Unleaded petrol: Safer than leaded?<\/p>\n
By Kardono<\/p>\n
JAKARTA (JP): Lead gasoline car emission is now widely
\ndebated. It has been linked to health disorders such as
\nneurological damage and heart disease in adults and learning
\ndisabilities and decreased IQs in children.<\/p>\n
The state-owned Pertamina oil company launched unleaded
\ngasoline in August 1995. It was entitled BTT (Bahan Bakar Tanpa
\nTimah). The government plans to use this to gradually phase out
\nlead gasoline.<\/p>\n
The World Bank has urged all nations to phase out lead
\ngasoline because of related health problems.<\/p>\n
Studies in the U.S. by Caio Koch-Weser (a World Bank
\nrepresentative) have suggested that for every dollar invested in
\nunleaded gasoline a community will save ten dollars in health and
\nother costs.<\/p>\n
The cheapest and most efficient way to make unleaded gasoline
\nis to add tetra ethyl lead (TEL) to gasoline. This process raises
\nthe price of unleaded gasoline. The market price of normal
\ngasoline is Rp 700 (US$ 0.3) compared to around US$ 0.4 for
\nunleaded.<\/p>\n
Adding lead alkali anti-knock compounds to gasoline
\nincreases octane quality (RON). RON or research octane number is
\nan international measure of gasoline quality. A higher number
\nmeans higher octane quality - RON numbers for gasoline generally
\nfall between 80 and 98.<\/p>\n
Typically, a car designed to run on 98 RON gasoline will have
\na 10 to 15 percent better fuel economy than one designed to run
\non 90 RON fuel.<\/p>\n
Many older cars cannot use unleaded fuel. Leaded gasoline
\nlubricates an engine's exhaust valve seats. Older cars have
\nengines with cast-iron cylinder heads with `soft' valve seats. If
\nthese cars use unleaded fuel, the valves may recess into their
\nseats which causes engine damage.<\/p>\n
Most modern cars are fitted with catalytic converters which
\nstop this problem occurring.<\/p>\n
Fuel additives, made of sodium, potassium and phosphorus,
\nhelp older cars use unleaded fuel, but they are not as effective
\nas leaded fuel, especially when engines are under stress. On the
\nother hand, unleaded fuel containing these additives cannot be
\nused in modern catalyst engines.<\/p>\n
When reducing or eliminating lead in gasoline, refineries
\nmust add certain components to maintain octane quality. These
\ncomponents include benzene, toluene, xylenes and ethyl benzene.<\/p>\n
Also to enhance octane quality, a refinery is likely to use an
\naromatic or oxygenates such as ethers, methanol or ethanol.<\/p>\n
These components, added in 5 to 15 percent concentration, are
\nnot cost-effective and may cause technical and environmental
\nproblems.<\/p>\n
There is no doubt that high lead levels are dangerous. Lead
\ncan affect the central nervous system and cause hypertension,
\nincreased coronary heart disease, cardiovascular disease and
\ndamage brain development in children. Lead can also cause
\ndeposits in engines and exhaust systems.<\/p>\n
Unleaded fuel has been promoted as a replacement to leaded
\nfuel but there are environmental problems associated with
\nunleaded fuel which may be more dangerous.<\/p>\n
It is well known that aromatic hydrocarbons in gasoline are
\ncarcinogenic, with benzene being the most potent. Increased
\nexposure to benzene in gasoline is reported to contribute to
\nincreased incidence of leukemia. Unleaded fuel requires greater
\nuse of aromatics.<\/p>\n
Increased aromatics also increase ozone levels. The aromatic
\nand olefinic components of gasoline produce photochemically
\nreactive exhaust emissions. That is, they will create ozone.<\/p>\n
The aromatic, olefins and oxygenates in unleaded gasoline
\nproduce health and environmental dangers greater than lead when
\nunleaded fuel is used in cars not fitted with catalysts. The
\ncarcinogenic component of such emissions is benzene. Leukemia and
\nlung cancer are caused by monoaromatic compounds in emissions
\nincluding toluene and xylenes, polyaromatic hydrocarbons (PAHs),
\nformaldehyde and other aldehydes.<\/p>\n
Gasoline containing elevated levels of aromatics also have a
\nhigher calorific value. Such fuels have been shown to produce
\ngreater amounts of nitrogen oxides in car emissions.<\/p>\n
Good catalysts fitted to well maintained cars are likely to
\nsignificantly reduce hazardous emissions. But a question mark
\nremains over the durability of catalysts, especially three-way
\ncatalysts. We must also see to regular inspection and maintenance
\nof catalyst-equipped cars.<\/p>\n
Three-way catalysts, which control hydrocarbon, CO and NOx
\nexhaust emissions, necessitates electronic fuel injection, either
\nmultipoint or throttle body, to ensure correct fuel metering.<\/p>\n
This is required to maintain an air-fuel ratio which is at or
\nnear a stoichiometric (14.7:1) point so that the catalyst can
\nsimultaneously convert HC, CO and NOx into harmless products.<\/p>\n
It is widely recognized that, even in a new car, deposits will
\nbuild-up on the inlet valves of fuel injectors and in the
\ncombustion chamber which can lead to more exhaust emissions.<\/p>\n
Deposits formed in these sensitive areas are largely due to
\nolefins and aromatics in fuel which polymerize and decompose into
\ncarbonaceous products.<\/p>\n
Clearly, reducing risks from leaded fuel has created other
\ndangers associated with the increased use of aromatics in
\nunleaded fuel, especially in non-catalyst and poorly serviced
\ncars.<\/p>\n
Window: Uleadeed fuel has been promoted as a replacement to
\nleaded fuel but there are environmental problems associated with
\nunleaded fuel which may be more dangerous.<\/p>",
"url": "https:\/\/jawawa.id\/newsitem\/unleaded-petrol-safer-than-leaded-1447893297",
"image": ""
},
"sponsor": "Okusi Associates",
"sponsor_url": "https:\/\/okusiassociates.com"
}