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RENEWABLE ENERGY SOURCES. Our power, our future. Residential Solar Power. Using the sun to heat your home. Photovoltaics. In PV cells, sun’s energy powers a chemical reaction -> electricity Commercial residential PV modules anywhere from 10 to 300 watts

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renewable energy sources


Our power, our future

residential solar power

Residential Solar Power

Using the sun to heat your home

  • In PV cells, sun’s energy powers a chemical reaction -> 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
pollution reduction
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
  • 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
solid fuel combustion
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)
  • 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.
  • Intense heat (above 800° F) and pressure makes a product like charcoal, doubling the energy density
  • Highly transportable and efficient
  • 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.
ethanol in cars
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
wind energy

Wind Energy

Fastest Growing Source of Renewable Energy

history and definition
History and Definition
  • Wind is a form of solar energy.
  • Caused by uneven heating of atmosphere by the Sun, irregularities of the Earth’s surface, and rotation of the Earth.
  • The amount and speed of wind depends on the Earth’s terrain and other factors.
  • 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.
advantages and disadvantages
Advantages and Disadvantages
  • 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.
  • 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.
hydroelectric power

Hydroelectric Power

America’s leading renewable energy source

history and basics
History and Basics
  • 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
  • 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).
hydroelectric dam
Hydroelectric Dam
  • Disadvantages:
    • Expensive to build.
    • Environmental concerns upstream and downstream
    • Siting
  • 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.
pumped storage plant
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.
ocean energies

Ocean Energies

Waves, tides, ocean currents, ocean thermal energy

general information
General Information
  • 70% of Earth’s surface is covered by oceans
  • Huge potential: “a mere .1% of total energy potential in oceans would satisfy all of mankind’s 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 -> East)

create bigger waves -> more energy potential

    • Areas for underwater currents and tides
wave power vs ocean currents
Wave Power vs. Ocean Currents
  • Britain’s 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
  • 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
tidal power
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 it’s efficient
    • 5-10 meter difference between high and low tides
  • High costs to build deters private investors
  • Negative impact on estuarine ecosystems
ocean thermal energy conversion otec
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 Hawaii’s energy needs, but not really any of the contiguous United States


Exploiting Earth’s temperatures to produce electricity and heat our homes.

direct heating vs generating electricity
Direct Heating vs Generating Electricity
  • 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
  • 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
  • Reliability – the Earth’s 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!
  • Depletion of water
    • Re-injecting water
    • Earthquakes…should plants be responsible?
  • Heat depletion
    • Natural cooling of Earth’s crust cannot be avoided
    • Plants become less and less efficient
  • Economics
    • Building costs: $1175-1750 per kW installed capacity
    • Geothermal areas aren’t always near electricity grids…
projections for geothermal
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
encouraging development through government policies

Encouraging Development Through Government Policies

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

national level
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
state level
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.
the future
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