82
Alternative Fuels for Transportation
4.1 Introduction
Diesel engines are widely preferred to gasoline engines for heavy-duty
applications in the agriculture, construction, industrial, and on-highway
transport sectors because of their higher thermal efficiency. However,
they are also known to be major sources of the emissions such as particulate matter (PM), soot, smoke, and nitrogen oxides (NO x ). On the other
hand, emission regulations in many countries have caused the research
on improving engine fuel economy and reducing exhaust emissions due
to increasing concern of environmental protection and fuel shortage.
Using alternative fuel is one of the most attractive methods to improve
fuel economy and to reduce environmental pollution. Among the alternative fuels, alcohols (such as methanol and ethanol), vegetable oils, animal
fats, biodiesel, and liquefied petroleum gas (LPG) are receiving interest
(Chao et al. 2001; Jothi, Nagarajan, and Renganarayanan 2007; Nwafor 2003;
Ozsezen, Canakci, and Sayin 2008; Sayin and Uslu 2008; Senthil et al. 2005).
These alternative fuels are largely environment-friendly, but they need to
be evaluated for their advantages and disadvantages if they were used in
engine applications. Despite its low cetane number and poor solubility in
diesel fuel, methanol is one of the attractive alternative fuels because it is
renewable and oxygenated. Practically, to reduce engine emissions without engine modification, adding oxygenated compounds to fuels seems to
be more attractive. Therefore, methanol may provide potential to reduce
emissions in diesel engines. This chapter reviews the potential, production methods, and fuel properties of methanol as well as its engine performance, combustion, and emissions.
4.2 Potential of Methanol
Alternative fuels can be derived from noncrude oil resources. Crude oils
are petroleum-based fuels. Among the popular alternative fuels are biodiesel, natural gas, propane, methanol, biodiesel, ethanol, and hydrogen (Zhu
1997). The use of alternative fuels in the future is inevitable with rising oil
prices and global warming being a dominant environmental issue. The leading goals for both energy security and the clean-air projects have increased
interest in the worldwide utilizations of alternative fuels in burners and
engines (Liao et al. 2006).
Methanol is the chemically simplest alcohol, containing one carbon atom
per molecule. It is a toxic, colorless, tasteless liquid with a very faint odor
and commonly known as “wood alcohol.” Because it is produced as a liquid, methanol is stored and handled like gasoline. In general, methanol
Alternative Fuels for Transportation
4.1 Introduction
Diesel engines are widely preferred to gasoline engines for heavy-duty
applications in the agriculture, construction, industrial, and on-highway
transport sectors because of their higher thermal efficiency. However,
they are also known to be major sources of the emissions such as particulate matter (PM), soot, smoke, and nitrogen oxides (NO x ). On the other
hand, emission regulations in many countries have caused the research
on improving engine fuel economy and reducing exhaust emissions due
to increasing concern of environmental protection and fuel shortage.
Using alternative fuel is one of the most attractive methods to improve
fuel economy and to reduce environmental pollution. Among the alternative fuels, alcohols (such as methanol and ethanol), vegetable oils, animal
fats, biodiesel, and liquefied petroleum gas (LPG) are receiving interest
(Chao et al. 2001; Jothi, Nagarajan, and Renganarayanan 2007; Nwafor 2003;
Ozsezen, Canakci, and Sayin 2008; Sayin and Uslu 2008; Senthil et al. 2005).
These alternative fuels are largely environment-friendly, but they need to
be evaluated for their advantages and disadvantages if they were used in
engine applications. Despite its low cetane number and poor solubility in
diesel fuel, methanol is one of the attractive alternative fuels because it is
renewable and oxygenated. Practically, to reduce engine emissions without engine modification, adding oxygenated compounds to fuels seems to
be more attractive. Therefore, methanol may provide potential to reduce
emissions in diesel engines. This chapter reviews the potential, production methods, and fuel properties of methanol as well as its engine performance, combustion, and emissions.
4.2 Potential of Methanol
Alternative fuels can be derived from noncrude oil resources. Crude oils
are petroleum-based fuels. Among the popular alternative fuels are biodiesel, natural gas, propane, methanol, biodiesel, ethanol, and hydrogen (Zhu
1997). The use of alternative fuels in the future is inevitable with rising oil
prices and global warming being a dominant environmental issue. The leading goals for both energy security and the clean-air projects have increased
interest in the worldwide utilizations of alternative fuels in burners and
engines (Liao et al. 2006).
Methanol is the chemically simplest alcohol, containing one carbon atom
per molecule. It is a toxic, colorless, tasteless liquid with a very faint odor
and commonly known as “wood alcohol.” Because it is produced as a liquid, methanol is stored and handled like gasoline. In general, methanol