2/6/2015 1 Nonrenewable Energy Resources February 6, 2015 Mr. Alvarez Nonrenewable Energy Nonrenewable Energy- fossil fuels (coal, oil, natural gas) and nuclear fuels. Energy Use Commercial energy sources- those that are bought and sold, such as coal, oil and natural gas. Subsistence energy sources- those gathered by individuals for their own use such as wood, charcoal and animal waste.
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Nonrenewable Energy Resources 12- Nonrenewable... · (not a coal) Lignite (brown coal) Bituminous (soft coal) Anthracite (hard coal) ... Advantages and Disadvantages of Coal . 2/6/2015
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Easy to exploit by surface mining Trace metals like mercury, lead, and arsenic are found in coal
Technological demands are small Combustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere.
Economic costs are low Ash is left behind
Easy to handle and transport Carbon is released into the atmosphere which contributes to climate change
Needs little refining
Advantages and Disadvantages of Coal
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Oil/Gas Formation
• Oil & Natural Gas form from trillions of algae, phytoplankton and bacteria.
Oil/Gas Deposit Structure:
Hydrocarbons:
• The longer the chain, the more stable the molecule is
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•Crude oil (a.k.a. petroleum) is boiled during fractionating to separate different compounds.
• The longer the hydrocarbon chain, the higher the boiling point.
Fractioning Column
Unconventional Oil • Bitumen (tar or pitch)- a degraded type of
petroleum that forms when a petroleum migrates close to the surface, where bacteria metabolize some of the light hydrocarbons and others evaporate.
• Oil sands- slow-flowing, viscous deposits of bitumen mixed with sand, water, and clay.
• Despite the gulf oil spill, deepwater drilling has been relatively safe over many years.
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Environmental Impacts of Oil Drilling
• Construction of drilling rigs causes Surface disturbance & disruption of ecosystems.
• Spills and leaks from rigs or pipelines/tankers that are transporting oil.
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Advantages and Disadvantages of Petroleum
Advantages Disadvantages
Convenient to transport and use Releases carbon dioxide into atmosphere
Relatively energy-dense Possibility of leaks when extracted and transported
Cleaner-burning than coal
Releases sulfur, mercury, lead, and arsenic into the atmosphere when burned
Natural Gas • Natural gas- exists as a component of
petroleum in the ground as well as in gaseous deposits separate from petroleum.
• Contains 80 to 95 percent methane and 5 to 20 percent ethane, propane, and butane.
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Advantages/Disadvantages of Natural Gas
Advantages Disadvantages
Contains fewer impurities and therefore emits almost no sulfur dioxide or particulates
When unburned, methane escapes into the atmosphere
Emits only 60% as much carbon dioxide as coal
Exploration of natural gas has the potential of contaminating groundwater
The Hubbert Curve
Hubbert curve- a graph that shows the point at which world oil production would reach a maximum and the point at which we would run out of oil.
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The Future of Fossil Fuels
• If current global use continues, we will run out of conventional oil in less than 40 years.
• Coal supplies will last for at least 200 years, and probably much longer.
• Fission- a nuclear reaction in which a neutron strikes a relatively large atomic nucleus, which then splits into two or more parts.
Nuclear Energy
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How Do Nuclear Reactors Work
• Most commonly used fuel is U235, a naturally occurring radioactive isotope of uranium. – Occurs naturally at 0.7% of uranium, but must be
enriched to about of 3% to create a fuel pellet.
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Nuclear Reactors
• Nuclear power plants work by using heat from nuclear fission to heat water. This water produces the steam to turn the turbine, which turns a generator.
• Fuel rods- the cylindrical tubes that house the nuclear fuel used in a nuclear power plant.
• Control rods- cylindrical devices that can be inserted between the fuel rods to absorb excess neutrons, thus slowing or stopping the fission reaction.
Nuclear Reactors
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Controlling the Chain Reaction
Control rods
Fuel
Assemblies
Withdraw control rods,
reaction increases
Insert control rods,
reaction decreases
“Heavy
Water” as
mediator
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Pressurized Water Reactors (PWR)
• Seventy percent of nuclear power plants are pressurized water reactors.
• Water is circulated in a separate line through the core to absorb heat from fuel rods.
• Pumped to steam generator where it heats a secondary loop.
• Steam from secondary loop drives high-speed turbine producing electricity.
Summary: How Nuclear Energy Works
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• Each atom of U-235 produces 3 neutrons
–one starts next reaction
–two can convert U-238 to Pu-239
–More energy can be created than used (breeding)
• Breeder reactors can greatly extend the lifetime of resource availability but increase the damage in case of disaster
– Waste materials that contain sufficiently low concentrations or quantities of radioactivity so as not to present a significant environment hazard if properly handled
– Contaminated clothing rags, tools, etc.
• High-Level Radioactive Waste – Extremely toxic nuclear waste, such as spent fuel
elements from commercial reactors.
– How do we dispose of this waste material?
Dealing with Nuclear Waste: Options
• Undergound burial
• Disposal in space
• Burial in ice sheets
• Dumping into subduction zones
• Burial in ocean mud
• Conversion into harmless materials
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• Warm water is returned to the environment (thermal pollution)
• Fish get ground up in entry pipes
• Manatees love to stay over-winter in the warm water!
COOLENT WATER
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Comparing Coal & Nuclear: IMPACTS
Nuclear Power Plant Accidents • Three Mile Island (1979)
– Pennsylvania
– The most serious US accident
• Chernobyl (1986) – Worst accident in the history of
commercial nuclear power
– Because of this, it is theorized that in the next 20 to 30 years, there will be an increase in cancer in northern Europe.
• Fukushima (2010) – Earthquake Tsunami
Damage to reactor cooling system leaking radioactive water
– Unknown effects on humans & ecosystems
Advantages Disadvantages
No air pollution is produced Possibility of accidents