Environmental Engineering Reference
In-Depth Information
revolution, with more powered items including computers and cellphones, has brought about great changes in
society with a resulting increase in energy consumption, even with the development of low-energy technology.
The four fuel sources of clean coal, methane hydrates, oil shale, and tar sands may help meet future global en-
ergy needs.
Fossil Fuel Resources and Use
Fossil fuels including coal, oil, and natural gas are nonrenewable. The journal
International Energy Outlook
(2004) predicts that by the year 2025 about 87 percent of human energy needs will be provided by fossil fuels.
Formed from plants and animals, fossil fuels are buried beneath the Earth's surface.
Societies around the world are dependent upon fossil fuels. Therefore, it is extremely useful to know how long
these resources are likely to last. Scientists are trying to answer just that question. Just as important is the ques-
tion of how much longer recovering fossil fuels will be technologically and economically viable. Many of the
Earth's most accessible fossil fuel deposits are already being depleted, forcing energy companies to go farther,
dig deeper, and work harder to recover remaining reserves, which adds to the remaining costs.
Coal, Oil, and Natural Gas
Coal, oil, and natural gas are the most commonly used fossil fuels. Although supplies are diminishing, con-
sumption is still increasing due to a growing worldwide population and increasing industrialization in develop-
ing countries.
Clean Coal
Coal is the dirtiest and most abundant of the fossil fuels. Clean coal refers to the process of removing the pollu-
tants that have a harmful effect on the environment. Technologies include washing coal to remove minerals and
impurities and removing the sulfur dioxide and carbon dioxide from the flue gases. Cleaner-combustion tech-
nologies are being developed to make the burning of coal more efficient and help reduce contaminants during
the combustion process. For example, coal can be converted into synthetic gas (syngas) in a process called
gas-
ification.
Or the impurities in coal can be removed and used in other products. Treating coal-produced flue
gases with steam can remove SO
2
and CO
2
. Finally, researchers are developing carbon capture and storage
(CCS) technologies to capture and store CO
2
emissions from coal.
The world's first "clean coal" power plant began generating energy in September 2008 in Germany. Due to the
high cost of the technology, the German government owns the plant. The power plant captures CO
2
and acid-
rain-producing sulfides. The CO
2
is compressed into liquid and stored. Future plans may inject liquid CO
2
into
depleted natural gas fields.
Formation of Coal
Coal is formed in an
anaerobic environment,
one in which there is no oxygen. A swampy, heavily vegetative
environment is ideal for forming coal. As plant matter falls into the swamp, it is quickly covered in mud. Over
time it becomes deeply buried, and the plant matter becomes compressed as more and more mud is deposited
on top of it. The pressure from the weight squeezes the liquid out of the dead plant material, leaving behind the
carbon matter to form the complex chains found in coal. Some 300 million to 360 million years ago, such en-
vironments were widespread throughout the world, and much of the coal we use today was formed then.
