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Renewable Energy
Resources
• Inexhaustible energy refers to energy resources that are constant and will never run out.
• Includes the Sun, wind, water, and geothermal energy
Inexhaustible Energy Resources
Solar Energy• The sun helps to cause global winds and
currents in the ocean.
Global Wind Currents
Passive Solar
• Solar energy can be– Passive
• Example sun shining through a window or sky light
Active Solar
• Active solar collectors often convert the energy of sunlight into electricity– Example
• Solar panels
• Active solar collectors can also heat water that is then distributed through the house.– Example
• Tube collectors
Active solar collectorthat heats water
Solar Energy Benefits
• Solar energy is clean and inexhaustible (it will never run out).
• Passive solar energy is relatively inexpensive.
Disadvantages of Solar Energy
• Cloudy days means no energy collected.
• Solar energy doesn’t work at night.
• While the energy can be stored in batteries, it is difficult to store large amounts of the electrical energy created by solar energy.
• Old batteries must be discarded, which can pollute the environment.
Wind Energy
• Wind energy comes from solar energy since wind is caused by the sun heating the Earth unevenly.
• Windmills have been used throughout history to – grind corn and wheat into flour– pump water
• Windmills now are used mostly to generate electricity.
Historical Uses of Windhttp://www.teachersdomain.org/asset/phy03_img_wind/
For grinding grain
For pumping water
• Hydroelectric energy is electricity produced by water power.
• Water in rivers is dammed. The water runs through turbines in the dam that turn generators that make electricity.
• Other ways to capture the power of water:– Tides moving in and out along ocean shores turn
generators for electricity.– Waves cause generators to bob up and down,
creating electricity.
Energy from Water
• Dams can stop migration of fish and other river species.
• Upstream lakes fill with sediment on dammed rivers.
• Downstream erosion increases in dammed rivers.
• Land is often flooded upstream from a dam.• Wildlife habitats are damaged by damming.
Problems with Using Water
• Geothermal energy comes from the heat inside Earth.– Water is pumped down into Earth over hot
rocks. The heated water turns to steam which turns a turbine that turns a generator to produce electricity.
• In some countries, natural groundwater is heated by magma and pumped directly to the consumer for use in the home.
Energy from the Heat Within
Geothermal Energy in Iceland
• http://www.youtube.com/watch?v=XRAQrDduaU0
• Renewable energy refers to energy resources that can be replaced in nature or by humans within a relatively short period of time.
• Includes biomass, such as trees and crops, and biomass transformed into fuels.
Renewable Energy Resources
• Biomass energy is derived (gotten) from burning organic material such as wood, grains, alcohol, and garbage.– Bio means life.–Mass refers to matter.
Biomass
• Wood, when burned, releases a lot of heat energy.
• Many countries still rely mostly on wood for heating and cooking.
• Wood smoke can pollute the air, and habitats are destroyed when trees are removed in large amounts from an area.
Burning Wood
• Grains and grasses can produce alcohol and oil which can be converted into fuels for transportation.– Ethanol– Biodiesel
• These fuels are considered more efficient than burning biomass directly (such as burning wood).
Alcohol and Oil from Grains and Grasses
• Burnable garbage is a resource that could be used to generate electricity.
• Using garbage to burn for energy would help keep landfills from filling up.
• However, some garbage is toxic when burned.
Energy from Burning Garbage
• Garbage, when it rots, produces a gas—METHANE.
• This is a renewable form of methane that does NOT come from fossil fuels.
• The methane is collected as it rises, and is burned for heat energy.
Other Energy from Garbage
