After reading this article you will learn about the environmental effects of using fossil fuel.
The use of fossil fuels (coal, oil, or natural gas) almost always entails some environmental degradation 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.
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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 by-products 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.
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The combustion of fossil fuels—whether coal, oil, or gas—inevitably produces a host of undesirable and often toxic by-products:
(a) Gaseous and particulate emission into the atmosphere,
(b) Liquid effluents, and
(c) Solid waste.
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In many countries, strict regulations were enacted 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 automobiles, trucks, and other vehicles, these mobile sources still contribute significantly to air pollution.
Perhaps the greatest long-term threat to the environment is the steadily increasing concentration of carbon dioxide in the atmosphere, for the most part a consequence of the combustion of fossil fuel. CO2 and some other so-called greenhouse gases may trap the outgoing thermal radiation from the earth, thereby causing global warming and other climate changes.
The consumption of vast quantities of fossil fuel by mankind causes many deleterious environmental and health effects. These effects start from the mining phase of the fossil fuels, through transportation, refining, combustion, and waste disposal. When coal is mined in deep shafts or in strip mines, mineral matter is separated at the mines by milling and washing.
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The residual slag may contain toxic, acidic, and sometimes radioactive material, which needs to be properly disposed of without endangering the environment and humans. Oil and gas well derricks, on and off-shore, are aesthetic eyesores and are the cause of oil spillage.
Oil and gas pipes may rupture and leak their contents. Oil tankers and barges spill on the average 4 million tons per year of crude and refined petroleum on our waterways and oceans.
Oil refineries are sources of:
(a) Toxic emissions through vents, leaks, and flaring; and
(b) Toxic liquid effluents and solid waste.
By far, the greatest environmental and health impact is due to fossil fuel combustion in furnaces, stoves, kilns, boilers, gas turbines, and the internal combustion engine, which powers our automobiles, trucks, tractors, locomotives, ships, and other mobile and stationary machinery.
The combustion process emits pollutants through smoke stacks, chimneys, vents, and exhaust pipes, such as particulate matter, oxides of sulfur and nitrogen, carbon monoxide, products of incomplete combustion, and volatile toxic metals. Some of these pollutants are toxic to humans, animals, and vegetation per se, whereas others transform in the atmosphere to toxic pollutants, such as ozone, organic nitrates, and acids.
The pollutants are adverted by winds and dispersed by atmospheric turbulence over hundreds to thousands of kilometers affecting sensitive population and biota far removed from the emission sources. Particles, besides containing toxic and potentially carcinogenic agents, often envelope whole sub continental areas in a haze that reduces visibility and the enjoyment of the landscape and a starry sky.
Great strides have been taken, especially in the more affluent countries, for limiting the emissions of air pollutants from the combustion sources.
For example, most particles can be filtered out of the flue gas by electrostatic precipitators or fabric filters. Sulfur oxide emissions can be reduced by wet or dry limestone scrubbers. Nitric oxide emissions can be reduced by catalytic and non-catalytic injections of chemicals into the flue gas.
The catalytic converter, which is now applied to gasoline fuelled automobiles in many countries, reduced the emissions of automobiles significantly compared to the uncontrolled predecessors. Diesel engines, with proper tuning, are also emitting less pollutant, although a magic box like the catalytic converter has yet to be found for diesel engines.
Alas, little or no emission control devices are applied to the myriad of dispersed sources, such as residential furnaces, stoves, and fireplaces, and smaller industrial facilities.