barrels in 2015 and 118 million barrels in 2030 [4]. By using the Hubbert peak
theory [5–7], the oil depletion situation can be predicted based on prior discovery
rates and anticipated production rates. The American Petroleum Institute estimated
in 1999 that the world’s oil supply would be depleted between 2062 and 2094 [8].
Oil depletion curves are depicted in Fig. 1.1. The oil shortage will result in severe
social and economic problems such as transportation and food crisis.
ICE powered vehicles rely on gasoline and diesel combustion during operation.
Pollutions are generated during the combustion process inside the ICE. In addition,
unburned fuel evaporates which forms the basis for another type of pollution-
volatile organic compounds (VOC).
The emissions from the combustion include carbon dioxide, VOC, nitrogen
oxides (NO
x
), particulate matter (PM), and carbon monoxide (CO). These exhaust
emissions occur during the following two modes [10, 11]:
• Cold Start—during cold weather, the catalyst which is used to control tailpipe
emissions will not work until they have been warmed up to a certain temper-
ature. Hence, starting and driving a vehicle in the first few minutes result in
higher emissions.
• Running Exhaust Emissions—emissions are formed during normal operation of
the vehicle-driving and idling.
Through the fuel evaporation, the VOC leaves for the ambient air, which occurs
in four ways as follows:
• Running Losses—During vehicle running, the gasoline is vaporized in the hot
engine and exhaust system.
• Hot Soak—The engine remains hot for a while after the vehicle is turned off,
and gasoline evaporation continues when the car is parked while cooling down.
• Diurnal Emissions—Even when the vehicle is parked for long periods of time,
gasoline evaporation occurs due to the high ambient temperature.
• Refueling—While the tank is being filled, gasoline vapors escape from the
vehicle’s fuel tank and the refueling tubes.
In the United States, vehicles contribute 25 and 33% of the total VOC and NO
X
respectively which combine to form ground-level ozone. Additionally, the
combined direct and indirect contribution of vehicles amounted to 49 and 55% of
national PM
10
and PM
2.5
(both belong to particulate matter) emissions, respec-
tively [12]. Unfortunately, ozone and particulate matter are identified as contrib-
utors towards worsening the health of people with asthma and other related public
health impacts, e.g. increases in medication use, doctor and emergency room (ER)
visits, and hospital admissions. Moreover, the possible contribution of vehicle
pollution to the development of asthma, frequent respiratory infections and
potential long-term effects of retarded lung growth and reduced lung function in
children (which can lead to chronic lung disease later in life) may even have
greater long-term public health significance [13].
Besides, vehicles play a disgraceful role in global climate change. Burning of
fossil fuels contributes to the increase of carbon dioxide (CO
2
) in the atmosphere.
2 1 Introduction