Fossil Fuels

Chapter 11Coal

FOSSIL FUELS 85% of the world’s

com 85% of the world’scommercial energy

mercial energy

COAL

OILNANANNATURAL GAS

FOSSIL FUELS85% Of the world’s commercial energy

COAL

OIL

Per capita commercial energy consumption in selected countries

Energy consumption in developed and developing countries

• Farmers in developing nations rely on their own physical energy or the energy of animals to plow and tend fields.

• Agriculture in highly developed countries involves many energy consuming machines, such as tractors, loaders. Additional energy is required to produce fertilizers and pesticides widely used in agriculture.

• Read Environews in page number 235 regarding energy for China.

Energy density and Energy efficiency

• Energy density: The amount of energy contained within a given volume or mass of an energy source. Gasoline has an higher energy density than does dry wood, which in turn has a higher density than wet wood

• Gasoline -> dry wood-> wetwood.

• Energy efficiency: a measure of the fraction of energy used relative to the total energy available in a given source. Energy efficiency ranges from 0 to 100%: use of natural gas for heating has an efficiency of close to 100% while the efficiency of burning natural gas to generate electricity has maximum efficiency of about 60%

Energy consumption in the United States

overall in U.S industries consume 42% buildings 33%Transportation 25%

Definition of Fossil Fuel

• Combustible deposits in earth’s crust, composed of the remnants (fossils) of prehistoric organisms that existed millions of years ago. Coal, oil (petroleum), and natural gas are the three types of fossil fuel.

• Coal is a black, combustible solid composed mainly of carbon, water, and trace elements found in earth’s crust; formed from the remains of ancient plants that lived millions of years ago.

Oil and Natural gas

• Oil is a thick, yellow to black, flammable liquid hydrocarbon mixture found in Earth’s crust; formed from the remains of ancient microscopic aquatic organisms

• Natural gas: A mixture of energy-rich gaseous hydrocarbons (primarily methane) that occurs, often with oil deposits, in Earth’s crust.

How Fossil Fuels Formed?

• http://video.google.com/videoplay?docid=3962309378012938462

• Reconstruction of a Carboniferous swamp• The plants of the Carboniferous period, 360 millions to

286 millions years ago, included giant ferns, horsetails and clubmosses that formed our present day coal deposits.

• Read page No.236-237 to know How coal, oil, and

Natural gas is formed.

Percent of proved recoverable coal reserves

Largest coal deposits are in the Northern Hemisphere. United States, Russia, China, Australia, India, Germany and South Africa. The United States has 25% of the world’sCoal supply.

Types of coal• Lignite: soft coal, brown, woody texture, moist and produces little heat. It is

used to fuel electric power plant.• Largest producer is in the United States is North Dakota• Subbituminous coal: relaitvely low heat value and sulfur content. Cola fired

power plants in U.S use this coal because of low sulfur value. It is found in Alaska and few Western States Montana and Wyoming.

• Bituminous coal: Also called soft coal, harder than lignite and subbituminous coal. It contains sulfur and causes severe environmental problems. Electric power plants use this coal as it produces a lot of heat. It is found in the Applachian region, in the Mississippi alley, and in central Texas.

• Anthracite or hard coal, dark, burns most cleanly, it produces the fewest pollutants per unit of heat released – as it does not contain large amounts of sulfur. Anthracite has the highest heat-producing capacity of any grade of coal.

• It is found in Pennsylvania

Heat value of coal types

Coal Mining

• Surface Mining: the extraction of mineral and energy resources near Earth’s surface by first removing the soil, subsoil, and overlying rock strata. ( if the coal bed is within 30 m (100ft) or so of the surface.

Subsurface mining Surface mining

Contd.,

• Subsurface Mining: when the coal is deeper in the ground this method is used.

• Advantages of surface mining:• Surface mining is less expensive and safer for

miners, and it generally allows a more complete removal of coal from the ground.

• Disadvantage: Disrupts the land much more extensively than subsurface mining.

• Cause several serious environmental problems.

Safety Problems Associated With CoalEffects on Health

• Underground mining is a hazardous occupation.• Miners have an increased risk of cancer and black lung

disease, a condition in which the lung are coated with inhaled coal dust, and the exchange of oxygen between the lungs and blood is severely restricted.

• 2000 miners in the United States die each year because of

the above said problems.

Black Lung diseaseRespiratory illness

Environmental Impacts of the Mining Process

• Before the passage of the 1977 Surface Mining Control and Reclamation Act (SMCRA) , abandoned surface coal mines were usually left as large open pits or trenches.

• Acid and toxic mineral drainage from such mines, along with the removal of topsoil, prevented most plants from naturally recolonizing the land.

• Streams were polluted with sediments and acid mine drainage, produced when rainwater seeps through iron sulfide mineral exposed in mine wastes.

• Landlsides occurred on hills as they were unstable from the lack of vegetation

Effects of Mining On Land

• Mountain top removal. This has leveled 15 and 25% of the mountaintops in Southern West Virginia, Kentucky, Pennsylvania,and Tennessee.

Mountain top removalCoal Sludge

Environmental Impacts of Burning Coal

Emission of Greenhouse Gases•Oxides of Sulfur •Oxides of Nitrogen•Carbon Dioxide•Toxics – Mercury•Acid Deposition

Effects of Acid Rain

• pH of 6.0 kills insects and crabs.• pH <5 kills fish, trees (decline of forest)

Making coal a cleaner fueluse of coal scrubber

Coal Scrubber

Scrubbers remove 98% of the sulfur and 99% Of the particulate matter in smokestack.

Contd.• Resource recovery: The process of removing any material-sulfur or metal,

for example-from polluted emission or solid waste and selling it as marketable product is known as resource recovery.

• The Clean Air Act Amendment of 1990 also directed the coal-burning power plants to cut sulfur-dioxide emissions

• Clean coal technologies.• Fluidized-bed combustion: A clean- coal technology in which crushed

coal is mixed with limestone to neutralize acid sulfur compounds produced during combustion.

Surface Mining Control and Reclamation Act (SMCRA) 1977

• Requires coal companies to resotre areas that have been surface mined, beginning 1977.

• Protects the environment by requiring permits and inspections of active coal mining operations and reclamation sites.

• Prohibits coal mining in sensitive areas such as National Parks, wildlife refuges, wild and scenic rivers, and sites listed on the National Register of Historic Places.

• It stipulates that surface-mined land abandoned prior to 1977 should be gradually restored.