RENEWABLE ENERGY SOURCES

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RENEWABLE ENERGY SOURCES

• Our power, our future

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Residential Solar Power

• Using the sun to heat your home

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Photovoltaics

• In PV cells, suns energy powers a chemical
  reaction -gt electricity
• Commercial residential PV modules anywhere from
  10 to 300 watts
• Can be used en masse to create power plants
• Direct current generated must be inverted into
  alternating current energy

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Pollution Reduction

• Over 20 years, a 100-megawatt plant avoids 3
  million tons of carbon dioxide.
• 1000 kWh of solar power saves
• 8 pounds of sulfur dioxide
• 5 pounds of nitrogen oxide
• 1,400 pounds of carbon dioxide

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Expensive!

• 5-kW systems can cost up to 40,000!
• Power costs up to 9/watt!
• Over 30 states offer incentives
• California is the leader in encouraging solar
  power use

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Biomass Fuels
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Solid Fuel Combustion

• Combustion of biomass instead of coal tends to be
  cleaner and helps eliminate waste efficiently
• Products burned are usually wood matter,
  vegetation, waste from lumber yards, etc
  (cellulosic)

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Digestion

• Occurs naturally - bacteria feed on decomposing
  waste
• Releases gases like methane, hydrogen, CO, etc
• Pipelines running thru waste collect gases
  (landfills, feedlots, zoos)
• Synthesis gases can become any kind of
  hydrocarbon fuel.

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Pyrolysis

• Intense heat (above 800 F) and pressure makes a
  product like charcoal, doubling the energy
  density
• Highly transportable and efficient

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Ethanol

• A.k.a. alcohol chemical formula CH3CH2OH.
• Produced using the dry mill method.
• 81 plants in 20 states can produce 4.4 billion
  gallons each year
• Any cellulosic biomass can be converted into
  ethanol.

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Ethanol in Cars

• Mixed with gasoline to form either E10 or E85
• Number is percentage of ethanol in mixture
• Increases octane rating and decreases emissions
• Ethanol is favored oxygenate under Clean Air Acts
  Amendments of 1990
• Many incentives encourage its use

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Wind Energy

• Fastest Growing Source of Renewable Energy

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History and Definition

• First use as early as 5000 B.C.
• First used to generate electricity in Denmark as
  early as 1890.
• Now, wind-generated electricity is very close in
  cost to the power from conventional utility
  generation in some locations.

• Wind is a form of solar energy.
• Caused by uneven heating of atmosphere by the
  Sun, irregularities of the Earths surface, and
  rotation of the Earth.
• The amount and speed of wind depends on the
  Earths terrain and other factors.

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Horizontal-Axis Wind Turbine
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Vertical-Axis Wind Turbine
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Advantages and Disadvantages

• Wind is free, wind farms need no fuel.
• Produces no waste or greenhouse gases.
• The land beneath can usually still be used for
  farming.
• Wind farms can be tourist attractions.
• A good method of supplying energy to remote
  areas.

• Not always predictable.
• Price of land.
• Changing landscape.
• Can kill birds - migrating flocks tend to like
  strong winds.
• Can affect television reception if you live
  nearby.
• Noisy. A wind generator makes a constant, low,
  "swooshing" noise day and night.

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Hydroelectric Power

• Americas leading renewable energy source

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History and Basics

• The earliest reference from 4th century BC Greek
  literature. hydro comes from the Greek word for
  water.
• By 1980, accounted for 25 of global electricity
  and 5 of total world energy use, totalling 2,044
  billion kilowatt hours (kW h).

• Water flows from a high potential energy (high
  ground) to lower potential energy (lower ground),
  the potential energy difference is partially
  converted into electric energy through the use of
  a generator.
• There are two major designs in use that utilize
  water to produce electricity

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Hydroelectric Dam

• Advantages
• The energy is virtually free.
• No waste or pollution
• Reliable
• Can cope with peaks in demand.
• Can increase to full power very quickly, unlike
  other power stations.
• Electricity can be generated constantly.

• Disadvantages
• Expensive to build.
• Environmental concerns upstream and downstream
• Siting

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Pumped-Storage Plant

• Advantages
• Without some means of storing energy for quick
  release, we'd be in trouble.
• Little effect on the landscape.
• No pollution or waste.
• Disadvantages
• Expensive to build.
• Once it's used, you can't use it again until
  you've pumped the water back up. Good planning
  can get around this problem.
• Important Concept
• These plants are not really power stations, but a
  means of storing energy from other power
  stations.

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Ocean Energies

• Waves, tides, ocean currents, ocean thermal energy

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General Information

• 70 of Earths surface is covered by oceans
• Huge potential a mere .1 of total energy
  potential in oceans would satisfy all of
  mankinds energy needs five times over.
• United States faces siting challenges and
  economic obstacles
• Europe leader in ocean energies
• Exploiting Location and natural geography
• Winds blown across Atlantic (West -gt East)
• create bigger waves -gt more energy potential
• Areas for underwater currents and tides

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Wave Power vs. Ocean Currents

• Waves push high-pressure oil through hydraulic
  motors to generate electricity fed to grid via
  underwater cable
• Wave farms 30 MW / sq. km enough to power
  20,000 homes
• All systems manipulate wave motions to power
  hydraulic pumps or spin turbines
• European power costs roughly 9 cents/kWh

• Britains example
• Turbines anchored to ocean floor, currents spin
  blades, generate electricity.
• More efficient than wind 8 mph ocean current
  vs. 230 mph wind
• 10 cents/kWh estimate
• Verdant Power company plans to build 5-10 MW
  field in East River in New York

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Tidal Power

• Damming estuaries, water flows through turbines
• One method ebb generation
• High and low tides are very predictable
• Can only produce electricity at certain times
• Not many places in the world where its efficient
• 5-10 meter difference between high and low tides
• High costs to build deters private investors
• Negative impact on estuarine ecosystems

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Ocean Thermal Energy Conversion (OTEC)

• Hawaii can exploit this technology because of its
  location near the equator
• Sun heats water to depths of 100 meters to
  temperatures around 24-30 degrees Celsius
• Flashing into steam
• Cold water from deeper in ocean condenses the
  steam, produces desalinated water!
• OTEC can serve much of Hawaiis energy needs, but
  not really any of the contiguous United States

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Geothermal

• Exploiting Earths temperatures to produce
  electricity and heat our homes.

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Direct Heating vs Generating Electricity

• Immediate, usable energy
• Can heat buildings or entire areas
• Relatively warm air in winter
• Warm water piped under streets in Klamath Falls,
  OR melts snow
• Same principle of relative temperatures allows
  for cooling of buildings in summer

• Different types of plants depending on geothermal
  area
• Hot water/steam
• Not-so-hot water
• Using steam directly to spin turbine
• Flashing steam to spin turbine

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Advantages

• Reliability the Earths heat provides a
  constant source of energy
• Low impact on environment
• Room for improvement 2,300 MW in 2004, D.O.E.
  estimates could be 15,000 MW by 2014
• Hot Dry Rock
• How does it work?
• If the technology works, we could tap geothermal
  energy ANYWHERE!

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Disadvantages

• Depletion of water
• Re-injecting water
• Earthquakesshould plants be responsible?
• Heat depletion
• Natural cooling of Earths crust cannot be
  avoided
• Plants become less and less efficient
• Economics
• Building costs 1175-1750 per kW installed
  capacity
• Geothermal areas arent always near electricity
  grids

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Projections for Geothermal

• National Commission on Energy Policy estimates
  4-6 cents per kWh
• Compares favorably with other renewables (solar
  20-25 cents per kWh)
• Compares favorably with coal and NG 4-5 cents
  per kWh
• Estimates depend on availability of geothermal
  resources and success of HDR technology

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Encouraging Development Through Government
Policies

• Energy Policy Act of 2005, Tradable Permits,
  State Renewable Portfolio Standards (RPS)

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National Level

• Congress passed Energy Policy Act of 2005
• To expand renewables so they become economically
  competitive energy sources
• Increase US consumption of renewable energy
• At least 3 from 2007-09
• Developing existing renewable sources
• Hydroelectric 10,000,000 budget for incentives
  to plants
• Up to 750,000 to any particular plant
• Goal increase efficiency by at least 3
• Biomass synergy between forest-clearing and
  biomass facilities expand markets for products
  of forest clearing
• National Commission on Energy Policy
• Tradable permits system

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State Level

• State Renewable Portfolio Standards (RPS)
• AZ, CA, CO, CT, IA, ME, MD, MA, NJ, NM, NY, NV,
  PA, RI, TX, WI
• States with ample renewable resources
• Hawaii, Illinois, Minnesota shifting towards
  adopting them
• Most have adopted them in the past five years,
  more will catch on as conventional energy sources
  run out.

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The Future

• Energy Policy Act means we will see more
  renewables in the next ten years efficiency will
  increase
• Tradable-permits system, if passed, will provide
  huge economic boost to renewables
• consumption of renewables will increase by up to
  60
• depends on solving problems of initial allocation
  of permits, and other countries cooperation
• Action at the state level will increase as the
  nation seeks to find alternatives to fossil fuels
• More renewables legislation will undoubtedly be
  put into effect as we run out of energy