Environmental Engineering Reference
In-Depth Information
9
CHAPTER
Environmental Effects
of Fossil Fuel Use
9.1
INTRODUCTION
The use of fossil fuels (coal, oil, or natural gas) almost always entails some environmental degra-
dation and risk to human health. The negative impacts start at the mining phase, continue through
transport and refining, and conclude with the fuel combustion and waste disposal process.
Underground (shaft) mining of coal has claimed thousands of lives throughout the centuries,
because of explosions of methane gas in the mine shafts and also because of the inhalation of coal
dust by the miners. At the mine mouth, mineral and crustal matter, called slag, is separated from the
coal. The slag is deposited in heaps near the mine, thus despoiling the landscape. In recent times,
most of the mined coal is crushed at the mine. The crushed coal is “washed” in a stream of water
in order to separate by gravitational settling the adherent mineral matter, thereby beneficiating the
coal prior to shipment. The “wash” usually contains heavy metals and acidic compounds, which,
if not treated, contaminates streams and groundwater. Surface (strip) mining, which is much more
economical than shaft mining, causes scarring of the landscape. Only recently were there introduced
some regulations in the United States and other countries to ensure the restoration of the wounds
caused by the removal of overburden of the coal seams, and recovery of the pits and trenches after
the coal has been exhausted.
On- and off-shore oil and gas drilling produce piles of drilling mud, along with an unsightly
vista of oil and gas derricks. Also, there is the risk of crude oil spills, and explosions or fire at oil
and natural gas wells.
Transport of coal, oil, and gas by railroad, pipelines, barges, and tankers carry the risk of spills,
explosions, and collision accidents. In the refining process, especially of crude oil, toxic gases are
emitted into the air or flared. Usually, some liquid and solid byproducts are produced that may be
toxic. Strict regulations must be enforced to prevent the toxic wastes from entering the environment
and thereby threatening humans, animals, and vegetation.
The combustion of fossil fuels—whether coal, oil, or gas—inevitably produces a host of
undesirable and often toxic byproducts: (a) gaseous and particulate emissions into the atmo-
sphere, (b) liquid effluents, and (c) solid waste. In many countries, strict regulations were en-
acted as to the maximum level of pollutants that can be emitted into the air or discharged into
surface waters or the ground from large combustion sources, such as power plants, industrial
boilers, kilns, and furnaces. However, the smaller and dispersed combustion devices, such as
residential and commercial furnaces and boilers, are not regulated, and they do emit pollutants
into the air. While great strides have been taken in many countries to control emissions from
226
