Sources of Energy pp.145-151
Feb 24, 2016
Nearly all the energy on Earth comes originally from the sun.
•Plants get energy for photosynthesis from sunlight.•Animals get energy from food, including plants.•Over time plant and animal remains changed into coal, oil and natural gas.•Photovoltaics change solar power directly into electricity•Heat from sunlight creates wind, which windmills change into electricity or mechanical energy.
Fossil FuelsCoal, oil and natural gas are called fossil fuels because they take millions of years to be created, like fossils.
Fossil fuels are nonrenewable resources because we are using them much faster than they can be replaced.They will run out!
Burning fossil fuels releases pollution into the air.
Fossil FuelsCOAL COMES FROM PLANTS ALIVE MILLIONS OF YEARS AGO.
OIL AND NATURAL GAS COME FROM ANIMALS AND BACTERIA FROM MILLIONS OF YEARS AGO.
Nuclear EnergyNuclear energy comes from releasing the energy that holds the nucleus of a uranium atom together.This releases lots of heat (thermal energy).
The nuclear fuel is still radioactive for millions of years after it’s removed from the power plant.
HydroelectricityUses the potential energy of water to generate electricity.The water has to be stored by a dam. Then it passes through the dam’s generators.
Hydroelectricity is a renewable resource because the source can be replaced.
Inexhaustible ResourcesInexhaustible means they can never run out!
Examples include solar power, wind power and geothermal energy.
These are also called alternative resources.
Geothermal EnergyUnderground temperature stays same year roundPower plants pump water deep down to be heated to steam to generate electricity.Home Heat Pumps
In summer: underground cooler than house so pump water down to cool it, then pump through house
In winter: underground hotter than house so pump water down to heat it, then pump through house
Inexhaustible ResourcesFrom sunlightDepends on weatherExpensivePassive solar uses light to heat waterPhotovoltaics change light energy into electricity
From underground heatNo pollutionExpensive
Wind Power
Solar Power
Geothermal• From kinetic
energy of wind• Depends on weather• No pollution• Not pretty to look at• Can kill birds that fly into windmill
NotesNearly all the energy on Earth comes originally from the sunCoal, oil and natural gas are called fossil fuels. Nonrenewable resources are used faster than they can be replaced. (Examples: coal, oil, natural gas)Renewable resources can be replaced. (Example: hydroelectricity)Inexhaustible resources can never run out! (Examples: solar, wind, geothermal energy)Photovoltaics change sunlight to electric energy.
Fossil FuelsADVANTAGESWe already use themPortable
DISADVANTAGESLimited amounts leftNeed large amounts of fuelReleases lots of pollutionLeaves lots of ash/residue
Nuclear EnergyADVANTAGESUses small amounts of fuelNo air pollutionReleases large amounts of energy
DISADVANTAGESLimited amounts of uraniumLeaves radioactive waste
HydroelectricityDISADVANTAGESCan harm fish swimming upstreamDrought can lower water level too low to generate powerExpensive to build
• No pollution• Available on demand
ADVANTAGES
Solar PowerADVANTAGESInexhaustibleNo pollution
DISADVANTAGESNeed sunlight (night, clouds)ExpensiveNeeds large spaces
Wind PowerADVANTAGESNo pollution
DISADVANTAGESDepends on weatherNeeds large spacesCan kill birdsNot pretty to look at
Geothermal EnergyADVANTAGESAvailable 24/7 No pollution
DISADVANTAGESNot available everywhereExpensive
Sources of Energy
• Nearly all the energy on Earth comes originally from the sun• Coal, oil and natural gas are called fossil fuels. • Nonrenewable resources are used faster than they can be replaced. (Examples: coal, oil, natural gas)• Renewable resources can be replaced. (Example: hydroelectricity)• Inexhaustible resources can never run out! (Examples: solar, wind, geothermal energy)• Photovoltaic cells change sunlight directly into electricity.
Fossil Fuels
Advantages Disadvantages
Already being used Limited amounts left
Portable Causes much pollution
Nuclear Energy
Advantages Disadvantages
No air pollution Radioactive waste for millions of years
Need just small amount of fuel Limited amount of uranium
Get large amount of energy
Hydroelectricity
Advantages Disadvantages
No pollution Can harm fish
Always available Drought can lower water too far
Expensive
Need large amounts of space
Solar Power
Advantages Disadvantages
No pollution Not available at night or cloudy days
Inexhaustible Expensive
Needs large amounts of space