1. Chapter 18 Renewable Energy 18-1 Renewable Energy Today Renewable Energy: from sources that are constantly being formed (ex. solar, wind, moving water, Earth’s heat)

2. I. Solar Energy – Power from the Sun 1. Passive Solar Heating: uses the sun’s energy to heat something directly –Passive Solar Homes –Large south-facing windows –Well insulated –Overhanging roof -summer = sun’s path is high in the sky (roof provides shade) -summer = sun’s path is high in the sky (roof provides shade) -winter – sun’s path is lower in the sky (sunlight can shine into the home) -winter – sun’s path is lower in the sky (sunlight can shine into the home)

3. Passive Solar Home

4. Active Solar Heating: energy from the sun is gathered by collectors and used to heat water or to heat a building

5. Photovoltaic Cells

6. Photovoltaic Cells: solar cells – convert sun’s energy into electricity Produces a very small electrical current Produces a very small electrical current A small city would need hundreds of acres of solar panels A small city would need hundreds of acres of solar panels Require extended periods of sunshine Require extended periods of sunshine Energy has to be stored in batteries or fed back into the grid (net-metering) Energy has to be stored in batteries or fed back into the grid (net-metering) Becoming increasingly efficient & less expensive Becoming increasingly efficient & less expensive Great potential in developed countries, where energy consumption is minimal Great potential in developed countries, where energy consumption is minimal

7. Wind Farm

8. II. Wind Power – Cheap & Abundant Wind moves a turbine to generate electricity Wind moves a turbine to generate electricity Fastest growing energy source in the world Fastest growing energy source in the world Wind Turbines are cost effective and can be built in 3 months Wind Turbines are cost effective and can be built in 3 months Wind Farms: large arrays of wind turbines Wind Farms: large arrays of wind turbines Turbines take little space Turbines take little space –Some farmers add wind turbines to their land and sell the electricity An underdeveloped resource – scientists estimate that the windiest spots on Earth could generate more than 10 times the energy used worldwide An underdeveloped resource – scientists estimate that the windiest spots on Earth could generate more than 10 times the energy used worldwide Problem = transporting electricity from rural areas where it is generated to urban centers Problem = transporting electricity from rural areas where it is generated to urban centers

9. III. Biomass – power from living things Biomass fuel: any organic matter that is used as an energy source (plant material, manure, etc.) Biomass fuel: any organic matter that is used as an energy source (plant material, manure, etc.) Fossil fuels don’t count because they are nonrenewable Fossil fuels don’t count because they are nonrenewable Wood & Dung are major sources of energy in developing countries Wood & Dung are major sources of energy in developing countries Although wood is renewable – it can result in habitat loss, deforestation, and soil erosion if trees are cut down faster than they can grow Although wood is renewable – it can result in habitat loss, deforestation, and soil erosion if trees are cut down faster than they can grow Burning wood & dung can release harmful air pollution Burning wood & dung can release harmful air pollution

10. Biofuels

11. 1. Methane: produced when bacteria decompose organic wastes –Burn it to make heat / electricity –China ferments manure to make gas for heating & cooking –Britain opened a dung-fired power plant in 2002 –Some landfills generate electricity w/ methane made from decomposing trash 2. Alcohol Ethanol – made by fermenting fruit or agricultural waste Ethanol – made by fermenting fruit or agricultural waste Corn is a major source in the US Corn is a major source in the US Gasohol: gasoline + ethanol Gasohol: gasoline + ethanol –produces 28% less emissions than fossil fuels, but produces 38% less energy

12. DAM

13. IV. Hydroelectricity – Power from Moving Water Hydroelectric Energy: produced from moving water Hydroelectric Energy: produced from moving water –Dam is built across a river to hold back a reservoir of water –Water is released to turn a turbine –Turbine spins a generator to produce electricity

14. DAM

15. Benefits: Benefits: –Expensive to build, but inexpensive to operate & last longer than fossil-fuel powered plants –No air pollutants –Flood control –Water for drinking, agriculture, industry, recreation Disadvantages: Disadvantages: –Changes a river’s flow –Reservoir floods large areas of habitat above the dam –People are often displaced –Water flow below the dam is reduced – disrupting ecosystems downstream –Prevents salmon from swimming upriver to spawn –As river slows, it deposits sediment behind the dam instead of enriching the land farther downstream –Plant matter decaying in reservoirs can release large amounts of greenhouse gasses

16. Modern Trends - Micro-hydropower Modern Trends - Micro-hydropower –Electricity produced in a small stream w/out a big dam –Turbine may even float and not block the river at all!

17. V. Geothermal Energy – Power from the Earth Energy from heat in the Earth’s crust Energy from heat in the Earth’s crust In some areas, deposits of water in the Earth’s crust are heated by energy within the Earth In some areas, deposits of water in the Earth’s crust are heated by energy within the Earth Geothermal Power Plants pump heated water or steam from rock formations and use the water or steam to power a turbine – the water is usually returned to the crust Geothermal Power Plants pump heated water or steam from rock formations and use the water or steam to power a turbine – the water is usually returned to the crust

19. Geothermal Heat Pumps: Energy for Homes Geothermal Heat Pumps: Energy for Homes –Temp. of the ground is nearly constant year-round –Geothermal heat pump – uses stable underground temp. to warm and cool homes Simply a loop of piping that circulates a fluid underground Simply a loop of piping that circulates a fluid underground

20. 18-2 Alternative Energy and Conservation Alternative Energy: energy sources that are still in development Must be Must be –Cost effective –Acceptable environmental effects Government investment is often the only way to research some of these possibilities. Government investment is often the only way to research some of these possibilities.

21. Tidal Power Works like a hydroelectric dam Works like a hydroelectric dam Tide rises, water flows behind a dam Tide rises, water flows behind a dam Sea level falls trapping water behind the dam Sea level falls trapping water behind the dam Reservoir is released to turn a turbine Reservoir is released to turn a turbine Used in France, Russia, and Canada Used in France, Russia, and Canada Pros: renewable, non-polluting Pros: renewable, non-polluting Cons: high cost of building and maintaining, few locations are suitable Cons: high cost of building and maintaining, few locations are suitable

23. Ocean Thermal Energy Conversion (OTEC) 1. Warm surface water used to boil sea water (boils at low temp. at low pressure in a vacuum chamber) 2. Steam turns turbine 3. Deep, cold ocean water cools the steam to make reusable water not cost effective (so far) not cost effective (so far) environmental effects unknown environmental effects unknown

24. Hydrogen – A Future Fuel Source? The most abundant element in the universe The most abundant element in the universe Can be burned as a fuel Can be burned as a fuel Does not release pollutants associated w/ burning fossil fuels and biomass Does not release pollutants associated w/ burning fossil fuels and biomass When hydrogen is burned, it combines with oxygen to produce water vapor and small amounts of nitrogen oxides When hydrogen is burned, it combines with oxygen to produce water vapor and small amounts of nitrogen oxides Can be produced by using electricity to split molecules of water Can be produced by using electricity to split molecules of water The Challenge of Hydrogen: Takes a lot of energy to produce Takes a lot of energy to produce 1 alternative: use electricity from solar cells or wind power to split water molecules to produce hydrogen  then store it in pressurized tanks and transport it in pipelines 1 alternative: use electricity from solar cells or wind power to split water molecules to produce hydrogen  then store it in pressurized tanks and transport it in pipelines Fuel Cells: produces electricity chemically (like a battery) Combines hydrogen fuel w/ oxygen from the air Combines hydrogen fuel w/ oxygen from the air Electricity is produced Electricity is produced Water is the only byproduct Water is the only byproduct Can be fueled by anything that contains plenty of hydrogen (natural gas, alcohol, gasoline) Can be fueled by anything that contains plenty of hydrogen (natural gas, alcohol, gasoline) Soon portable electronics (phones, games) may be powered by micro-fuel cells (fueled w/ alcohol)  no charging or changing batteries Soon portable electronics (phones, games) may be powered by micro-fuel cells (fueled w/ alcohol)  no charging or changing batteries

25. Energy Efficiency: the percentage of energy put into a system that does useful work Energy efficiency (in %) = energy out/energy in X 100 Energy efficiency (in %) = energy out/energy in X 100

26. Efficient Transportation Developing efficient engines Developing efficient engines Increasing the use of public transportation systems Increasing the use of public transportation systems

27. Hybrid Cars Energy-efficient vehicles currently in use Energy-efficient vehicles currently in use Use a small, efficient gasoline engine most of the time Use a small, efficient gasoline engine most of the time Also use an electric motor when extra power is needed (i.e. accelerating) Also use an electric motor when extra power is needed (i.e. accelerating) Converts some of the energy of braking into electricity (stored in battery) Converts some of the energy of braking into electricity (stored in battery) Sometime shut off the gasoline engine (i.e. when stopped at a red light) Sometime shut off the gasoline engine (i.e. when stopped at a red light) Cost less to refuel Cost less to refuel Produce less harmful Produce less harmfulEmissions VIDEO

28. Cogeneration: the production of 2 useful forms of energy from the same fuel source i.e. waste heat from an industrial furnace can power a steam turbine that produces electricity i.e. waste heat from an industrial furnace can power a steam turbine that produces electricity Energy Conservation: saving energy Using energy-efficient devices, wasting less energy Using energy-efficient devices, wasting less energy Using less of any resource usually translates into saving energy Using less of any resource usually translates into saving energy Most of the energy lost from homes is lost through poorly insulated windows, doors, walls, and the roof Most of the energy lost from homes is lost through poorly insulated windows, doors, walls, and the roof Replace old windows w/ new high efficiency windows Replace old windows w/ new high efficiency windows Seal gaps around doors and windows with caulking or weather stripping Seal gaps around doors and windows with caulking or weather stripping

30. Ways to Save Energy Around The House