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26 Cards in this Set
- Front
- Back
Renewable Energy Resources
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1) No one resource will provide all our energy needs
2) each has advantages and disadvantages variety of renewable resources |
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Alternative energy Advantages
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1) Renewable & abundant
2) Produce little pollution 3) low maintenance 4) Safe |
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Alternative Energy Disadvantages
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1) Technology still being developed
2) Expensive 3) infrastructure compatibility 4) acceptance by society |
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Solar
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Solar Farms use mirrors to focus/reflect sunlight onto a reciever
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solar electricity
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Photovoltaics
Sunlight strikes a semiconductor, knocking electrons free that flow as current effeciently improving 2008 PV cells now 42.8% efficient commercial cells at 14-19% |
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photovoltaic
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method of generating electrical power by converting solar radiation into direct current electricity
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Solar advantages
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1) Widely available on a long timescale
Energy Payback (EPB) time it takes to generate enough energy to offset the energy used in system production 2) since 200 solar EPB has dropped 2-3 years |
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Solar Disadvantages
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1) Insolation Variations
- latitude, season, time of day, weather etc - need battery backups 2) generates DC current only 3) some pollution from making PV cells 4) room to build solar farms |
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Hydroelectricity
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Flowing water used to turn turbines that generate electricity
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Hydroelectricity advantages
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1- Widely available
2- Doesn’t pollute the water 3- Quick profit 5 years to recover construction costs via sales of electricity |
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Hydroelectricity Disadvantages
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1) Reservoir creating flood areas
2) Dams alter downstream environments 3) we've already used best sites 4) Fear about dam failure |
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Case study: banqiao Dam
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Built to resist a 1000 yr flood event
Aug 1975: 2000 yr flood event 41in rain fell in 24hrs (full years worth of rain in 1 day) 700 million tons of H20 released in 6hrs 171,000 died |
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New Buoy system
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convert kinetic energy into electricity
New Buoy system is 2 components: 1) stationary centerpiece with copper coils 2) float containing a magnet |
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Buoy system advantages
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Simple device, consistent
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Buoy system Disadvantages
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1) rough Environment
storm damage/loss, salt water corrosion, marine life 2) Changes coastal environments reduce wave energy 3)Some areas far from coasts 4) effects on wildlife anchor line vibrations = noise pollution Electro- magnetic fields disrupt wildlife |
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Wind Power
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Winds generate 5x more power than total global energy consumption
N dakota could provide 1/3 of US electrical needs 2008 wind generates 1.5% of global electrical supply |
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Wind Advantages
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1) Cost down 80% in last 20 years
2) Energy payback only 1year 3) safe for birds |
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Wind Disadvantages
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1)Not consistent in many areas
2) Few places currently make the equipment 3) best sites often far from population centers 4) Not in my backyard |
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WARP Turbines
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Wind Amplified Rotor Platform
More attractive tower design focus winds into smaller area and accelerate it faster = more energy produced |
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Geothermal Advatages
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more consistent than wind, solar or hydro
provides < 1% global needs can circulate water through pipes to draw heat GT heat pumps: Temp below ground is more constant than at the surface Heat water enough and you generate steam to run turbines |
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Geothermal Disadvantages
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1) geothermal gradient varies
2) Fluids can contain unsafe/corrosive dissolved substances 3) Much heat energy lost during movement of fluids/steam 4) subsidence (when using groundwater) 5) can be depleted if poorly managed |
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Biofuels
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Use of Bilogical materials as fuel
Renewable if managed properly |
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Ethanol Advantages
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Starch from crops fermented to produce alcohol
1) mix with regular gas to reduce pollution and amount of gas needed 2) Big new source of income for farmers |
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Ethanol Disadvantages
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1)Not yet cost effective without government subsidies
2) takes a lot of energy to produce 3) Ethics, growing fuel instead of food |
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Algae Advantages
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Grow algae then convert their lipids into biofuel
algae farms = oil crop 1) doesn't need freshwater 2) doesn't need cropland/soil 3) waste is biodegradable 4) multiple harvests per year |
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Algae disadvantages
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1) doesn't lower atmospheric CO2 levels as some claim
2) currently expensive 3) production estimates vary a lot theory produce 150,000 gal/acre/year reality you get 33,000 gal/acre/year |