Energy Part 2 – Fossil Fuels. Coal Types: Lignite – soft, lowest heat content Bituminous –...
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Transcript of Energy Part 2 – Fossil Fuels. Coal Types: Lignite – soft, lowest heat content Bituminous –...
Coal Types:
Lignite – soft, lowest heat content Bituminous – soft, high sulfur content, 50% of US reserves Anthracite – hard, high heat content, low sulfur, 2% of US
reserves
Coal
Supplies 25% of world energy China and the US consuming the most 87% of coal in the US is used to produce
electricity Clean Air Act: requires a 90% reduction of
sulfur-containing gases from coal combustion
Extraction and Purification of Coal Extraction methods:
Surface mining Underground mining
Purification Removes foreign materials Screens for size Crushes and washes coal to remove
contaminants May convert coal to liquid through clean coal
technologies
Clean Coal
Process to reduce the negative impacts on the environment from burning coal Washing coal to remove minerals and impurities Capturing sulfur and carbon dioxide from flue
gases Others:
using natural gas Microbial fuel cells charged with biomass or
sewage
Steps of Clean Coal Technology1. Oxygen is introduced to burn coal
completely2. Coal is pulverized to burn more completely3. Ash is removed using electrostatic
precipitators4. Steam is condensed and returned to the
boiler
5. CO2 is removed using live and then sequestered
Coal Reserves and Global Demand Coal is the world’s
largest sources of fuel used to produce electricity
US has largest reserve China is largest
producer Reserves expected to
last about 300 years
CoalPros Abundant, known reserves
(300 years worth) Unidentified reserves (1,000
years worth) US reserves will last 300 years Relatively high net-energy
yield US government subsidies
keep prices low Stable, non-explosive; not
harmful if spilled
Cons Extraction methods disrupt
environment and lead to pollution
Underground mining is dangerous and unhealthy
Up to 20% ends up as fly ash, boiler slag, sludge
Releases mercury, sulfur, and radioactive particles into the air
35% of CO2 pollution 30% of NOx pollution Expensive to process and
transport Pollution causes global
warming Pollution controls are
expensive
Energy Crisis Shortages of fuel in the world market
Mainly petroleum OPEC (Organization of Petroleum Exporting
Countries) Control world Petroleum supply OPEC decrease production to increase cost of oil
or increase production to decrease the cost of oil As prices for oil increase tar sands and oil
shale become profitable sources of oil
Sorry, your car is not running on dead dinosaurs Petrochemicals (derived from oil) are used for
manufacture of paint, drugs, plastics, etc. Natural Gas often found with oil deposits
Also with coral beds, shale, gas hydrates, and tight sands
Oil Extraction and Purification Extraction:
Drill down to the oil, usually trapped in porous sandstone
Oil under pressure flows out naturally Low pressure wells must be pumped
Purification: Crude oil is sent to a refinery and “cracked” Cracking = separating the components by boiling
point Produces: gasoline, heating oil, diesel oil, asphalt,
etc.
Natural Gas Extraction and Purification Extraction:
Usually present below non porous areas and above the oil
Extraction similar to oil extraction Flows from well under own pressure and pumped
into gas pipelines
560 billion m3 produced in the US each year
Methane Hydrates Methane locked in ice
Located in permafrost regions At water depths greater than 1,640 feet (500m)
Natural gas uses expected to increase Natural gas is clean burning Natural gas plants are relatively cheap to build
US Natural gas consumption is expected to increase 40% Due to use in transportation Alternative liquid fuel
Oil Shale Contains kerogen
Heating oil shale in the absence of air turns kerogen into oil
3 trillion barrels of recoverable oil from oil shale in the world 750 billion located in the United States
Largest reserves: Estonia, Australia, Germany, Israel, Jordan In US Wyoming, Utah, Colorado
Oil Shale Mining In suti – heat oil shale in the ground to extract
oil and gas via pumping Potential to affect aquifers
Surface Mining Destroys environment Moderate net energy yield due to high inputs
required to extract oil and repair environment
Tar Sands Contain Bitumen – semisolid form of oil
High in sulfur (~5%) = dirty oil Represent about 2/3 of world oil reserves Most in Canada and Venezuela
Keystone Pipeline Moderate net-energy yield due to high inputs
Strip-mining In suti recovery
Hydrofracking Removes natural gas that was previously
urecoverable Process:
Chemicals are mixed with large quantities of water and sand
Mixture is injected into wells at extremely high pressure to create fractures in rock
Oil and natural gas to flow out of the well Estimates 80% of natural gas wells will be
with hydraulic fracking
HydrofrackingPros Process of bringing well to
completion is short Well can be in production
20 – 40 years Makes it possible to access
new reserves of oil and natural gas
Stimulates the economy Allows independence from
foreign sources of oil
Cons Dangerous chemicals used
in the process can enter the water supply
Toxic, radioactive, caustic liquids pose storage problems
Currently no regulations for fracking
Results in contaminated water, air pollution, destroyed streams, and negative environmental impacts
Oil World Reserves and Demand 45% - 70% of world’s
reserves already depleted
About 50 year supply left
Competition between emerging economies
2/3 of oil in US is used in transportation
1/4 of oil used in industry
Natural Gas World Reserves and Demand US has an estimated
75 year supply
34% in Middle East 40% in Russia and
Kazakhstan 3% in US
Oil Pros Inexpensive (prices
increasing) Easily transported through
pipes, etc. High net-energy Ample supply – short term Large US government
subsidies in place Versatile – used in
manufacturing many products
Cons Limited reserves are
declining Produces pollution Causes land disturbances
through drilling Oil spills on land and ocean
contaminate the environment
Disrupts wildlife habitat Supplies are volitile
Natural GasPros Pipelines and distribution
networks are in place Easy to transport Relatively inexpensive Estimated 125 year reserve Less pollution than other
fossil fuels Extraction leads to less
environmental damage
Cons H2S and SO2 released in
process LNG is expensive and
dangerous Lower net-energy Leakage of CH4 has more
impact on global warming than CO2
Disruption to collection areas
Extraction leads to waste water
Land subsidence
Synfuels Any fuels produced from coal, natural gas, or
biomass through chemical conversion
Creates substances the same as crude oil or processed fuel
Eg: SNG – synthetic natural gas created through coal liquification
Synfuel Pros and ConsPros Easily transported
through pipelines Produces less air
pollution Large supply of raw
materials are available Can produce gas,
diesel, or kerosene without reforming or cracking
Cons Low net energy Plants to build are
expensive Would increase
depletion of coal due to inefficiencies
Product is more expensive than petroleum
Case StudiesArctic National Wildlife
Refuge (ANWR): ANWR in NW Alaska
(19 million acres) Drilling debate since
1977 Controversy:
economics of oil recovery compared to environmental damage
Keystone Pipeline System Transport synthetic
crude and diluted bitumen from Canadian oil sands to refineries in Illinois, distribution hubs in Oklahoma, Texas ports
Continuing debate over costs and benefits to US economy and environment