Ch. 18 Renewable resources!!
Renewable energy – energy from sources that are constantly being formed
• Solar - sun• Hydroelectric – moving water• Wind• Biomass – organic material• Geothermal – Earth’s heat• Tidal - waves
Solar Energy - energy from the sun
• Nuclear Fusion creates energy on the sun– Only a fraction of this reached the Earth– But, this is enough to power:
• The wind (wind power)• Plant growth (biomass)• The water cycle (hydroelectricity)
• Nearly all renewable energy sources come from the sun!!!
Passive Solar – using the sun to heat something directly (ex: through windows)
Active Solar – collecting the suns energy to heat buildings or water (ex: solar cells or panels)
• Energy production from solar has doubled every 4 years since 1985!!
http://videos.howstuffworks.com/science-channel/5015-invention-nation-solar-panels-video.htm
http://solarsc.net/video/examples/how-solar-panels-work.html
Costs of Solar Energy
• All costs are up front costs, then savings follow– Solar pool heater - $3000 - $4000– Home solar water heater $1000 - $3500 (includes installation)– 1 kW power system $10,000 – $15,000– 2 kW power system $16,000 - $20,000– 5 kW power system $35,000 - $45,000
(will power most homes)– You can get federal tax credits up to $2000 and some state
tax credits as well
Wind Power
• Heat from the sun does not warm the earth evenly, causing the flow of air masses = wind
• Fastest growing energy source• Cost is decreasing
Wind Farms
• Farmers can sell excess energy back to their local utility!!
• The windiest places on Earth could generate 10 times more energy needed on earth!!
• Problem: Transporting the energy from rural areas to where it is needed
Biomass Power - any organic matter that is used as an energy source
• Plants material, manure, methane, alcohol• Major source of energy in developing countries!
• Problems: – cutting too many trees can cause severe environmental
problems– Burning can release large amounts of air pollution
Methane – a byproduct of decomposition
• Britain’s first Dung-Fired Power plant using the methane released from cow manure for energy
• US uses some energy from methane produced from landfills!
Ethanol
• Produced from biomass!• Benefits:
– Renewable– Less emissions
• Cons:– Takes lots of land– Rise in produce prices
Hydroelectricity – energy produced by moving water
• 20% of the worlds electricity• Leading Countries
– Canada– US– Brazil– China– Russia– Norway
Hydroelectric Energy
• Benefits– Inexpensive to
operate– No air pollution– Last longer than
fossil fuel plants– Flood control– recreation
• Disadvantages– Changes a rivers flow– Reservoir floods the
area• Displaces people
– Reduces water flow– Destroys salmon
fisheries– Dam failure– Sedimentation
Today: the era of large dam construction is most likely overWe are now using micro-hydropower
Geothermal Energy – energy from heat in the earth’s crust
• US is the worlds largest producer of geothermal energy
Costs of Geothermal Heat Pumps
• Heat pump = $3,500 - $7,500• Drilling/installation = $10,000 - $25,000• You can get federal tax credits up to $2000 and some
state tax credits
Alternative Energy – energy sources that are still in development
• How to get off the alternative list?– Prove it is cost effective– Environmental effects must be acceptable
• Current Alternative energy sources– Tidal Power Ocean– Ocean Thermal Energy Conversion (OTEC)– Hydrogen
Tidal Power
• Tides – the movement of water caused by gravitational attractions between the sun, Earth and the moon.
• Currently used in – France– Russia– Canada
Cost is high and not many placessuitable enough
Ocean Thermal Energy Conversion
• Warm ocean surface temperatures and cold subsurface temperatures are used to create electricity
• Surface temps boil water making steam….• Cold subsurface water cools the steam• Problems
– Pumping water costs too much– Pumping cold water to the surface could cause
problems
Hydrogen??
• The most abundant element in the universe!• Burning it produces water vapor – not pollution• Electricity is used to split water molecules to
get hydrogen gas• Challenges:
– Takes a lot of energy to make– Not safe to store
Fuel Cells
• Combining Hydrogen and Oxygen produces electricity and its byproduct is water!
• No Emissions!!
Energy Efficiency - % of energy put into a system that does useful work
• Ex: a light bulbs light output not its heat energy
• More than 40% of energy produced in the US is wasted!!
• How to improve– Public transport– More efficient engines, i.e. fuel cells
Hybrid Cars
• Less emissions• Small efficient gas engine• Electric motor• Convert breaking energy into electricity• Aerodynamic• Lightweight material
Cogeneration
• Using the same fuel source for two forms of energy– Ex: wasted heat from a furnace can be used to
produce electricity
Energy Conservation – saving energy by reducing use and waste
• How can we do this in our lives???
Energy Efficient Home
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