Environmental Engineering Reference
In-Depth Information
quantities. The increased use of municipal solid waste (MSW) as a feed-
stock for renewable fuels is also likely to grow.
In spite of significant problems, many are optimistic about the role of
biomass for alternative fuels in the future. The U.S. Department of Energy
believes that biofuels from nonfood crops and MSW could potentially cut
U.S. oil imports by 15 to 20%. Ethanol industry members believe that the
capacity for producing that fuel alone could be doubled in a few years and
tripled in five years.
METHANOL
Methanol, which is also known as wood alcohol, is a colorless and
odorless liquid alcohol fuel that can be made from biomass, natural gas,
or coal. It is the simplest alcohol chemically and it may be used as an au-
tomobile fuel in its pure form (M100), as a gasoline blend of typically 85%
methane to 15% unleaded gasoline (M85). It is also used as a feedstock for
reformulated gasoline. M100 or pure methanol may be used as a substi-
tute for diesel. In M85, the gasoline is added to color the flame of burning
fuel for safety reasons and to improve starting in cold weather.
Methane has an invisible flame and can be explosive in a closed
space such as a fuel tank although it is less flammable than gasoline and
results in less severe fires when ignited. Colorants may be added to help
identify the flame and baffles or flame arresters at the opening of the tank
can be used to repress the accidental ignition of methanol vapors.
One of the considerations regarding the use of methanol as a fuel
is that it emits higher amounts of formaldehyde, which is a contributor
to ozone formation and a suspected carcinogen, compared to gasoline.
Proponents of methanol dispute this, saying that one-third of the form-
aldehyde from vehicle emissions actually comes from the tailpipe, with
the other two-thirds forming photochemically, once the emissions have
escaped. They state that pure methanol vehicles produce only one tenth
as much of the hydrocarbons that are photochemically converted to form-
aldehyde as do gasoline automobiles.
If methanol utilization is to be increased, production needs to be-
come more efficient and the infrastructure improved to make it more com-
petitive. A major source of methane has been natural gas, since this has
been the most economical source. Although the United States has both
natural gas and coal, these are both nonrenewable resources.
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