissions. If using the water-based solution to capture SO₂ and NO_x, knowledge of the rate of release of the gases and the quantity of the gases that can be dissolved by various amounts of solution will be helpful.

Some scholars [70] reported that the reaction of carbon dioxide with an aqueous solution of sodium hydroxide could result in the formation of sodium bicarbonate (NaHCO₃). An experiment in which a bench-scale unit of reactor systems was designed was able to capture 2 kg of CO₂ per day. While the absorption rate of CO₂ was more than 95%, the purity of the Sodium bicarbonate that was produced was more than 97%. The authors mentioned that the results from the experiment contain useful information for the construction and operation of a commercial-scale plant. The authors also noted that the possibility of carbon capture for coal power plants using sodium hydroxide could be confirmed through the experiment. Some other scholars [71] also performed an experiment on CO₂ capture via a NaOH solution, a membrane contactor, and an absorption column. It was reported that a gas stream that contains a 10–15% volume of CO₂ was treated in both a packed column and a membrane contactor setup. This leads to the capture of the contaminant using a sodium hydroxide solution to obtain a valuable product (sodium bicarbonate) that can be reused in the industry. The chemical reaction between CO₂ and alkaline-earth oxides and alkaline-like magnesium oxide (MgO) and calcium oxide (CaO) produce compounds such as magnesium carbonate (MgCO₃) and calcium carbonate (CaCO₃) commonly known as limestone. Those alkaline materials can be found in naturally occurring silicate rocks such as olivine and serpentine [39]. Some researchers [72] assessed “a novel energy efficient process (that potentially uses approximately half of the energy that is used in traditional causticization process using lime) for recovering sodium hydroxide from capturing CO₂ from ambient air”. In the effort towards achieving global emission targets, it is important that more effort be put towards capturing and reprocessing GHG emissions of concern (i.e., reprocessing of the emissions to beneficial substances for the ecosystem). For both energy sources, this study recommends further studies on how to best capture and reprocess emissions from the source. It will be beneficial to see research improvements that not only reduce GHG emissions but also convert them to other useful compounds for human use and for the ecosystem at large. This study recommends that the industrial gaseous outlets of the future will include gaseous emission treatment chambers to the extent that no emission will be seen entering the atmosphere. Given the beneficial uses of various GHG emissions of concern, a profitable industry can be developed from GHG emissions management.

4.2.8. Policy Implications of a Holistic Review of GHG Emissions for Both Electric and Fossil-Powered Vehicles

The identification of hotspots for GHG emissions requires that adequate action be taken to reduce the emissions. Various policies can be applied in an effort to reduce GHG emissions. However, these have different implications. Policy implications for emission reductions can be viewed from various angles including improved health, the need for equity and fairness, etc.

Policy Implications of Emission Reduction on Health

Household energy is closely related to clean air. It contributes to many health- and climate-relevant air pollutants and has a major impact on human health [73]. Hence, it is important to ensure that household energy is from a clean source. Battery-electric vehicles do not produce any tailpipe emissions, but emissions are produced from the combustion of fuels that are associated with the generation and distribution of electricity used to power these vehicles [74]. When charged at home, electric cars use part of household energy. If the electricity supply for the community is from a GHG-emitting grid, although there may be no tailpipe emission for the electric vehicles, the emissions from the electric grid can still be a health hazard for people that live in the community where the electricity is produced. Giving some contentions about the impact of GHG and climate change and citing various previous researchers that indicated that air pollution has adverse effects on human health, one scholar [37] mentioned that a consensus can be reached in the effort to care for the environment through a reduction in air pollution.

The Policy Implications of Emission Reduction Policy on Environmental Equity

Annual emission test for motor vehicles

Greenhouse gases and smog-forming pollutants are emitted from internal combustion engines [74]. A feasible option for emission management of all existing vehicles in the traffic stream could be to conduct an annual emission test to ensure that vehicles meet the minimum emission standards before they have their annual vehicle license renewed. The downside to this is an equity issue, as some may not be able to afford the cost of applicable upgrades to reduce emissions. Some communities have already included annual emission tests in the requirement for vehicle registration. A smog test for vehicles is required in some regions. In places where a smog test is required for registration renewal, a vehicle that fails a smog test will need to be taken for repairs to receive approval for registration renewal [75].

Emission Tax

Regarding emission fees, some scholars [76] suggested that a person who travels using a highly polluting vehicle should pay more than a person who travels using a clean car. The incentive for the person traveling in highly polluting vehicles is the reduction of emissions by improving vehicle emissions controls, replacing the vehicle with a cleaner one, or reducing travel. The incentive for manufacturers will be to develop cleaner cars that will result in cost savings for customers. Customers will have a monetary incentive to buy vehicles with low emissions [76].

Equity: Considerations for environmental equity should be an important part of any sustainable transport strategy [77]. In terms of equity, policies such as annual emission testing and marking vehicles that do not meet the emission standards as off-road vehicles may price out the poor on the road. Hence, while stringent emission standards may be enforced for newly produced vehicles, reasonable subsidies for the upgrade of vehicles that are already in the vehicle stream will be a good endeavor. Equity-based objectives and constraint has been incorporated into toll-setting models, especially as it relates to travel benefits and costs between different socioeconomic groups and geographic locations [78]. It will not be good to have people priced out of the road because they cannot afford upgrades for emission reduction systems. This challenge can be overcome through subsidies for people in various income brackets. Stringent policies may be made for vehicles that are to be manufactured. Tax on vehicle emissions will fall relatively heavily on poor households. When compared with the wealthy, poor vehicle owners drive vehicles that pollute more per mile, and they will spend more on miles as a proportion of their income [79].

The Policy Implications of Emission Reduction Policy on Socio-Economic Fairness for Various Municipalities

Fairness: Is it fair to ban a specific type of vehicle based on GHG emissions when all the vehicles have associated GHG emissions?

The above question is one that needs careful evaluation. Given that both electric vehicles and fossil fuel-powered vehicles have associated emissions when the electricity is from a GHG-emitting grid, a ban on one of the two types of vehicles based on emissions may not be justified if the associated (indirect) emissions from electric vehicles are not considerably lesser than the emissions from fossil-powered vehicles. A fair opportunity for the two vehicle types to determine which of the two can best achieve the lowest emissions from a holistic point of view, in the long run, will be ideal. Stringent emission guidelines/targets may be set for the two vehicle streams. Given specific emission reduction targets, a fair approach will be to give equal opportunity to the two vehicle streams and evaluate which one is able to achieve the specified targets/guidelines. Plug-in electric vehicles fall into two categories: Battery-electric vehicles (BEVs) and plug-in hybrid-electric vehicles (PHEVs) [80]. Plug-in hybrid offers flexibility for long-distance travel when a battery-electric vehicle may run out of charge before reaching the destination. It also allows for economic continuity for fossil fuel producers and municipalities that benefit from this. The economic impacts relate to various social factors including job security for many people in different places and economic stability for countries that rely majorly on the sale of fossil fuels. Job security and economic stability for a country can also be related to other social factors. If the GHG emissions from the electricity grid in a community are considerably lower than the overall GHG emissions for fossil-powered vehicles, when using a plug-in hybrid vehicle, people may be encouraged to ensure adequate charge for the vehicle to use more electric power for daily commutes.

Considering the heterogeneity in the consumption-based electricity mix and climate impact on fuel economy, some scholars [81] compared well-to-wheels greenhouse gas emission intensities of plug-in electric vehicles (PEV) and gasoline vehicles at the provincial level in 2017. The authors reported that due to GHG-intensive coal-based electricity and cold weather, the well-to-wheel GHG emission intensities for battery-electric vehicles and plug-in hybrid-electric vehicles (PHEVs) are higher than those from gasoline vehicles internal combustion vehicle engines in seven and ten northern provinces in China, respectively. The well-to-wheel GHG emission intensities of gasoline hybrid-electric vehicles and HEVs are lower in 18 and 26 provinces than those of BEVs and PHEVs, respectively. This indicates that the GHG emissions from the electric grid significantly affect the indirect emissions from electric vehicles. Some scholars [82] reported that GHG mitigation potentials of electric four-wheelers in India depend on where and when they are charged. Self-charging gasoline-electric hybrids can help achieve a 33% reduction in GHG emissions [82]. To maximize the impact of plug-in electric vehicles, a full set of policies is needed to address vehicle purchase and charging behavior [83]. Charging behavior can be a factor for consideration where the GHG emissions from the electricity grid vary with the time of day or with the season of the year. For example, if the electricity from the grid has to be supplemented with a more GHG-emitting source during peak load hours, then charging behavior may be of concern.

Designing subsidies for ‘cleaner vehicles’

Often, transportation planning decisions have significant equity impacts. Analysis of transportation equity is important, as more comprehensive equity analysis allows planners to better anticipate problems and incorporate equity objectives in planning. It can also help in maximizing equity objectives through optimized planning. Improved equity analysis in transport planning can help to reduce delays and conflicts and also better reflect a community’s needs and values [84]. Many policymakers want to make clean product subsidies more equitable [85]. The goal of many transportation policies is to increase the market share of clean vehicles [86]. In various places, a tax subsidy is one of the measures that is used to encourage the purchase of cleaner vehicles. The availability of electric vehicle models is increasing. However, most new electric vehicles are luxury vehicles and SUVs that cost more than early models [87]. This raises the issue of affordability, especially for low-income families. Subsidies for plug-ins will likely continue to play an important role in the transition from gasoline to electric passenger vehicles; however, to date, the purchase of most plug-ins falls with high-income households, raising concerns about the distributional consequences of the subsidies [85].

In addition to widespread availability, the cost to consumers is an important factor that will affect the widespread adoption of vehicles with alternative forms of energy. If a higher market share of vehicles with an alternative form of energy will be achieved, it is important to pay attention to the prices of these vehicles compared with other vehicles in the market. If the cost of vehicles with an alternative form of energy is significantly higher than traditional counterparts, the adoption of vehicles with an alternative form of energy will be low. If the cost of vehicles with an alternate form of energy is lower than the traditional counterpart, and if there is widespread and reliable infrastructure (such as fast charging stations) and low-cost and adequate maintenance services, then the adoption of these vehicles is likely to see a significant increase. Adequate intervention to ensure that the cost becomes more affordable will reduce the need for subsidies. It is also expected to boost market penetration. Some scholars [87] reported that equity is not incorporated into the incentives for electric vehicles. Among other equity issues, the charging infrastructure for electric vehicles is not equitably dispersed. In some cases, more incentives are given to higher-income buyers. More low-cost charging is suggested for lower-income residential areas [87]. A previous report [88] mentioned a scenario in which 70% of federal income tax credits for electric vehicles went to households that would have bought an electric vehicle without tax credits. The authors reported that the simulation of alternative subsidy showed that a subsidy design that provides more incentives to low-income households would have been less regressive and more cost-effective. Another researcher [85] reported that income-based subsidies are more equitable and more effective than uniform subsidies. Some scholars [89] explored the effectiveness of a real-world targeted subsidy policy. The authors reported success in a policy that was targeted to lower-income households (that are also living in districts that have poor local air quality) to replace older vehicles with newer and cleaner ones, i.e., a targeted subsidy policy to low-income households was successful in promoting the adoption of clean vehicles.

The design of subsidies for clean vehicles affects the purchase response. To improve the future policy of plug-in electric vehicles, it is important to understand the effectiveness and equity of existing policies, the environmental benefits that are realized, and how these benefits compare to costs [90]. The emission reduction from the adoption of new transportation technology is dependent on the emission reduction of the new technology relative to the ones that are being replaced [88]. A previous work [91] reported that higher subsidies for plug-in electric with bigger battery capacity result in higher adoption of battery-electric vehicles; however, higher plug-in hybrid-electric vehicle adoption is achieved when the policy for plug-ins does not discriminate between the two types of vehicles [91]. Subsidy design between different vehicle alternatives such as this can be based on reports on a justifiable analysis of needs for resource control, socio-economic factors, environmental impacts, and the need for energy security (diversification of energy). When designing subsidies for cleaner vehicles, if higher adoption would be achieved, it is important to ensure that such policies make cleaner vehicles affordable for low-income earners in society. In places where air pollution is primarily from the tailpipes of vehicles, if cleaner vehicles are only for the rich, the rich will not enjoy the benefits of clean air in the environment until cleaner vehicles are for everyone.

Sustainable energy for transportation

There is a growing interest in sustainability, sustainable transport, and sustainable development [92]. Sustainable development is that in which the needs of the present generation are met without compromising the ability of future generations to meet their own needs [93]. Hence, apart from the desire to control air pollution, the exploration of other forms of energy for transportation also allows for a reduction in the use of ‘non-renewable’ energy. In line with the principle of sustainability, this can help achieve responsible resource exploration in such a way that the resource will last for a longer time (i.e., many people in the future will still have access to the resources). Hence, the exploration of alternative energy for transportation is a good endeavor. However, it is important that this is performed in an equitable way. Equity (also called fairness or justice) refers to the distribution of benefits and costs (impacts) and their appropriateness [92]. In terms of sustainability, the concept of equity (fairness) can also be extended to fairness for future generations. Hence, it is important that we strive to use the resources in a way that future generations will have good access to the natural resources that they may need. Sustainable development strives to achieve an optimal balance between social, economic, and ecological objectives [92]. Hence, although based on environmental impacts alone, a total ban on vehicles that use fossil fuels may not be justified if the difference in emissions from the electricity grid in a community is not significantly lower than the emissions for fossil-powered vehicles (from a holistic review), in addition to social and economic factors, other factors such as sustainability (ensuring adequate resource availability for future generations) need to be considered in policies towards a gradual reduction in the reliance on fossil fuels and other non-renewable energy sources. This also applies to electricity generation, especially when the electricity is produced with non-renewable energy sources.

Opportunities in the improvement of fuel efficiency.

The competition of both electric and fossil-powered vehicles to determine which of the two options can help achieve less emissions is good for the global community. This report presented how to evaluate the emissions of the two options from a holistic viewpoint. The online tool for evaluating the fuel efficiency of various models of vehicles [41] shows a considerable variation in vehicle fuel efficiency. If fossil-powered vehicles can be improved to achieve high mileage with little fuel use, this will result in a great reduction of GHG emissions per distance traveled. Similarly, a considerable reduction or elimination of GHG emissions from the electricity grid will also result in lower emissions for electric vehicles. Given that improved fuel efficiency can translate to reduced GHG emissions, regulations/mandates to improve the fuel efficiency of fossil fuel-powered vehicles may also be a good approach to both reduce GHG emissions and ensure that natural resources can last longer for many generations. In addition, to increase the distance traveled per L of fuel, potential opportunities exist in the exploration of carbon capture/adsorption technologies for fossil-powered vehicles. As mentioned, the present design of fossil-powered vehicles puts them at a disadvantage to electric vehicles in terms of bringing various emissions of concern close to residential neighborhoods (through tailpipe emissions). The design for fossil-powered vehicles will need to be significantly improved to overcome this challenge (if they will be competitive with electric vehicles or with other vehicles that have no major emissions of concern). The producers of fossil fuels and fossil-powered vehicles may contribute more to funding research on the reduction of all emissions of concern. This may include carbon capture/adsorption for all fossil-fuel-powered equipment and vehicles. In terms of GHG emissions, as shown in the model, the vehicle of choice will be the one that has the lowest emissions. Some of the factors that can affect the choice between a hybrid-electric vehicle and a battery-electric vehicle are the driving distance that can be achieved with a full charge of the battery and the availability of adequate infrastructure for charging the vehicle along the route of travel. Certainly, no traveler will want to be stranded on a cold night along a highway because there is no nearby charging station for their battery-electric vehicle. Hence, policy implications for the choice of battery-electric vehicles should also include the construction of adequate charging stations in many places. This will include efforts to ensure that charging stations are within a reasonable distance from each other on all highways and within various municipalities. Further study is recommended on how various other social and economic factors may affect the choice between vehicles with different power sources in various municipalities.

The Policy Implication of the Effort to Reduce GHG Emissions through Improved Fuel Efficiency on Revenue for Road Maintenance

Another important policy implication when evaluating the improvement in fuel efficiency as a means of reducing GHG emissions is the revenue from fuel tax. Only a portion of the costs of motor vehicle use is covered by current fuel taxes. Fuel tax revenues have failed to keep up with rising construction costs and demand, as evidenced by vehicle miles traveled and other indicators once the vehicle fleet became more fuel efficient in the 1970s and 1980s [76]. If revenue from fuel tax forms a considerable portion of the budget for road maintenance, with an improvement in the fuel efficiency of vehicles, this revenue may be reduced to what it would have been if there is no improvement in the fuel efficiency of the vehicles on the traffic stream. Hence, adequate planning for an alternate pricing scheme for road maintenance will complement any move to improve fuel efficiency for vehicles in the traffic stream. This will also be a good thing to consider as the number of vehicles that are not billed for fuel tax increases in the traffic stream. Alternative pricing schemes include vehicle-miles-travel (VMT) pricing schemes in which vehicle owners can be billed for the amount of mileage traveled on a periodic billing system.

The need for efficient reduction in emissions from the grid

When evaluating the benefits of fuel savings, the wide variance in the carbon intensities of electricity is a major source of uncertainty [94]. As mentioned earlier, GHG emission from the electricity grid is not the same across the US and Canada. Some scholars [81] evaluated the well-to-wheel GHG emissions of gasoline and plug-in electric vehicles among provinces in China. The report indicated that the well-to-wheel GHG comparison for gasoline and plug-in electric vehicles varies among provinces. That result indicated that there are some variations in the GHG emissions from the electricity grid that were considered for their study. PHEV’s GHG emission reduction is dependent on the GHG emission from the electricity source. A researcher [95] performed an LCA of the GHG emissions of passenger cars in China, India, the USA, and Europe. Among other things, the scholar reported that in order to meet the Paris agreement goal, only hydrogen fuel cell electric and battery-electric vehicles have the potential to achieve the magnitude of life-cycle GHG emission reduction. It was reported that the life cycle emissions over the lifespan of battery-electric vehicles that are registered in Europe today are lower than comparable gasoline cars by 66–69%, 60–68% in the USA, 37–45% in China, and 19 to 34% in India. Meanwhile, some other researchers [96] presented a review and meta-analysis of electric vehicles. The result of their meta-analysis indicated that in a subset of countries across the European economic area, there is potential that electric vehicles could lead to greater life-cycle GHG emissions than a comparable diesel counterpart. Some scholars [97] mentioned that the benefits of grid-dependent electric vehicles can only be obtained under the condition that they are used in a low-carbon electricity grid. Given the planned decarbonization of the electric grid, electric vehicles can reduce transportation-related GHG emissions [98]. In the US, when compared to gasoline cars, a researcher [95] reported that PHEV has a 42–46% GHG emission reduction, a 25–27% emission reduction in Europe, and a 6–12% emission reduction in China.

4.3. The Need for Continuous Policy Improvement through Validated Reports from Continuous Research and Development Efforts

The concern that transitioning from fossil fuel to purely electric power for transportation will cause an economic shock to provinces and countries that rely majorly on the sale of fossil fuel calls for more research on how zero GHG emissions can be achieved from fossil-fuel-powered vehicles. A researcher [95] reported that there is no realistic pathway for the deep decarbonization of combustion engine vehicles. Meanwhile, some other scholars [98] reported that by mandating fuel economies or ethanol gasoline mixes, regulations can help achieve a reduction in the emissions from internal combustion engine vehicles (ICEVs) [98]. By recovering braking energy and storing it in a battery that can then be used to support propulsion with an electric motor, HEVs are reported to have approximately 20% less GHG emissions when compared to conventional gasoline cars [95]. This study recommends further research on how to increase the amount of electricity that is generated by HEVs. An increase in the energy generated for transportation with less fuel is expected to result in an overall reduction of GHG emissions. In the US, the state of California has the strictest emissions regulation. Categories of automobile emissions in California include super ultra-low emission vehicles, SULEVs (the emissions from these cars are 90% cleaner than an average new automobile); partial zero-emission vehicles, PZEVs (these vehicles have zero evaporative emissions and must meet the same emission standards as the super ultra-low emission vehicles); ultra-low emission vehicles, ULEVs (the emissions from these are 50% cleaner than an average new automobile); and zero-emission vehicles (these do not have tailpipe emissions; cars in this category include plug-in electric vehicles and hydrogen fuel cell vehicles) [99]. Previous work [100] presented results from the field-based measurement of multiple pollutant emissions from residential coal burning in a community in China. The scholars recommended that to reduce uncertainties in emission inventory estimation, more field measurements are necessary [100]. Given the reports of various improvements such as super ultra-low emission vehicles (SULEVs) that achieve at least 90% emission reduction than regular gasoline cars, as well as other fossil-fuel powered vehicles that are able to achieve significant GHG reductions, more field-based measurements are recommended to confirm the efficiency of the technologies that were applied to achieve the GHG emission reduction in those vehicles. After widespread verification of the efficiency of these vehicles, even after a certain number of years of operation, these technologies may be adopted as a minimum standard for fossil-fuel-operated vehicles.

Some scholars [98] noted that due to an increase in the fuel economy, future ICEVs may have emissions that are comparable to electric vehicles. Hence, both ICEV and EV can together lower the emissions from transportation at a faster pace. Another report [101] mentioned that a significant reduction in greenhouse gas emissions is possible if more efficient internal combustion engines continue to be part of the technology mix in the short term and more new energy vehicle penetration is achieved in the long term. Emission reductions from ICEV will require the specification of targets and adequate enforcement to ensure that the emission targets are met. The system dynamic model that is presented in this study can be helpful in conducting a holistic evaluation of GHG emission pathways to identify how each stage in the electricity production or fossil fuel production contributes to the overall GHG emissions in the transportation sector. This can be helpful in strategic planning on how to truly achieve zero GHG emissions in the transportation sector.

4.4. Caveats

The suggested localization and treatment of GHG from industrial plants is not something that is common at this time. However, previous research works that are cited show that this can be achieved. It will require various experiments to achieve the desired outcome. This will also require a great deal of cooperation from the applicable industries, political will, adequate funding for research and development, and willingness to achieve zero-emission from industrial plants. Over time, it is likely that there will be a buildup of black carbon in some pipes that are used to direct gaseous emissions to various treatment chambers. Periodic maintenance of these pipes may be needed to ensure that the system is cleaned and will be able to function optimally. It is recommended that these pipes (especially the interior portion) be made of non-corrosive materials. This is to help increase the lifespan of the system to minimize the impact of corrosion. This study recommends international recognition/awards for industries or countries that are first to showcase a localized gaseous emission treatment plant from their industrial plants. (i.e., all gaseous emissions from the industrial plant are captured and processed locally and no gaseous emissions can be seen from any exhaust pipe at the industrial facilities).

5. Conclusions and Recommendations

The effort towards emission reduction is commendable in the effort to achieve better air quality. Electric cars are often promoted as a more environmentally friendly mode of transportation when compared to fossil fuel-powered vehicles. Meanwhile, many electric-powered vehicles also need to obtain some power from the electricity grid for their operation. A considerable portion of the electric grid generates a sizeable amount of greenhouse gas while producing electricity. This study considered the GHG emissions from both electric vehicles and fossil-fuel-powered vehicles to evaluate potential opportunities for the improvement of the two designs. The result indicated that in terms of the associated GHG emissions from the electricity grid, electric vehicles are not always better than fossil-fuel-powered vehicles. The comparison of GHG emissions from a gasoline-powered pickup truck and an electric vehicle showed that in one out of eight regions, the gasoline-powered truck has slightly less tailpipe GHG emissions than the emissions that are associated with the electricity required to power a similar electric-powered truck for the same distance. The result is dependent on the type of energy that is used to generate the electricity (the emission per kWh used) and the energy use rate of the vehicle. Similarly, the emissions for fossil-fuel vehicles are dependent on the energy use rate of the fossil-fuel vehicle (fuel efficiency). This study further presented a system dynamic model to gain a big-picture view of the GHG impacts from transportation with two different energy sources. The GHG emissions can be reduced with the increased efficiency of technological innovations to reduce or eliminate GHG emissions. Other previous work has mentioned potential emissions from braking wear, tire wear, etc., which can come from both electric and non-electric vehicles. This area will require further study in the future. In terms of GHG emissions from electric and non-electric vehicles, the two sources have associated GHG emissions when using electricity from GHG-emitting power stations. However, there are opportunities for improvement through GHG emission-capturing technologies. Some areas for further research have been described in this study. Given the concern of gaseous pollutants with associated health hazards, this study recommends further research and implementation of GHG-capturing technologies from fossil-fuel-powered automobiles.

In addition, this study noted that a good portion of GHG emissions has the potential to bring good benefits to humanity at large if well developed. For example, the exploration of adequate technologies to capture and use methane in a beneficial way will help reduce the fears of the impact of methane as a GHG gas. This is also the case for Carbon dioxide, CO₂, and Nitrous oxide. The benefits of these gases have been mentioned in this article. The system dynamic model showed that as the efficiency of the GHG capture systems increase, the GHG released into the atmosphere will be reduced for power plants, fossil fuel extraction, and refinery operations. To reduce the fears around GHG emissions, this study recommends more effort be made in GHG emission capturing and reprocessing into beneficial forms at the point of release (from industrial plants).

Given the prospects that exist in the condensation of gaseous vapors, this study recommends the exploration of means to direct gaseous effluents from all industrial exhaust pipes to a gaseous effluent treatment chamber. The industries of the future should be ones in which no gaseous emissions will be seen from outside of the industrial plant. A schematic diagram for further research on this has been presented in this study.