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Fossil Fuels and Emissions
Fossil fuel burning in power stations for electricity releases gases into the atmosphere, which constitute air pollution.
CoalCoal is a solid fuel formed over millions of years by the anaerobic decay of vegetation. Coal is widely used in the generation of electricity as it constitutes a highly concentrated energy source.
It is, however, not a "clean" fuel in comparison to natural gas; when burnt it releases significant amounts of pollution into the atmosphere in the form of carbon dioxide (CO2), sulphur dioxide (SO2) and oxides of nitrogen (NOx). CO2 is a greenhouse gas, and as mankind adds more to the atmosphere, it may be responsible for global warming. SO2 and NOx are the major contributors to acid rain.
Air pollution from the burning of coal in the first part of this century led to huge smog problems in the UK, particularly in London. In response to the Great London Smog in 1952, during which 4,000 people died, the Clean Air Act of 1956 was introduced. This prevented the burning of coal in towns and cities and required factories and power stations to erect taller chimneys or stacks which disperse plumes of pollution high into the air.
Oil is formed from the remains of marine micro-organisms. As they accumulate on the seafloor over millions of years they gradually infiltrate the microscopic cavities of the sea floor sediment and rock where they decay. The resulting oil remains trapped in these spaces, forming hydrocarbon reserves which can be extracted through large drilling platforms.
Many sites of major oil fields occur where continental margins have been created by the break-up and rifting apart of landmasses. It was in such areas that the majority of the world's oil was formed.
In the early 1970s, approximately 40% of global fossil fuel use came from oil, but during the 1990s this figure has decreased. The United States consumes about a quarter of all oil extracted around the world. Reports have shown that most of the developed nations would be unable to function efficiently under a severe oil shortage situation. Consequently, nations are looking to invest in alternative energy resources.
Improved energy efficiency has caused oil consumption to decline in many developed, industrialised countries, as well as shifts to other fuels such as natural gas and nuclear energy. Decreasing use of oil is also resulting from tougher environmental restrictions concerning its use in some regions.
Natural gas is formed in the same way as oil, from the remains of marine micro-organisms, and is also found throughout the same regions of the world.
From the mid-1960s, up until the present day, there has been a dramatic increase in the amount of proven reserves of natural gas. Consequently, natural gas has become the fastest-growing energy resource. The present global use of natural gas is approximately 20% of all fossil fuel use, and this figure is predicted to rise in the future. Natural gas provides an alternative to oil or coal in the provision of energy, and in terms of pollution it is a cleaner fuel.
In the mid-1990s it was predicted that global natural gas reserves would last only for the next 120 years, whereas economically recoverable coal reserves might last for another 1,500 years. However, if it becomes economically viable to tap less accessible reserves, then natural gas may possibly last for almost 400 years.
Leakage and losses of methane from distribution systems, including pipelines, oil/gas wells, and domestic use, contribute to the anthropogenic (man-made) emissions of greenhouse gases. Annual leakage rates are estimated to range between 1-5% of the total amount of natural gas used each year in Europe and North America, and up to 10% in countries such as the former Soviet Union.