Chapter 16: Fossil Fuels: Energy Use and Impacts
Fossil fuels – highly combustible substances formed from the remains of organisms from past
geologic ages. Today we mostly use oil, coal, and natural gas. Considered nonrenewable.
Fossil fuels are indeed formed from fossils
• Fossil fuels we burn today were formed from the tissues of organisms that lived 100–
• 500 million years ago (Carboniferous Period)
• Produced when organic material decomposed down in anaerobic conditions
• Little or no oxygen
• Bottoms of deep lakes, swamps, and shallow seas
• Organic matter heated, compressed, altered, and eventually converted into crude oil,
natural gas, or coal = maturation
• Fossil fuels are produced only when organic material is broken down in an anaerobic
environment, one that has little or no oxygen
• Aerobic decomposition: presence of air, bacteria and other organisms that use oxygen
break down plant and animal remains into simpler carbon molecules that are recyceled
through the ecosystem
• Kerogen: organic matter that accumulates at the bottoms of such water bodies
undergoes decomposition, forming an oil precursor
Energy resources can be renewable, inexhaustible, or nonrenewable
• Fossil fuels are nonrenewable – they are replenished, but not on a humanly accessible
• Even renewable energy resources can become nonrenewable if they are used at a rate
that is greater than the rate of replenishment.
• Mineral resources can be recycled, but energy resources cannot (2nd law of
Developed nations consume more energy than developing nations
• Industrialized nations!
• Use energy for transportation, industry, home/business and industrial needs!
• Developing nations
• Use energy for subsistence activities
• Agriculture and food preparation!
• Manual energy, animal energy, and biomass energy are more common than in
industrialized nations It takes energy to make energy
• Net energy = the difference between energy returned and energy invested!
• Energy returned on investment (EROI) = energy returned/energy invested!
• ratios decline when we extract the easiest deposits ﬁrst and then must work
harder to extract the remaining reserves
• Petroleum (oil, natural gas) formation: shallow marine environment!
• Coal formation: terrestrial swamp environment
• fossil fuels were formed from the tissues of organisms that lived 100–500 million years
ago (Carboniferous Period)!
• produced when organic material decomposed down in anaerobic conditions!
• organic matter heated, compressed, altered, and eventually converted into crude oil,
natural gas, or coal = maturation
Coal is the world’s most abundant fossil fuel
• Coal = woody plant material, compressed and altered to form dense, solid carbon
• Contains lignin, a tough organic constituent of plants
• Coal has a very long history of use
• The Romans used coal for heating in the second and third centuries in Britain
• The Chinese have used coal for 2,000–3,000 years
• Commercial mining began in the 1700s
• Coal and the steam engine helped drive the Industrial Revolution and the steel
• In the 1880s, people used coal to generate electricity
• Coal forms from burial of woody plant matter
• Sulphur, mercury, arsenic, other trace metals!
• •coal in the eastern Canada is high in sulphur because it was formed in marine
• When high-sulphur coal is burned, it releases sulphates; contributes to smog and acidic
Coal varies in quality • Peat = organic material that is broken down anaerobically but remains wet, near the
surface, and not well compressed
• Widely used as a fuel in Britain; abundant in Canada
• Four main grades of coal
• Lignite = least compressed; softest; lowest energy
• Anthracite = most compressed; hardest; has the most Energy
Coal is mined from the surface and from below ground
• Subsurface mining = underground deposits are reached by digging networks of tunnels
• Strip mining = heavy machinery removes huge amounts of earth to expose and extract
• Mountaintop removal = in some cases, entire mountaintops are cut off to obtain the coal
Coal is mined in two main ways
• Subsurface - Straight down hole from surface
• Strip mining - Gradual digging of land
Coal mining affects the environment
• Strip mining causes severe soil erosion and chemical runoff!
• Acid mine drainage!
• Mountaintop removal causes enormous damage!
• Mining companies must restore landscapes, but the impacts are still severe
Coal mining is hazardous to human health
• inhalation of coal dust can lead to fatal black lung disease!
• coal dust explosions and mine collapse – coal mining is the most dangerous type of
Oil is the world’s most-used fuel
• People have used solid forms of oil (i.e., tar) for thousands of years
• Modern extraction and use began in the 1850s
• First bottled and sold as a healing aid, but it is carcinogenic • “Rock oil” used in lamps and as a lubricant
• Edwin Drake drilled the world’s first commercial oil well, in Titusville,
Pennsylvania, in 1859
• Petroleum products have many uses
Heat and pressure underground form petroleum
• Oil, crude oil, or petroleum (oil and natural gas)
• Crude oil = a mixture of hundreds of different types of hydrocarbon molecules
• Formed 1.5–3 km underground
• Dead organic material, buried in marine sediments and transformed by time,
heat, and pressure
• Marine organic matter – contains lipids (waxes, fats)
• Refineries separate crude oil into components such as gas, tar, and asphalt
• Cracking, distilling
Petroleum geologists infer the location and size of