Environmental Engineering Reference
In-Depth Information
Sector
l/GJ
Oil recovery with steam injection
500-600 l/GJ
Natural gas extraction
300 l/GJ
Coal cleaning
20-50 l/GJ
Oil refining
200 l/GJ
Note: Figures are in litres used per GJ of energy produced.
Source:
Smil (
2008
) (modified).
6.2 The Great Polluters: Coal, Oil and Gas
Coal mining affects the environment by disturbing layers of soil and rock and exposing
them to rain or groundwater. This may lead to acid mine drainage, when water mixes with
the exposed rock, absorbing toxic levels of minerals and heavy metals. This water may
then leak out of the mines to contaminate groundwater and streams, affecting soil, plants,
animals, and humans.
For the first fifty years of the 'oil era', drilling for oil was an extremely dirty business.
The environmental destruction, both on land and in water, of early oil discoveries in
Azerbaijan (then part of the Russian Empire), Texas, Oklahoma, Mexico and Venezuela
was enormous. Spills, leaks, blowouts and fires were part and parcel of oil extraction well
into the twentieth century. The oil business transformed the coastal rainforest of Northern
Veracruz, Mexico, into a poisonous oily morass in just twenty years. Something similar
happened at Lake Maracaibo in Venezuela.
By the middle of the twentieth century, the oil industry had cleaned up its act
considerably, as a result of the pressure of environmental regulations such as the 1924 Oil
Pollution Act in the United States, and because of improved technology such as blowout
preventers. However, oil extraction continues to take a heavy toll on the Earth's land and
water resources, particularly in countries where environmental regulations are lax. A case
in point is the Niger delta in West Africa. Ever since oil was discovered there in the 1960s,
serious pollution has followed apace. By the 1980s, much of the land and fisheries of the
delta were heavily polluted. In 1992, the United Nations declared it to be the world's most
