Environmental Engineering Reference
In-Depth Information
The eighteenth-century Russian scientist Mikhail Lomonosov was the first to argue that
petroleum is biological in origin. Since then, scientists have confirmed that fossil fuels
develop in the absence of oxygen from decomposed organic matter, forming sedimentary
rocks rich in organic content. Organic matter is transformed, depending on the temperature
and pressure, into different types of hydrocarbons, and that is why we find gaseous, oily
or mixed reservoirs. While oil and natural gas were formed from plants, algae and animals
that died and sank to the bottom of primordial seas, coal was formed on land from decaying
forest soils (see
Figure 2.4
).
Figure 2.4.
How petroleum and natural gas are formed. Algae and animals died and
their bodies sank to the ocean floor. Over thousands of years, they were covered by layers
of sediments (silt and sand). Over millions of years, further layers of sediment compress
the organic matter, increasing pressure and turning the decaying organic matter into oil
and gas. Fundamental to the formation of a deposit is the occurrence of an impermeable
layer of sediment, which acts as an airlock.
Mineral oil came into use as a transport fuel following the invention of the internal
combustion engine in the late nineteenth century. Then, in the decade preceding the First
World War, oil began to occupy the central role it still holds in the transport economy. First,
shippingswitched from coal to crude oil because it ensured better flotation, higher speeds
and longer periods between refuelling. Next, mass production made cars affordable for a
massmarket. Then,therailways switched fromcoal todiesel engines, and,finally,fromthe
1950s, kerosene-fuelled mass air travel completed oil's inexorable conquest of passenger
and freight transportation.
Oil had three great advantages over coal: it is energy-dense, easy to transport by ship
or pipeline, and was, at that time, cheap and abundant. Its dominance over other fuels was
consolidated thanks to a steady decrease in price that began in the 1920s and only ended
during the oil crises of the 1970s. Since then, a few other snags have become apparent: like
other fossil fuels, oil is responsible for high greenhouse gas (GHG) emissions, and, more
than any other fossil fuel, oil implies political and social instability, since nearly two-thirds
of the world's reserves are concentrated in just six countries, five of them in the Middle
East.
