Methanol
83
is currently made from natural gas, but it can also be made from a wide
range of renewable sources, such as wood, waste paper, coal, and biomass.
Methanol is a good candidate for alternative fuel investigations because of
its abundances, physical, and chemical properties (Hamid and Ali 2004;
Herz 2001).
As an alternative fuel, methanol is receiving more attention and has
become a potential application in both the transportation and the power
generation sectors (Hong et al. 2005). Methanol has the advantage of being
a liquid fuel that can be synthesized from gasification and reforming in
a variety of feedstocks like coal and natural gas using well-established
thermochemical technology. Methanol can also be produced from a wide
range of biomass including municipal and industrial waste. It can thereby
serve as a low carbon emitting fuel. Methanol can be an important option
for the replacement of gasoline (Bromberg and Cohn 2008). The main uses
of methanol as an alternative fuel are: direct use: blend with diesel or gasoline and indirect use: conversion of methanol to dimethyl ether, ingredient in production of biodiesel and hydrogen for use in fuel cell vehicles
(Herz 2001).
4.2.1 Methanol: gasoline Blends
Methanol may be used directly as an engine fuel just as LPG and ethanol.
The direct use of methanol as an engine fuel has advantages and disadvantages. The relative very high-latent heat of vaporization of methanol results
in a lower burning temperature in the engine cylinders as it does for ethanol.
The direct use of methanol as an engine fuel in passenger vehicles would
require nontrivial engine modifications and substantial changes in the lubrication system. Due to its high Reid Vapor Pressure (RVP) that is a measure of
affected volatility of blended gasoline, use of methanol as gasoline blending
is limited even though it has a high octane rating and is an excellent candidate of oxygenated hydrocarbons (Ingersoll 1996; Lee 1997; Lee Speight,
and Loyalka 2007). When pure methanol is used, cold start problems can
occur because it lacks the highly volatile compounds (butane, iso-butane,
propane) that provide ignitable vapor to the engine even under the most
frigid conditions. The addition of more volatile components to methanol is
usually the preferred solution (Cheng and Kung 1994; Olah, Goeppert, and
Prakash 2006).
4.2.2 Methanol: Diesel Blends
Methanol and diesel are not very miscible, which makes it difficult to
mix the PM together as a diesel engine fuel. Methanol–diesel blends gave
good performance when the amount of methanol in the mixed fuel does
not exceed 30% by weight (Shi et al. 1983) and combustion characteristics
when the maximum methanol mass fraction was 20% by weight (Huang
83
is currently made from natural gas, but it can also be made from a wide
range of renewable sources, such as wood, waste paper, coal, and biomass.
Methanol is a good candidate for alternative fuel investigations because of
its abundances, physical, and chemical properties (Hamid and Ali 2004;
Herz 2001).
As an alternative fuel, methanol is receiving more attention and has
become a potential application in both the transportation and the power
generation sectors (Hong et al. 2005). Methanol has the advantage of being
a liquid fuel that can be synthesized from gasification and reforming in
a variety of feedstocks like coal and natural gas using well-established
thermochemical technology. Methanol can also be produced from a wide
range of biomass including municipal and industrial waste. It can thereby
serve as a low carbon emitting fuel. Methanol can be an important option
for the replacement of gasoline (Bromberg and Cohn 2008). The main uses
of methanol as an alternative fuel are: direct use: blend with diesel or gasoline and indirect use: conversion of methanol to dimethyl ether, ingredient in production of biodiesel and hydrogen for use in fuel cell vehicles
(Herz 2001).
4.2.1 Methanol: gasoline Blends
Methanol may be used directly as an engine fuel just as LPG and ethanol.
The direct use of methanol as an engine fuel has advantages and disadvantages. The relative very high-latent heat of vaporization of methanol results
in a lower burning temperature in the engine cylinders as it does for ethanol.
The direct use of methanol as an engine fuel in passenger vehicles would
require nontrivial engine modifications and substantial changes in the lubrication system. Due to its high Reid Vapor Pressure (RVP) that is a measure of
affected volatility of blended gasoline, use of methanol as gasoline blending
is limited even though it has a high octane rating and is an excellent candidate of oxygenated hydrocarbons (Ingersoll 1996; Lee 1997; Lee Speight,
and Loyalka 2007). When pure methanol is used, cold start problems can
occur because it lacks the highly volatile compounds (butane, iso-butane,
propane) that provide ignitable vapor to the engine even under the most
frigid conditions. The addition of more volatile components to methanol is
usually the preferred solution (Cheng and Kung 1994; Olah, Goeppert, and
Prakash 2006).
4.2.2 Methanol: Diesel Blends
Methanol and diesel are not very miscible, which makes it difficult to
mix the PM together as a diesel engine fuel. Methanol–diesel blends gave
good performance when the amount of methanol in the mixed fuel does
not exceed 30% by weight (Shi et al. 1983) and combustion characteristics
when the maximum methanol mass fraction was 20% by weight (Huang