Chp 18 “Renewable Energy Sources”.ppt

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					              Chapter 18
Renewable Energy Sources
Sources of renewable energy
   Solar
       Direct solar energy
       Biomass/biofuels
       Wind
       Hydro-electric
   Geothermal
   Tidal
Electrical Generation Costs
Direct Solar Energy

   Energy directly from the sun
   Tremendous amount
   Always available
   Must be collected
Active Solar Heating
   Collectors absorb solar energy
   Pumps or fans distribute heat
   Primarily for heating water
    Passive Solar Heating

   No mechanical devices to distribute
    heat
   New home design
   Room temperature
    is steady
   Convection
   Save on heating!
Photovoltaic (PV) Solar Cells


   Convert sunlight into electricity
   Thin wafers or films
   No pollution
   Minimal maintenance
Photovoltaic (PV) Solar Cells
   Can be used in remote areas
   Good choice for developing
    countries: why?
   School, home use
   Can look like conventional roofing
   Prices are coming down but future
    progress is critical
    Solar Thermal Electric Generation


   Sun’s energy concentrated by mirrors, lenses
   Heat a working fluid
   Fluid is circulated to boil water
   Steam generates electricity
Hydrogen As A Fuel Source
   Could be the fuel of the future
   Where does the hydrogen come from?
       Electrolysis
   Must use renewable fuel source to obtain the hydrogen!
   Few pollutants produced when burned
   Can be used for transportation
Solar-Generated Hydrogen
   Use PV cells for electrolysis of water
   Currently not very efficient
   Still expensive
   Would need new distribution system for transportation
   Future development is critical
Solar-Generated Hydrogen
   Fuel cells
       Electrochemical cell
       Like a battery
       Major carmakers working on it
Indirect Solar Energy
   Indirect use of sun’s energy
   Biomass, wind power, hydroelectricity
    Biomass Energy


   Wood, plants, animal wastes
   Potentially renewable: why?
   Burned to release energy
   Half of human population
    relies on
   Cooking, heating
Biogas

   Mixture of gases
   Similar to natural gas
   Animal wastes
   Biogas digesters
       Decompose wastes
       Use gas for cooking, lighting
       Solid remains are fertilizer
   Can also be used to power fuel cells
Biomass As A Liquid Fuel
   Methanol, ethanol
   Gasohol: mix gasoline and ethanol
   Biodiesel
       Plant, animal oils (sometimes waste products)
       Becoming more popular
       Burns cleaner than regular diesel
Ethanol
   Sugarcane, corn, wood, agricultural and municipal wastes
   Government subsidizes
   Good outlet for some wastes
   Problems
       Land and water use
       Soil erosion
       Decreased food production
Wind Energy

   Fastest growing
     energy source
   No waste, emissions
   Electricity
   Costs are declining
   Denmark is a world
    leader
   Need steady winds
   Great Plains of U.S.
Wind Energy Problems

   Birds and bats killed by turbines
       Avoid migration routes
       Operate only at certain times
       Monitor the project
   Visual pollution
       Often on ridge tops or out in open
        fields, water where they are highly
        visible
       Some people feel they obstruct
        pretty views
    Hydropower

   Flowing or falling water spins
    turbines
   Most efficient way to
    produce electricity
   19% world’s electricity
   2200 U.S. plants
    Hydropower Problems
   Damages ecosystem, species
   Reduces downstream flow
   Reservoirs eventually fill in
   Danger of collapse
   Degrades river
   Increase in waterborne
    disease: schistosomiasis
Geothermal Energy
   Use energy from Earth’s interior
   Big potential source
   Electricity
       Hydrothermal reservoir: hot fluid
       Bring fluid to surface to generate electricity
   Emits very few pollutants
   Is it truly renewable?
   Land may subside
Geothermal Heat Pumps
   Used for heating and cooling
   Ground temperature relatively constant
   Underground pipes carry water
   Fluids circulate or “pump and dump ground water”
   Can be expensive to install
   Very efficient!
Tidal Energy
   Use power of the tides to generate electricity
   France, Russia, China, Canada
   Very few ideal locations
   May be damaging to ecosystems
Conservation & Efficiency
   Energy conservation
       Using less energy
       Reduce use, waste
       Carpooling
   Energy efficiency
       Using less energy for a task
       More fuel-efficient cars
   Both very important!
Energy Consumption Trends


   Use is on the increase
   Greatest increase in developing countries: why?
Energy-Efficient Technologies
   Appliances, automobiles, light bulbs, furnaces, etc…
   “Superinsulated” buildings
   May cost more, but will save money!
Cogeneration
   Combined heat and power (CHP)
   Recycling “waste” heat
   Generate electricity, use steam before cooling it back
    down
Energy Conservation At Home
   Average household: $1500/year on utilities
   Use energy-efficient technologies
   Better insulation, windows
   Seal cracks
   Replace inefficient appliances
Energy Conservation At Home
Case Study: Green Architecture
    Adam Joseph Lewis Center for Environmental Studies,
     Oberlin College
    Geothermal heat pump
    PV cells for electricity
    Triple-paned windows
    Motion sensors for light switches
    Recycle wastewater
    Sustainable wood
    Recycled carpet
Course overview
   Environmental challenges and sustainability
   Climate change
   Ecosystems and their services
   Natural resources
       Freshwater and oceans
       Land resources (forests, rangelands, etc.)
       Agriculture
       Biodiversity
       Energy
           Nonrenewable
           Renewable
Course overview – major focus of Final
   Environmental challenges and sustainability
   Climate change
   Ecosystems and their services
   Natural resources
       Freshwater and oceans
       Land resources (forests, rangelands, etc.)
       Agriculture
       Biodiversity
       Energy
           Nonrenewable
           Renewable
   Plus major concepts from throughout semester

				
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