Chapter 11Fossil Fuels

Overview • Energy Sources and Consumption• How Fossil Fuels are Formed• Coal– Coal Reserves and Mining– Environmental Impacts

• Oil and Natural Gas– Exploration for Reserves of Oil and Natural Gas– Environmental Impacts– Arctic National Wildlife Refuge

• Synfuels• US Energy Strategy

Energy Sources and Consumption

• Energy sources used to be local• Now they are worldwide– Fossil fuels (55.5% imported)– Nuclear energy– Electricity

• Energy consumption is different between developing and developed nations– 20% of world’s population use 60% of the world’s energy

sources (developed uses 8x’s more than developing)

• Per capita energy consumption of selected developed and developing countries

o Energy consumption in Energy consumption in the USthe US• Industries (production) Industries (production)

use the mostuse the most• Heating, cooling, and Heating, cooling, and

illuminating building is illuminating building is 1/31/3

Fossil Fuels

• Combustible deposits in the Earth’s crust– Composed of the remnants (fossils) of prehistoric

organisms that existed millions of years ago – Includes coal, oil (petroleum) and natural gas

• Non-renewable resource– Fossil fuels are created too slowly to replace the

reserves we use– We will have to transition to other sustainable

fuels in the future

How Are Fossil Fuels Formed?• 300 million years ago

– Climate was mild– Vast swamps covered much of the land– Dead plant material decayed slowly in the swamp environment

Plants include giant ferns, horsetails, and club mosses

How Are Fossil Fuels Formed• Over time, layers of sediment accumulated

over the dead plant material• Coal– Heat, pressure and time turned the plant material

into carbon-rich rock (coal)• Oil– Sediment deposited over microscopic plants – Heat pressure and time turned them into

hydrocarbons (oil)• Natural Gas– Formed the same way as oil, but at temperatures

higher than 100 °C

Coal• Occurs in different grades

– Based on variations in heat and pressure during burial

• Lignite • Subbitumimous• Bituminous• Anthracite• Most, if not all, coal deposits have been

identified– Primarily in northern hemisphere

Coal Types and Quality

• Lignite –poor quality, dark brown, 30% carbon, $11.41 (per 2000 lbs to mine), heat value 6000 btu/lb

• Subbituminous – Poor quality but better, dull black, 40% carbon, $7.12, heat value 9000 btu/lb

• Bituminous – also called soft coal, high sulfur , 50-70% carbon, $24.15 to mine, 13000 btu/lb

• Antracite- black, high quality, low sulfur,90% carbon, $40.90 to mine, 14,000 btu/lb (fig 10.1)

Coal

• US has 25% of world’s coal supplies

• Known coal deposits could last 200 years– At present rate of

consumption

2 Types of Coal Mining• Surface mining (right)– Chosen if coal is within 30m of

surface– mineral and energy resources

are extracted near Earth’s surface by first removing the soil, subsoil, and overlying rock strata

• Subsurface mining– Extraction of mineral and

energy resources from deep underground deposits

Surface mine near Wyoming

Environmental Impacts of Mining Coal

• Surface Mining Control and Reclamation Act (1977)– Requires filling (reclaiming) of surface mines after

mining• Expensive!

– Reduces Acid Mine Drainage– Requires permits and inspections of active coal mining

sights– Prohibits coal mining in sensitive areas

• Mountaintop Removal– Fills valleys and streams with debris– Most land destructive tecnique

Environmental Impacts of Burning Coal

• Releases large quantities of CO2 into atmosphere– Greenhouse gas

• Releases other pollutants into atmosphere– Mercury– Sulfur oxides– Nitrogen oxides

• Can cause acid precipitationDead trees enveloped in acid fog on Mt. Mitchell,

North Carolina

Making Coal Cleaner• Scrubbers• Fluidized Bed Combustion (below)

1.Coal and limestone suspended

2.Coal burns and limestone neutralizes most of sulfur dioxide

3.Heat converts water to steam

4.This powers industrial processes

Oil and Natural Gas• Oil and gas provide 60% of world’s energy– They provide 63% of US’s energy, 23% provided by coal

Petroleum Refining• Numerous hydrocarbons

present in crude oil (petroleum) are separated– Based on boiling point

• Natural gas contains far fewer hydrocarbons than crude oil– Methane, ethane, propane

and butane

Oil and Natural Gas Exploration

• Oil and natural gas migrate upwards until they hit impermeable rock

• Usually located in structural traps

Oil Reserves

• Uneven distribution globally

• More than half is located in the Middle East which includes Iran, Iraq, Kuwait, Oman, Qatar, Saudi Arabia, Syria, Yemen, and the United Arab Emirates

Natural Gas Reserves

• Uneven distribution globally

• More than half is located in Russia and Iran (app. 48% of worlds deposits)

How long will Supplies Last?• Difficult to determine and estimates vary• Depends on:

• How many more deposits How many more deposits will be locatedwill be located

• What technology might be What technology might be available to extract deeper available to extract deeper resourcesresources

• Changes in global Changes in global consumption ratesconsumption rates

o Experts indicate there Experts indicate there may be shortages in 21may be shortages in 21stst centurycentury Long lines at gas station as a result of the

OPEC oil embargo in 1973

Environmental Impacts of Oil and Natural Gas

• Combustion– Increase carbon dioxide and pollutant emissions

(nitrogen oxides/photochemical smog)– Natural gas is far cleaner burning than oil

• Production– Disturbance to land and habitat

• Transport– Spills- especially in aquatic systems– Ex: Alaskan Oil Spill (1989)

1989 Alaskan Oil Spill

Water currents caused the oil to spread hundreds of miles

1989 Alaskan Oil Spill• Exxon Valdez hit a reef and spilled 260,000

barrels of crude oil into sound• Largest oil spill in US history• Led to Oil Pollution Act of 1990

Worker attempting to cleanup rocky shoreline of Eleanor Island

Case in Point - Arctic National Wildlife Refuge

Synfuel and Other Fossil Fuel Resources

• Synfuel– A liquid or gaseous fuel that

is synthesized from coal and other naturally occurring sources

– Used in place of oil or natural gas

• Include:– Tar sands– Oil shales– Gas hydrates– Liquefied coal– Coal gas (right)

US Energy Strategy

• Objective 1: Increase Energy Efficiency and Conservation– Requires many unpopular decisions– Examples• Decrease speed limit to conserve fuel• Eliminate government subsidies

• Objective 2: Secure Future Fossil Fuel Energy Supplies– 2 oppositions: environmental and economic

US Energy Strategy

• Objective 3: Develop Alternative Energy Sources– Who should pay for this? Gas taxes?

• Objective 4: Meet the First Three Objectives Without Further Damage to the Environment

National Energy Policy (2005)