Sustainable Air Pollution Management in Transportation Sector
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Transportation sector has transformed dramatically over the years. Here as the demand for vehicles has reached saturation level in developed countries, other countries have become market heavens for vehicle manufacturers. Land, air and water transportation has increased many folds for shifting both passengers and cargo from one place to other. This chapter discuss major issues and solution with respect to transportation which includes shifting to green fuel, improving mass transportation, ensuring good quality fuel, eco friendly engines and fuel, vehicular emission standard.
KeywordsElectric Vehicle Selective Catalytic Reduction International Civil Aviation Organization Heavy Duty Vehicle Sustainable Transport
Locomotion is key characteristic of humans. Humans travel across the globe in variety of vehicles. Apart from fuel combustion, air pollution is also caused due to re-suspension of soil particles in case of road transport and for some extent in takeoff/landing operations in aviation operation.
People travel for many purpose that include (1) tourism and recreation, (2) education, (3) exploration, (4) job, (5) movement of goods, (6) to avail service, (7) to meet people, (8) rescue operation during emergency, (9) to perform crime, and (10) the investigate/interrogate/arrest criminals. The major reasons that influence transport trends are travel time budgets, costs, increased personal income, as well as social/cultural factors (Schäfer 2011).
About 10 % of the worldwide population account for 80 % of motorized passenger-kilometres (p-km) with OECD nations dominating GHG transport emissions even though most recent growth has taken place in Asia (Sims et al. 2014)
Use of electrically driven vehicles;
Use of fuel cells and battery driven electric vehicles;
Use of eco friendly fuel like natural gas and hydrogen;
Increasing fuel efficiency;
Changing to less carbon-intensive fuel;
Reducing emissions from vehicle exhausts;
Reducing weight of vehicles;
Intelligent traffic management to avoid unnecessary traffic jams and to many signals; and
Restriction of private vehicle ownership.
All the solutions may not be acceptable to all the people. Rich people who travel for fun may recommend fuel efficiency instead of stopping travelling. All public will not avail public transport even when it is available. Many public transport vehicles in developing countries are overcrowded resulting in suffocation. These vehicles are also known for frequent pickpockets. The public transportation in some cities are characterized by lack of adherence to schedule, sexual harassment, impolite staff, inefficient/infrequent service, non availability of service during night as well as riots (Chandrappa et al. 2011).
Transportation sector represents around one-quarter of energy consumption worldwide (Clark and Kelly 2004). Over 53 % of world wide primary oil consumption in 2010 was used to satisfy 94 % of the total transport energy demand, with natural gas and other fuels 3 %, biofuels contributing approximately 2 % and electricity 1 % (IEA 2012). The transport sector is predominantly fueled by petroleum products. This huge demand puts a large stress on global reserves, and results in environmental degradation. The efficiency can be increased by: (1) improving engine/vehicle designs; (2) increasing the load factor; (3) ensuring traffic/usage patterns are optimal (by adopting practices like efficient routing, and avoiding empty back hauls); (4) switching over from less to more efficient transportation modes; (5) reducing the need for transport; and (6) changing over to eco friendly fuels.
Sustainable transport refers to an acceptable level of social cost associated with the movement of goods or people. Transport plays an important role in a country’s environmental performance and the sustainability of its development. Mobility and infrastructure have many effects on the ecological system and the spatial organization of economic activities. The demand for transport leads to a large pressure on the sustainability of the living environment. Technological development is often seen as one of the ways to increase sustainability of transport. Despite potential, there are some barriers to technological implementation that hinder short-term viability. Policy intervention can also steer transport development toward sustainability. A wide range of measures are available to policy makers, ranging from transport demand measures to spatial planning interventions.
Sustainable transport is a distant reality in many countries where transportation itself is a luxury. Sustainable transportation means transportation at an acceptable level of social cost connected with the movement of people or goods. Social costs include impact on environmental quality, injury/fatality.
Transport which is wheel of economy is also responsible for injury/death, resource depletion, air/noise pollution, source of some of the hazardous waste, and threat to biodiversity. While road/railways affect terrestrial ecosystem sea/inland waterway pollute ecologically sensitive coastal waters. Pollution form motor vehicles generates around one-fifth of the incremental CO2 in the atmosphere (Nijkamp et al. 2003).
Transport sector degrades environment during creation of infrastructure and later by its use. The roads and railways are often causing for fragmentation of terrestrial ecosystem.
Alternative vehicle fuel include CNG, hybrid-electric, LPG, ethanol and methanol. Ethanol is produced from grains or sugar. Electric vehicles (EV) use an electric energy. The mode of electric generation decides sustainability and quantum of air pollutants released into atmosphere. Solar, hydel, hydro, wind energy generation promises good air quality compared to energy generated from thermal power plants.
Hybrid electric vehicles comprise of the electric motor that can be powered either by a battery or fuel. These vehicles provide environmental benefits over conventional vehicles.
Vehicles powered by fuel cells combine hydrogen and oxygen to produce the electricity. The emissions from fuel cell vehicles depends on the primary fuel used, as well as where the fuel is reformed that is whether hydrogen is produced from solar, wind, thermal or hydropower. Battery-electric vehicles include two wheelers, three wheelers, cars, buses and trains. The primary advantages of such vehicles are that there will be zero emission at the path of their use.
Synthetic fuels include bio-diesels, Fischer-Tröpsch diesel, as well as di-methyl ether (DME). Bio-diesel can be manufactured from vegetable oils. Diesel fuel synthetically produced from coal or natural gas or through a process called Fischer-Tröpsch is known as Fischer-Tröpsch diesel. DME is a synthetic fuel produced from methanol or renewable raw materials or, natural gas.
6.1 Air Transport
Increase in aviation activities both military and civil aviation contribute to air pollution. The emission from aviation activity would contribute to climate change through emissions CO2, VOC, NOx, water vapor, SO2, soot and other particles to environment (Brasseur et al. 1996). A large fraction of these emissions occurs at roughly 9–11 km from surface of earth. Hence, many studies have concentrated on the resulting climate change of aviation emissions in the lower stratosphere and upper troposphere (Brasseur et al. 1998; Hendricks et al. 2000; Morris et al. 2003).
Piston aircraft Engines use similar fuels and have the same characteristics as gasoline(petrol)-powered automobile engines. The sources as well as pollutants are hence similar to emission from motor vehicles (John 1977). Gas turbine engine (jet) emissions as well as fuel are similar to diesel engines.
Emissions from aircraft gas turbine engines differ from that of motor vehicles with respect to “fuel-venting emission.” Every time a turbine engine is shut down or started up, some fuel previously present in the system is drained to a dump. Normally dumping fuel is carried out after takeoff (John 1977).
Emissions from aircraft occur on the ground during idle, start-up, taxi, and shut-down operations. Emissions also occur from engine during repair.
Aircraft engines usually combust fuel efficiently, and exhausts from jet have very less smoke emissions. Pollutant emissions in and around airports are more due to aircraft movements, surface traffic and airport operations. Particular emission from jet will be mostly in P2.5 fraction. The International Civil Aviation Organization (ICAO) has set international standards for emission from aircrafts. It also restricts the venting of fuels from aircrafts. Technologies such as selective catalytic reduction as well as exhaust gas recirculation have been employed in aircrafts to reduce air pollution.
Emission from landing and take-off (LTO) emissions will have less impact than non-LTO due to relatively large quantity of non-LTO emissions (Lee et al. 2013). As per studies by Barrett et al. (2010) non-LTO aviation emissions may adversely affect local air quality particularly with respect to particulate matter. Barrett et al. (2010) concluded that secondary aerosols like sulfate-ammonium-nitrate formed by SOx and NOx emissions from aircraft can be increase premature deaths worldwide.
An understanding of contributions of NOx (NO and NO2) and total reactive nitrogen NOy(NO) distribution is essential because NOy emitted into the upper troposphere is longer-lived compared to odd nitrogen emitted into the boundary layer. Also NOy is responsible for producing more O3 (Lee et al. 1987; Hauglustaine et al. 1994).
Emissions during landing as well as take-off are responsible for most of the NOy, ozone (O3) and aerosol perturbations near the ground. Aviation-induced perturbations have an insignificant effect on air quality (Lee et al. 2013).
In-flight operations cover climb-out to about 914 m above ground and descend from 914 m to ground. The 914 m elevation is assumed to be the top of the temperature inversion below which atmosphere dispersion would be poor. Pollutants below this level would most likely affect the community near the airport, whereas above 914 m the pollutants are dispersed more thoroughly (John 1977).
6.2 Water Transport
Replacing smaller vessels by larger vessels with better shipping energy;
Selective catalytic reduction (SCR);
Direct water injection (DWI);
Humid air Motors(HAM); and
In SCR urea/water solution is injected into exhaust stream over a catalyst to reduce nitrogen oxides to nitrogen gas. In DWI, fresh water is mixed with the fuel and injected with high pressure into the combustion chamber. The water vapour reduces the combustion temperature reducing formation of nitrogen oxides. In HAM, sea water is vaporised by waste heat from the engine’s cooling system as well as turbo-chargers and mixed prior to the combustion chamber reducing combustion temperature thereby reducing the nitrogen oxides. Sulphur reduction in emissions from shipping is achieved by using low sulfur fuel and installing scrubber (Swedish Maritime Administration 2007).
Apart from above technology the sector in developed countries is active in emission trading to bring down overall emission at global level from the sector.
The International Convention for the Prevention of Pollution from Ships [MARPOL (short from for Marine Pollution)] is the most important international convention for prevention of marine pollution by ships. MARPOL has been updated by amendments over the years. It was adopted on 2 November 1973 at IMO. It covers pollution by oil, harmful substances in packaged form, chemicals, sewage and garbage.
- Annex I:
Regulations for the Prevention of Pollution by Oil
- Annex II:
Regulations for the Control of Pollution by Noxious Liquid Substances in Bulk
- Annex III:
Prevention of Pollution by Harmful Substances Carried by Sea in Packaged Form
- Annex IV:
Prevention of Pollution by Sewage from Ships
- Annex V:
Prevention of Pollution by Garbage from Ships
- Annex VI:
Prevention of Air Pollution from Ships
Annex VI of MARPOL was entered into force 19th May 2005 and it was ratified by 75 States/Parties. This annex set limits on PM, NOx and SOx emissions from ship exhausts. This annex prohibit deliberate emissions of ODS.
6.3 Land Transport
- Motor vehicle restraints
Selective vehicle entry permits
Ban of heavy duty vehicles
Restriction on delivery times
Regulation of office/business timings
Regulation of school timings
Encourage non motorised transport (animal driven, bicycle, walking, push/pull cart)
- Control of fuel
Increasing cost of fuels
Ensure zero fuel adulteration
Reduce sulfur content from fuel
Sell un-lead fuel
- Motor vehicle emission reduction
Inspection and maintenance
Gasoline(petrol) vapor control
Changing or improving technology
- Improvement of mass transportation
Bus lanes on city streets as well freeways
One way streets to buses only
Reducing cost of public transportation
Improving service of pubic transportation
Road user tax
Banning old vehicles
- Voluntary approaches
Use of video conferencing rather than physical meeting
Car-pooling and ride-sharing
- Traffic flow improvements
One way street operation
Approaches to reduce the emissions from land transport can be theoretically achieved by intervening with the vehicles and the fuels (Gorham 2002). But in practice the narrow roads/streets with high rise building on both sides of roads/streets still exists posing hindrance to movement of air pollutants.
6.3.1 Shifting to Green Fuel
Confronted with rising oil prices, and to protect environment biofuel production has been encouraged in many parts of the globe. Agricultural food produce has been used to manufacture “green” fuels apart from nonagricultural sources. Some of the bio fuels are ethanol, biodiesel, methanol, biobutanol. In many countries 10–15 % ethanol is normally added to gasoline(petrol). Major factors considered in use of biodiesel are cost, availability, as well as food supply.
6.3.2 Improving Mass Transportation
Movement of people and goods in bulk plays an important role in a country’s economic and environmental performance. Sustainable transport is a perception that refers to a satisfactory level of social cost connected with the movement of goods and people. These social costs include degradation of environmental quality, fatality due to accidents, or traffic congestion.
Public transportation system includes buses, light rail, rapid transit system, tram, personal rapid transit.
Rapid transit is a high-capacity public transport in urban areas. Rapid transit systems operate on an exclusive right-of-way. It helps to transport large numbers of people swiftly over short distances with minute use of land. Variations of rapid transit include people movers, small-scale light metro, as well as the commuter rail hybrid.
Personal rapid transit (PRT), which is also called podcar, employs small automated vehicles operating on a network of built guide ways. PRT typically carries not more than 3–6 passengers per vehicle.
Inappropriately designed transport systems will damage the environment. More than half a million people die every year due to road accidents (Nijkamp et al. 2003).
6.3.3 Ensuring Good Quality Fuel
Fuel options can be targeted to non-achievement regions/seasons.
Fuel refining as well as distribution is highly centralized, therefore modifications are easy to negotiate as well as enforce.
Fuel modifications may require low investment than modification of engine and can be applied to a larger range of engines.
6.3.4 Eco Friendly Engines and Fuel
Transport and economic development are linked. Transportation essentially enables and catalyses development. Demand for passenger as well as freight transport in developing countries will increase rapidly in coming decades. Developing countries need to avoid the ‘lock-in’ of unsustainable transport that accompanied growth of economy in developed countries.
The most graceful invention that ever had a larger impact on the economy, society, as well as the environment is the reciprocating IC engines (Haworth and El 1998; John 1988). At present there is a need to develop sophisticated combustion engines that make best use of the engine efficiency and totally lessen the exhaust emissions (Kumar and Kumar 2011). IC engines generate work using the combustion products as the working fluid. Combustion is carried out in a way that produces high-pressure burning products that are expanded through a turbine/piston. These high pressure systems introduce a numerous features that influence the pollutant formation.
In recent years the scientific as well as public awareness on environmental/energy issues has brought in significant interests to invent efficient IC engines. As the energy consumption is proportional to the economic development, global energy demand is likely to rise in future. The motorised movement of goods and people increased more than a 100 fold over the 20th century while the human population increased by four fold (UNEP 1999; AAMA 1998). In 2008, more than 50 % of the world’s population lived in urban region (Dalkmann and Huizenga 2014) and by 2050 it is expected that ¾ of global population will live in urban areas (IEA 2008). The process of urbanisation has resulted in more vehicles and air pollutants. Collectively cities are expected to account for 71 % of global GHG emissions and 67 % of worldwide energy related CO2 emissions (Dalkmann and Huizenga 2014). Such scenario attracts need for sustainable transport that allows the basic access and needs of citizens safely, cheaply and with least impact on environment.
6.3.5 Vehicular Emission Standard
Vehicular emission standards vary worldwide and over a period of time. The prominent among the emission standards are European Emission Standards which is adopted with slight or no modification by different countries.
European emission standards stipulate the acceptable limits for emissions from vehicle exhaust of new vehicles sold in European Union (EU) member states. These standards are defined in a number of European Union directives. These standards aim progressive introduction of progressively more stringent standards.
Currently, emissions of NOx, total hydrocarbon (THC), NMHC, CO and PM are regulated for most vehicle types excluding seagoing ships as well as aeroplanes. Different standards apply for different vehicle type. Vehicles that do not comply with EU emission standards cannot be sold in the EU, but these new standards are not applicable to vehicles already on the roads. Compliance is determined by operating the engine at a standardised test cycle. No use of specific technologies is compelled to meet the standards.
The stages of EU emission standards are typically referred to as Euro 1, Euro 2, Euro 3, Euro 4 and Euro 5 for Light Duty Vehicle standards and the standards are refereed as Euro I, Euro II, EURO III etc., for Heavy Duty Vehicles (Roman numbers are used rather than Arabic numerals for Heavy Duty Vehicles).
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