nonrenewable energy resources. oil origin:dead organic matter subjected to high pressure & high...
TRANSCRIPT
Nonrenewable Energy Resources
Oil
Origin:dead organic matter subjected to high pressure & high temperatureMostly hydrocarbonsMost highly used energy
source in developed countries
Oil Recovery
Primary oil recoverySecondary oil recoveryTertiary oil recovery
Oil ProcessingMost crude oil is transported by pipeline to a refineryDistillation is used to separate components From heaviest to lightest
Oil Reserves
13 countries of OPEC (organization of petroleum exporting countries) have 67% of world’s reserves
Pros of Conventional Oil
CheapEasily transportedEasily extractedHigh net energy yield
Cons of Conventional OilCheap prices have: Encouraged countries to become
dependent on oil Encouraged waste Discouraged improvements in
efficiency Discouraged switching to other energy
sources
PollutionEnvironmental degradation
Shale OilOil shale contains kerogen (a mixture of hydrocarbon compounds)Removed by surface or subsurface miningShale: crushed & heated to vaporize the kerogenKerogen sent by pipeline to refineryProcessed to remove impurities
Cons of Shale OilLower net energy yield than conventional oil Requires lots of waterSurface mines destroy the environmentWater pollution due to leaching from processed shaleSubsurface mining is cost prohibitive
Tar Sand
Mixture of clay, sand, water, & bitumen (a high-sulfur heavy oil)Removed by surface miningHeated with steam which floats bitumen to the topBitumen purified into a synthetic fuelLargest deposits are in Alberta, Canada
Cons of Using Heavy Oil from Tar Sand
Low net energy yield Requires lots of waterReleases lots of air pollutantsProcessing plants create huge waste disposal ponds
Natural Gas50-90% methane, other hydrocarbons & H2SConventional N.G. lies on top of crude oilUnconventional N.G. is found in coal beds, shale rock, underground sands & gas hydrates & have promise in the future because of their abundance
World’s Natural Gas Supplies
U.S. surpassing Russia as largest natural gas producer (fracking)
Pros of Natural GasCheaper than oilHigh net energy yieldBurns hot with less pollution than other fossil fuelsExtraction damages the environment less than extracting coal or uraniumEasy to processCan be used to power vehicles & in fuel cells
Cons of Natural Gas
Some H2S & SO2 can be released during processingMust be converted to liquid form before it can be shipped by tankerConversion is expensive & dangerous & reduces useful net energy yield by ¼Leaks of natural gas contribute to global warning(CH4)FrackingTed Talk: Fracking
CoalIs a solid, rocklike fossil fuelMostly carbon, some water, & sulfurThree types: Lignite—brown coal, low heat & sulfur
content, limited supplies Bituminous—soft coal, most commonly
used, high heat content, large supplies, high sulfur
Anthracite—hard coal, high heat content, takes longest to form, expensive, low sulfur
Coal ExtractionStrip mining Surface mining in which overlying layer
of soil & rock stripped off to reach coal Most common method of extraction Environmentally destructive, rain &
spoil produces sulfuric acidwater pollution
Subsurface mining 40% of U.S. mining Dangerousaccidents, black lung Labor intensive Acid drainage, land subsidence
Mountaintop Removal
http://www.youtube.com/watch?v=ZDAFQjLoxCM
How Is Coal Used?
Use of Coal to Generate Energy
Pulverized coal is burned at high temperaturesSteel pipes containing water run through the fire producing high pressure steamSteam turns a turbineTurbine spins a generator to produce electricity
Coal Supplies
66% of reserves are in the U.S., former Soviet Union, & China
Pros & Cons of CoalPros Abundant High net energy yield
Cons Environmental effects of extraction
(erosion, air pollution, water pollution) Extraction is dangerous Dirtiest fossil fuel to burn Expensive to transport
Nuclear Energy
Currently 24% of electricity in U.S.Energy created through a controlled nuclear reaction which boils water to power a generatorFuel is nonrenewable & dangerous wastes are created
Nuclear Fission Reactors
Split nuclei of atoms of U-235 to release energy in the form of high-energy heatHeat is used to make high-pressure steamSteam spins turbines to generate electricity
Light Water Reactor Parts
Core containing fuel rods packed with uranium pelletsControl rods which are moved in & out of the core to regulate the rate of fission Moderator keeps chain reaction going (can be water, graphite, or heavy water)Coolant (usually water) circulates through the core to remove heat & produce steam for generation of electricity
Advantages of Nuclear Power
No emission of air pollutants1/6 the CO2 of coal-generated electricityWater pollution & land disruption are low to moderateMany safeguards in place to prevent accidents
Cons of Nuclear Power
Radioactive wastes/spent fuel Can be reprocessed or stored long term
(for between 10,000 to 240,000 years) Fuel rods stored in pools of water on site
No underground storage facilities have ever been builtAfter 15 to 40 years of operation nuclear plants must be decommissioned
Safety of Nuclear Power Plants
1979 Three Mile Island Partial loss of reactor coolant 50% of core melted & fell to the
bottom of the reactor Unknown amounts of radiation escaped
NRC estimates a 15-45% chance of a complete meltdown at a U.S. reactor in the next 20 years
What Do We Do With Low-Level Radioactive Waste?
Must be stored 100-500 yearsBetween 1940-1970 most was put into steel drums & dumped into the oceanSince 1970 they have been buried in government-run landfills
What Should We Do With High-Level Radioactive Waste?
Must be stored for thousands of yearsProposals: Bury it underground in earthquake
resistant & waterproof areas Shoot it into space or into the sun Bury it under the Antarctic ice sheet or
Greenland ice cap Dump it into descending subduction
zones in the deep ocean Change it into harmless, or less
harmful, isotopes
Contaminated Radioactive Sites in the U.S.
45,000 existWill cost at least $230 billion & 75 years to clean up
What Can Be Done With Worn-Out Nuclear Plants?
Three methods proposed: Immediate dismantling Mothballing for 30-100 years & then
dismantling entombment
Nuclear Reactors & the Spread of Nuclear Weapons
Today the U.S. & 14 other countries sell nuclear power technology in the international marketplaceWe live in a world with enough nuclear weapons to kill everyone on earth 40 times
A Sustainable Energy Future for the U.S.
Need individual actionGovernment action: Increase fuel efficiency standards for
vehicles Establish energy-efficiency standards
for buildings & appliances Increase government sponsored R and
D Give tax credits & rebates Tax energy
A Sustainable Energy Future for the U.S.—cont.
Rely on more renewable energy Provide subsidies & tax credits Increase R and D
Reduce pollution & health risk Cut coal use Phase out coal subsidies Levy taxes on coal & oil use Phase out nuclear power & nuclear
power subsidies