Chapter 10: Fossil Fuels

Fossil FuelsFossil fuels are composed of partially

decayed remnants of organisms.

They are nonrenewable resources.

• We have a finite (limited) amount that is being depleted

• Produce pollutants such as CO2, CO, SO2, NO3

A. How Fossil Fuels Were Formed

• Fossil fuels were formed in vast swamps that were filled with plant species that had long been extinct.

• They decayed little after death since they were covered with water.

• Over time, more and more dead plants built up and as a result, layers of sediments accumulated, forming layers that covered the plant material into a carbon-rich rock called coal.

Coal

• This substance was formed when partially decomposed plants were exposed to large amounts of heat and pressure for eons (long periods of time).

• Coal produces more CO2 emissions per unit of heat than other fossil fuels.

Coal

• Formed when partially decomposed plants were exposed to large amounts of heat and pressure for long periods of time.

• Produces more CO2 emissions than any other fossil fuel.

Types of Coal

• Lignite-soft coal that is low in sulfur and produces less heat in comparison to other grades of coal

• Sub-bituminous-intermediate grade coal between lignite and bituminous. Low hear value and sulfur content.

• Bituminous- “soft coal” that is high in sulfur and produces lots of heat

• Anthracite- “hard coal” that is low in sulfur and produces the most heat and less pollution

Coal Reserves

• Coal is present in greater quantities than oil or natural gas.

• Present coal reserves could last 200 years at our present rate of consumption however the harm to the environment would be more substantial.

Mining of Coal

• Subsurface mining – underground coal mining that is dangerous and unhealthy. Can cause black lung disease.

• Surface mining-disturbs large land areas and is expensive to restore the land. Advantages include it being healthier , a better extraction of coal, and less expensive. On the other hand, it disrupts the land more than subsurface mining.

Mining of Coal

• In Surface mining the use of draglines to remove mountain tops is one of the most destructive types of surface mining.

• Strip Mining is the worst type of surface mining. It creates spoil banks or hills of loose rock.

Problems with mining coal1) Landslides – They occur on hills that were unstable due to the lack of vegetation.

• 2)Can cause black lung disease.

• 3) Acid mine drainage – This is produced when rainwater seeps through iron sulfide minerals exposed in mine wastes and carries sulfuric acid to nearby lakes and streams.

• 4) Mountaintop removal – The dragline takes huge chunks out of a mountain to reach the coal located below.

Surface Mining Control & Reclamation Act (SMCRA)

• Requires that surface-mined lands be restored to make the land usable again.

• Was passed due to carbon dioxide emissions from coal, inability to reduce or eliminate CO2 from combustions of coal, and there was acid deposition from soft coals that contain sulfur.

Controlling SulfurFluidized-bed combustion is a cleaner coal-

burning process that removes sulfur from coal combustion (but not CO2).

• Scrubbers can also reduce sulfur escaping from coal combustion but not the CO2. These are often placed in smokestacks to reduce emissions.

Cleaner ways to mine coal

• Resource recovery makes scrubbers more desirable

Oil & Natural Gas

• Occur in structural traps such as anticlines, the upward folding of rock layers, and salt domes, underground columns of salt.

• Will probably be gone by the end of the 21st century

• Mostly located in the Middle East

• Oil was formed when large numbers of microscopic aquatic organisms died and settled in the sediments.

• Their decomposition depleted the small amount of O2 that was present in the sediments.

• The resultant oxygen-deficient environment prevented further decomposition and the dead remains were covered and buried deeper into the sediments.

• The heat and pressure aided in the conversion of these remains to hydrocarbons, known as oil.

Energy Consumption in Highly Developed and Developing Countries

Oil & Natural Gas•Energy Policy & Conservation Act in 1975 as a result of problems with Oil

dependency.• The Strategic Petroleum Reserve was created which contains up to one billion

barrels of oil stored in Salt mines along the Gulf of Mexico.

      

Environmental problems related to Oil & Natural Gas

• 1989 Exxon Valdez was the largest spill in U.S. history• 1991 Persian Gulf War “spill” (20x larger than the Exxon

Valdez spill)

• CO2 from Oil and natural gas combustion releases copious amounts of CO2.

• Nitrogen Oxides and sulfur oxides are also released from the combustion of Oil and Natural Gas. (acid rain)

Exxon Valdez Oil Spill

• The Exxon Valdez spilled 260,000 barrels of crude oil into the Prince William Sound along the coast of Alaska. This led to a decline in bird populations, sea otter populations, and the salmon migration was disrupted. To clean up, they mechanized stream cleaning and rinsing, which killed shoreline organisms. They left the area with contaminated shorelines.

Exxon Valdez Picture

Exxon Valdez

Exxon Valdez Picture

Persian Gulf Oil Spill

• In the Persian Gulf oil spills, crude oil was dumped into the Persian Gulf. Many oil wells were set on fire, and lakes of oil spilled into the desert around the burning oil wells. Cleanup efforts along the coastline and the desert were hampered by the war.

Law because these spills

• The Oil Pollution Act of 1990-This legislation is liable for damages to natural resources resulting from a catastrophic oil spill, including a trust fund that pays to clean up spills when the responsible party in unable to.

• This act also requires double hulls on all oil tankers that enter the U.S. waters by 2015.

Case in Point: The Arctic National Wildlife Refuge

Alternatives•      Synthetic fuels like tar sands (oil sands), oil shales, gas hydrates, liquid coal, and coal

gas.•      Coal gasification: Converts solid coal into

Methane by heating and mixing with steam.•      C + H2O CH4 + CO2

•      Coal liquefaction: process that produces a liquid fuel that burns cleaner than solid coal.

•      These can have some of the same undesirable effects that fossil fuels have.

Move towards conservation (Car pooling, insulation in homes, efficient automobiles,

light bulbs, & appliances. 

55mph speed limit designed to reduce pollution and use of fossil fuels as well

as safety

Energy Efficiency

• SUV’s (Sport Utility Vehicles) use large amounts of gasoline and other petroleum products.

Review

• 1) The world’s largest oil spill was the Persian Gulf

• 2) Oily rocks that can be crushed and heated to produce oil is oil shale.

• The most common type of coal is bituminous coal.• Most of the oil reserves is in the Middle East• The most abundant fossil fuel is coal• Anthracite coal burns the hottest and produces the

least pollution.

Review

• Increasing the average global temp. due to increasing amounts of CO2 in the atmosphere is global warming.

• Petrochemicals can be used to produce a variety of everyday products.

• Technology used to remove sulfur oxides from smoke stack emissions are scrubbers.

• Oil produces few sulfur oxides, but lots of nitrogen oxides• Nitrogen oxide emissions are produced mainly by

automobiles• Acid precipitation is linked to the worldwide forest decline.

• Matching:1. hydrocarbons –

2. highwalls

3. scrubbers

4. resource recovery

5. fluidized-bed combustion

6. petroleum

7. liquefied petroleum gas

8. cogeneration

9. anticline

10. salt dome

11. tar sands

12. oil shales

13. gas hydrates

14. coal gas

a. burns a coal-1imestone mixture; reduces pollution

b. a synfuel abundant in Venezuela and Alberta, Canada

c. using natural gas to produce electricity and generate steam for water and space heating

d. cliffs of excavated rock at a surface mine

e. desulphurization systems; reduce coal's sulfur emissions

f. a liquid composed of many hydrocarbon compounds

g. used for home lighting and heating until replaced by oil and natural gas

h. molecules that make up oil

i. underground, ice-encrusted natural gas

j. rock strata, folded upward, that may trap oil or natural gas

k. creates a marketable product from industrial waste

1. used mainly for heating and cooking in rural areas

m. an underground column of salt that may trap oil or natural gas

n. a synfuel that is not yet cost-efficient to utilize