Page 249 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Engine systems 233

Figure 2.308 Biodiesel engine

non-toxic
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safer to handle.
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Disadvantages:
use of blends above B5 may not yet be approved by manufacturers
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lower fuel economy and power (10% lower for B100, 2% for B20)
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more NO x emissions
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B100 generally not suitable for use in low temperatures
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concerns about B100’s impact on engine durability.
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2.5.4.3 Natural gas
Natural gas is a fossil fuel made up mostly of methane. It is one of the cleanest
burning alternative fuels. It can be used in the form of compressed natural gas Key fact
(CNG) or liquefi ed natural gas (LNG) to fuel cars and trucks. Dedicated natural Natural gas is a fossil fuel made up
gas vehicles are designed to run on natural gas only, while dual-fuel or bi-fuel mostly of methane.
vehicles can also run on petrol (gasoline) or diesel ( Fig. 2.309 ). Dual-fuel vehicles
take advantage of the widespread availability of conventional fuels but use a
cleaner, more economical alternative when natural gas is available. Natural gas
is stored in high-pressure fuel tanks so dual-fuel vehicles require two separate
fuelling systems, which take up extra space. Natural gas vehicles are not
produced commercially in large numbers. However, conventional vehicles can be
retrofi tted for CNG.
Advantages:
60–90% less smog-producing pollutants
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30–40% less greenhouse gas emissions
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less expensive than petroleum fuels.
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Disadvantages:
limited vehicle availability
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less readily available
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fewer miles on a tank of fuel.
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