Transcript AP EXAM REVIEW

AP EXAM REVIEW
PPT #1
Coal Gasification
Method of extracting gases, primarily hydrogen
gas, from coal while reducing/omitting
emissions of nitrogen oxides, sulfur dioxides,
Carbon dioxides, and mercury.
Watch http://www.youtube.com/watch?v=p20iJEcKd_c
The Hydrogen gas can then be used in a fuel cell.
Watch http://www.youtube.com/watch?v=esuAlB4NVi0&feature=topics
Energy
• Defined as the ability to do work
– Work is force acting across a distance
– Power is the rate at which work is done
– Food energy is measured in calories
• A calorie is the amount of energy that can raise the
temp of 1 gram of water 1°C
• A kilocalorie (Calorie) is 1000 calories
• A Newton is the force needed to accelerate 1kg of mass
1 m/s
Energy Units
• 1 joule (J)= the force exerted by a current of 1 amp per
second flowing through a resistance of 1 ohm
• 1 watt (W)= 1 joule per second
• 1 kilowatt-hour (kWh)= 1000 watts exerted for 1 hour
• 1 megawatt (MW)= 1 million watts 106
• 1 gigawatt (GW)= 1 billion watts 109
• 1 petajoule (PJ)= 947 billion BTU, or 0.278 billion kWh
• 1 British Thermal Unit (BTU)= energy to heat 1lb of
water 1°F
• 1 standard barrel (bbl) of oil= 42 gal (160L) or 5.8 BTU
• 1 metric ton of standard coal= 27.8 million BTU
A little history
• Humans began using domesticated animals more
than 10,000 years ago to assist us with our work
• Wind and water were used to grind grain, cut
timber, and provide other necessary energy
• Steam engine development reduced available
wood supplies and increased the use of caol
• Coal fell into decline when it was discovered that
petroleum could be used for many of the same
applications
• 86% of the world’s energy use is supplied by fossil
fuels
• In the past, developed countries have used far
more energy than developing countries
• With rapid industrialization and economic growth
in China and India, developing countries will
consume a greater proportion of energy that they
have in the past
• Political turmoil in the Middle East has impacted
fuel prices
– OPEC embargo 1973
– Iranian Revolution in 1979
– Plus hurricane Katrina effected prices
World Energy Use
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Oil 40%
Coal 23%
Natural Gas 23%
Nuclear 7%
Renewable 7%
American Energy Use
• Oil 43%
• Vast coal reserves, so we use more coal than
natural gas, even though it is more polluting
• Nuclear power 8%
• Renewable sources 6%
• U.S. is world’s largest oil importer
– We use foreign oil for 75% of our supply
• Canada and Saudi Arabia supply most
U.S. Energy Use
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Industry
Mining and smelting
Chemical energy
Residential and commercial building use ~20%
– Heating, lighting, cooling, and water heating
• Transport 27%
– 98% from petroleum
Net Energy Production
• It takes tremendous amounts of energy to mine
coal and transport the coal to a power plant
• 70% is lost in energy conversion at the power
plant and 10 % more during electrical
transmission
• 75% of the energy lost as petroleum is converted
into fuels, transported, and burned in vehicles
• Natural gas is the greatest efficiency
– Loses about 10% and produces less CO2 than coal or
oil
Coal
• Fossilized remains of ancient plant material
– Formed during the Carboniferous period
• Coal Formation
1. Peat: peat bogs still exist throughout the world
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Burned for fuel
Sedimentary rock
2. Lignite: softest coal, lots of moisture, woody texture,
western US
3. Bituminous coal is the most common, high sulfur
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Greater heat capacity than lignite
Appalachians, Mississippi, Central Texas, Great Lakes
4. Anthracite: greatest heat capacity
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95% carbon, little sulfur; so cleanest burning
metamorphic rock
Pennsylvania
Coal Reserves
• Most abundant fossil fuel
– Proven reserves for 200 years
– Not equal distribution of reserves
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U.S.
Russia
China
India
Australia
Uncommon in Africa, Middle East, Central and South
America
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Coal Mining and Environmental
Damage
TWO major types
– Surface (strip mines)
• Remove overburden, remove coal, overburden fills in new strip
• Mountain top removal in Appalachians
– Places overburden in nearby valleys
– Miners apply for a variance in Surface Mining Control and
Reclamation Act
– Subsurface
• Found primarily in Eastern U.S.
• Bituminous and anthracite coals
• One of most dangerous: toxic gases, explosions, cave-ins
– One mine in China has been burning for 400 years
– One in Pennsylvania has been burning for 40 years
– Mines now have exhaust fans, protective masks
• Mines can strike groundwater and contaminate w/ heavy
metals
Environmental Impact of Mining
• Destroys natural vistas
– Creates unsightly scars on the earth’s surface
• Disturbs habitat for countless species
• Increases erosion
• Contaminate groundwater with acids + heavy
metals
– Iron pyrite frequently found in coal mines in Eastern
US dissolves in water and migrates into streams,
acidifying those ecosystems
• Underground mining creates tailings (lots of solid
waste) with heavy metals present
Coal Combustion
• Emits more CO2 per unit of heat than any other fuel
• Releases SO2 and NOX
– Acid deposition
• Releases more nuclear radiation than any nuclear
power plant
• Fly ash contains heavy metals: arsenic, lead, cadmium,
mercury and zinc
• Responsible for 25% of the mercury released in the US
• Bottom ash must be disposed of in a landfill
• Thermal pollution associated with steam production
used in turbines
Methods to Remove SO2 From Coal
Emissions
• Sulfur dioxide may be reduced precombustion
– Using higher grade of coal (anthracite)
– Washing the coal to remove excess sulfur
– Convert coal to gas (coal gasification) or oil (coal liquefaction
• Sulfur dioxide may be reduced during combustion
– Using fluidized bed combustion by burning the crushed coal with
crushed limestone
• Sulfur combines with the calcium to form calcium sulfate or gypsum
• Post combustion methods include
– Using catalytic converters to oxidize the sulfur to yield sulfur
compounds
– Lime scrubber in a smokestack may also be used
– Wet scrubber: slurry of lime mixed with water is sprayed across the
exiting gases, sulfur mixes with the calcium forming the calcium
sulfate, which falls to the bottom of the smokestack as bottom ash
http://www.howstuffworks.com/catalytic-converter.htm
Methods to Remove Particulates from
Coal Emissions
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By burning coal with a low ash content
Most removal is post combustion
Resultant particle mixture is often hazardous waste
Bag filters are a series of bags, (like a vacuum) which catch
the particulates as they rise in the smoke
– Bags are periodically emptied of their ash
• Electrostatic precipitators remove 99%
– Pass coal emissions past a series of charged plate, charging the
particulates, which then bind to an oppositely charged plate
• Cyclone collectors create a vortex in a smokestack
– Causing the particles to collide and fall to the bottom of the
stack as bottom ash
Oil
• Derived from ancient organisms buried in sediment,
subjected to heat and pressure
• Usually found in conjunction with natural gas in porous rock
– Held in place by impermeable sediments such as shale
• Primary recovery: oil moves into wells: where it is
pumped to the surface
• Secondary recovery: the yield is increased by injecting
water into a second well to force oil toward the oil
drilling well
– Primary and secondary recovery allow 15-40% of a well’s reserve
to be removed
• Tertiary recovery: involves injecting steam or carbon
dioxide into wells to stimulate the remaining heavy oil
to flow to obtain another 5-15% of the oil remaining in
the well
Oil Reserves
• Oil deposits have uneven distribution in world
– Present on every continent
– 2/3 of proven reserves in Middle East
– U.S. has 3% of proven reserves mainly in Gulf of
Mexico
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Provides 25% of US oil and 20% of natural gas
Oil in Gulf removed by stationary and floating platforms
U.S. produces about 8 million barrels a day
If oil prices rise then reserves increase with economic
feasibility
ANWR Controversy
• Alaska Arctic national Wildlife Refuge
– Estimates run as high as 12 billion barrels
– Plain is calving ground of caribou and summering site
for snow geese, swans and other migratory waterfowl
– Polar bears, arctic foxes and wolves found in this
refuge
– Argue that increased fuel efficiency will save same
quantity of oil
– Others argue that there will be little damage from
drilling
Environmental Costs
• 1989 EXXON Valdez released millions of gallons in
Prince William Sound, Alaska
• 1990 Oil Pollution Act allows EPA to better
regulate spills, oil storage facilities and oil tankers
• One of worst spills: Iraqi army in Kuwait dumped
a huge volume of oil into the Persian Gulf in 1991
(unknown quantity)
• Drilling leads to erosion and habitat disruption
• We are seeing affects of spill in Gulf of Mexico
May 2010
Refining
• Distillation/ refining heats petroleum to
remove the various components
– Gasoline, kerosene, diesel fuel, lubricating oil,
heavy gas oil, and asphalt
– Products made from petroleum include plastics,
paraffin wax, mineral oil, petroleum jelly, dyes,
pesticides, and industrial solvents
– Burning gasoline releases CO2 and NOX
• NOX contributes to smog formation and acid deposition
Tar Sand
• Oil can be derived from tar sand or oil shale
– Tar sands are sandstone deposits infused with a
thick oil know as bitumen
– The oil is too thick to pump out in an oil well, so it
must be heated to remove it from a well as a
liquid or mined
– Steam contaminates large amounts of water
– The oil has to be refined to remove the sand
– Several U.S. states have tar sand deposits
• Canada has tremendous amounts in Alberta
Oil Shale
• Is a sedimentary rock composed of a variety of
heavy oils called kerogen
• Oil shale is surface mined, then crushed and
heated to remove the oil
• Large deposits of oil shale in the U.S. mainly in
Colorado, Utah and Wyoming
– Recovery is not economically feasible
– Process requires large amount of water to refine
the oil, but the resource is in arid part of country
Natural Gas and Natural Gas Reserves
• 90% of gas in natural gas is Methane
– Followed by propane, ethane, and butane
• Cleanest burning fuel
• Highest net energy value
• NG pipelines run throughout U.S.
– Abundant reserves
– NG is cooled and compressed until it becomes a liquid
(LNG) for transport
– LNG is used in rural U.S. areas
– Russia has more than 30% of known reserves
– Middle East has 36% of reserves
Unconventional Methane Stores
• Methane can be found frozen in ice as methane
hydrate
– Can be removed by dissolving the ice in methanol
– Methane in the ice sheets will be released with global
warming
• Methane found with coal deposits
– Close to surface, making extraction feasible
– Under groundwater which would need to be extracted
first.
– The water is contaminated with salts and minerals
– The withdrawal is drying local wells
– Livestock and wildlife are being killed by traffic and waste
left around the drill sites
Nuclear Power
• U.S. has nevfer had an accident where
significant amount of radiation was released
• Twice as expensive as coal
• 103 reactors in 31 states produce 20% of
nations electricity
• Obama has renewed interest in nuclear
Nuclear Fuel Enrichment
• U.S. has 22% of known Uranium reserves
– Australia has 26%
• Uranium must be mined
– Normally from sedimentary rock
– Mine tailings are radioactive
– Workers are susceptible to lung cancer from radon
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238U
(99.28% of ore); 235U (0.71%); 234U (0.01%)
235U is the desired isotope; so it is concentrated to 3%
or greater
Nuclear
• Pellets shape of pencil and roughly one-inch
long
– Placed in thin metal closed pipes ~12-16 feet long
called fuel rods; then clustered in groups of 100200 called fuel assemblies; 250 assemblies in
small reactor and 3,000 in large reactor
• Equivalent of one ton of coal or four barrels of
crude oil
Nuclear Fission
• Is the splitting of an atom to release energy and
particles
• In a reactor, neutron hits atom, splits atom into two
smaller nonfissionable nuclei, releasing energy and
more neutrons, continuing the reaction
• Fuel rods are replaced when spent
– 1/3rd at a time
• Moderators needed with the rapidly moving neutrons
attracted by 238U, 235U are more likely to be struck by
slow moving neutrons; so graphite, beryllium, H2O
(light water), or D20 (heavy water) is needed
• Moderators slow rapidly moving electrons, which
makes it more likely they will strike the 235U