Diesel Fuel
Petroleum fuel starts off as crude oil that's naturally found in the
Earth. When crude oil is processed at refineries,
it can be separated into several different kinds of fuels, including gasoline,
jet fuel, kerosene and, of course, diesel.
If you have ever compared diesel fuel and gasoline, you know that they are different. They
certainly smell different. Diesel fuel is heavier and oilier. It evaporates
much more slowly than gasoline -- its boiling point is actually higher than the
boiling point of water. You will often hear diesel fuel referred to as
"diesel oil" because it's so oily.
Diesel fuel evaporates more slowly because it
is heavier. It contains more carbon atoms in longer chains than
gasoline does (gasoline is typically C9H20, while diesel fuel is typically
C14H30). It takes less refining to create diesel fuel, which is why it
used to be cheaper than gasoline. Since 2004, however, demand for diesel has
risen for several reasons, including increased industrialization and
construction in China and the U.S.
Diesel fuel has a higher energy
density than gasoline. On average, 1 gallon (3.8 L) of diesel fuel
contains approximately 155x106 joules (147,000
BTU), while 1 gallon of gasoline contains 132x106 joules (125,000 BTU). This, combined with the improved
efficiency of diesel engines, explains why diesel engines get better mileage
than equivalent gasoline engines.
Diesel fuel is used to power a wide variety of
vehicles and operations. It of course fuels the diesel trucks you see lumbering
down the highway, but it also helps move boats, school buses, city buses,
trains, cranes, farming equipment and various emergency response vehicles and
power generators. Think about how important diesel is to the economy -- without
its high efficiency, both the construction industry and farming businesses
would suffer immensely from investments in fuels with low power and efficiency.
About 94 percent of freight -- whether it's shipped in trucks, trains or boats
-- relies on diesel.
A sample of diesel
fuel
During the big oil crisis in the 1970s, European car companies started
advertising diesel engines for commercial use as an alternative to gasoline. Those who tried it out were a bit disappointed -- the engines were very loud, and they would arrive home to find
their cars covered from front to back in black soot -- the same soot
responsible for smog in big cities.
Over the past 30 to 40 years, however, vast
improvements have been made on engine performance and fuel cleanliness. Direct
injection devices are now controlled by advanced computers that monitor fuel
combustion, increasing efficiency and reducing emissions. Better-refined diesel
fuels such as ultra-low sulfur diesel (ULSD) will lower the amount of harmful
emissions and upgrading engines to make them compatible with cleaner fuel is
becoming a simpler process. Other technologies such as CRT particulate filters
and catalytic
converters burn soot and reduce
particulate matter, carbon monoxide and hydrocarbons by as much as 90 percent.
Continually improving standards for cleaner fuel from the European Union will
also push the auto industries to work harder at lowering emissions -- by
September 2009, the EU hopes to have particulate matter emissions down from
25mg/kilometer to 5mg/kilometer .
You may have also heard of something called biodiesel.
Is it the same as diesel? Biodiesel is an alternative or additive to diesel
fuel that can be used in diesel engines with little to no modifications to the
engines themselves. It's not made from petroleum -- instead it comes from plant
oils or animal fats that have been chemically altered. (Interesting fact:
Rudolf Diesel had originally considered vegetable seed oil as fuel for his
invention.) Biodiesel can either be combined with regular diesel or used
completely by itself. You can read more about biodiesel in How.
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