13
Fuels and Trends
and India and gaining importance for transport vehicles. Natural gas occurs
as gas under pressure in rocks beneath the earth’s surface or more often in
solution with crude oil as the volatile fraction of petroleum is composed of
mainly methane with varying amounts of the paraffinic hydrocarbon family, ethane, propane, butane, (methane hydrate). Natural gas commercially
has been using as a fuel for centuries in China. However, for the past few
decades natural gas has been receiving more attention due to the increase in
price of petroleum products.
Natural gas reserves are evenly distributed on a global basis and therefore
provide better security of supply. Natural gas is being used in domestic
and industrial sectors. Natural gas essentially consists of methane (80–98%)
depending upon geographic origin and its properties are closer to that of
methane. Natural gas has been one of the most widely experimented fuels
proposed to replace liquid petroleum fuels. Research Octane Number (RON)
of CNG is approximately 130. The excellent antiknocking property of CNG
allows use of a higher compression ratio for increased power output and fuel
economy compared to petrol.
The CNG has an excellent lean flammability limit and has the potential
to reduce regulated and nonmethane hydrocarbon emissions compared to
conventionally fueled engines. Natural gas can be stored in gaseous form
at ambient temperatures and under high pressure (approx. 200 bar) as CNG
and in liquid form at cryogenic temperatures (–161ºC) and at atmosphere
pressure as liquefied natural gas (Nine et al. 1997).
1.4.3.2 Liquefied Petroleum Gas
Liquefied petroleum gas (LPG), a mixture of propane (C 3 H 8 ) and butane
(C 4 H 10 ) gas, is a popular fuel for internal combustion engines. It is a nonrenewable fossil fuel that is prepared in a liquid state under certain conditions.
This popularity comes from many features of the fuel such as its high octane
number for spark ignited engines, comparable to gasoline heating value that
ensures similar power output. The LPG is stored as a liquefied gas under
pressure at ambient temperature. The percentage composition of the mixture
depends upon the season, as a higher percentage of propane is kept in winter
and the same for butane in summer.
1.4.3.3 Hydrogen
Worldwide preparation to meet internationally enforceable greenhouse gas
emission limits from vehicles with the use of hydrogen in engines and fuel
cells may cause sustainable contribution to reduction in environmental pollution. Hydrogen is one of the clean fuels in the world, as it does not contain
carbon compounds. Hydrogen is a clean and efficient energy carrier with
the potential to replace liquid and gaseous fossil fuels. Significant work on
Fuels and Trends
and India and gaining importance for transport vehicles. Natural gas occurs
as gas under pressure in rocks beneath the earth’s surface or more often in
solution with crude oil as the volatile fraction of petroleum is composed of
mainly methane with varying amounts of the paraffinic hydrocarbon family, ethane, propane, butane, (methane hydrate). Natural gas commercially
has been using as a fuel for centuries in China. However, for the past few
decades natural gas has been receiving more attention due to the increase in
price of petroleum products.
Natural gas reserves are evenly distributed on a global basis and therefore
provide better security of supply. Natural gas is being used in domestic
and industrial sectors. Natural gas essentially consists of methane (80–98%)
depending upon geographic origin and its properties are closer to that of
methane. Natural gas has been one of the most widely experimented fuels
proposed to replace liquid petroleum fuels. Research Octane Number (RON)
of CNG is approximately 130. The excellent antiknocking property of CNG
allows use of a higher compression ratio for increased power output and fuel
economy compared to petrol.
The CNG has an excellent lean flammability limit and has the potential
to reduce regulated and nonmethane hydrocarbon emissions compared to
conventionally fueled engines. Natural gas can be stored in gaseous form
at ambient temperatures and under high pressure (approx. 200 bar) as CNG
and in liquid form at cryogenic temperatures (–161ºC) and at atmosphere
pressure as liquefied natural gas (Nine et al. 1997).
1.4.3.2 Liquefied Petroleum Gas
Liquefied petroleum gas (LPG), a mixture of propane (C 3 H 8 ) and butane
(C 4 H 10 ) gas, is a popular fuel for internal combustion engines. It is a nonrenewable fossil fuel that is prepared in a liquid state under certain conditions.
This popularity comes from many features of the fuel such as its high octane
number for spark ignited engines, comparable to gasoline heating value that
ensures similar power output. The LPG is stored as a liquefied gas under
pressure at ambient temperature. The percentage composition of the mixture
depends upon the season, as a higher percentage of propane is kept in winter
and the same for butane in summer.
1.4.3.3 Hydrogen
Worldwide preparation to meet internationally enforceable greenhouse gas
emission limits from vehicles with the use of hydrogen in engines and fuel
cells may cause sustainable contribution to reduction in environmental pollution. Hydrogen is one of the clean fuels in the world, as it does not contain
carbon compounds. Hydrogen is a clean and efficient energy carrier with
the potential to replace liquid and gaseous fossil fuels. Significant work on