Environmental Engineering Reference
In-Depth Information
that includes the removal of water or water vapor, acid gas, and mercury. Natural gas also can be processed to
obtain methane, ethane, propane, butane, and pentane. A small amount of odorant is added to give the gas a
smell reminiscent of rotten eggs. Since natural gas is odorless, an odorant is added to help detect leaks that
could otherwise create fires and explosions or be harmful if inhaled.
Synfuels
Synthetic fuels, or
Synfuels,
are liquefied fuels obtained from nonpetroleum sources such as coal, natural gas
or biomass feedstocks through chemical conversion. For example, diesel and jet fuel that is made from coal are
synfuels. Some synfuels are derived from waste, such as plastic or rubber. Daily production of synfuels is over
240,000 barrels with additional projects in development.
Advantages and Disadvantages of Synfuels
Advantages
Disadvantages
Once converted, synfuels can be trans-
ported
Synfuels are not efficient, with minimal net energy yield.
Synfuels cause less air pollution than
conventional coal when combusted.
Expensive production facilities.
Synfuels are uneconomical.
Synfuels would diminish coal reserves.
There is an increased environmental impact due to mining of coal,
processing into synfuels, and the burning of synfuels.
World Reserves and Global Demand
Fossil fuels (coal, crude oil, and natural gas) are nonrenewable resources, and eventually their reserves will run
out. There has been much discussion and debate about how much of each fossil fuel remains. Adding to the
difficulty in predicting a date at which fossil fuel reserves will run out is the difficulty in predicting demand as
the world's need for energy increases with population growth and the industrialization of more countries. The
world reserves and global demand for three fossil fuels are:
•
Coal:
By far the largest reserves of natural fuels are the various types of coal. The known reserves of coal
are estimated to last about 200 years at the current rate of consumption. However, if consumption in-
creases at the conservative rate of 5 percent per year, that figure drops to 86 years. Unknown reserves are
estimated to last another 1,000 years. The largest reserves of coal are in Australia, China, Russia, and the
United States.
•
Crude oil:
Of the three fossil fuels, the known reserves of crude oil are estimated to last about 45 years at
current consumption and will dramatically decrease if consumption increases. The largest reserves are in
the Middle East, which increases the potential for disruption in the world oil supply due to unstable gov-
ernments, friction between the countries in the Middle East, and the recent wars in Iraq.
•
Natural gas:
At current consumption rates, the known reserves of natural gas are estimated to last 60
years. Europe has approximately 42 percent of the known reserves, while the Middle East has about 34
percent and the United States has about 3 percent.
Environmental Advantages and Disadvantages of Fossil
Fuels
