Energy (Part 2)UNIT FIVE, LESSON 5.1BY MARGIELENE D. JUDAN

LESSON OUTLINEHeat as Energy TransferSources of Energy

HeatThe measure of internal energy that has been absorbed or transferred from one body to another.Increasing internal energy = heatingDecreasing internal energy = cooling

Heating can occur when:1. There is a temperature difference

Energy moves from higher to lower temperature.2. An object gains heat energy from energy transformation (ex.

mechanical to heat energy by rubbing your hands)

HEAT AS ENERGY TRANSFERConductionConvection

ConductionTransfer of energy from molecule to moleculeHeat energy is transmitted through collisions between neighboring moleculesHappens primarily in solids

ConductionConductors – materials that allow heat to pass throughInsulators – materials that doesn’t allow heat to pass through efficiently (Note: Insulators also transfer heat, but they are not as efficient as conductors)

ConvectionThe movement of fluids (liquids or gases) from a colder to warmer region producing a currentHappens primarily in fluids (liquids and gases)Warm air = less dense = it risesCold air = denser = it sinks

SOURCES OF ENERGYSolar energyWind energyHydroelectric EnergyGeothermal Energy BiomassFossil FuelsNuclear Energy

Solar energyEnergy from the sunSolar cells called “photovoltaic cells” or “photoelectric cells”, convert light directly into electricity.Advantages: free, nonpollutingDisadvantages: doesn’t work at night unless stored in a battery, expensive, unreliable esp. in cloudy areasDifference: doesn’t use a turbine to generate electricity; uses photochemical reactions

Unlike solar energy, all the other sources of energy have the same mechanism. They turn the turbines which in turn, turns the generator to generate electricity.

1. An energy source turns the turbines2. Turbines turn generators3. Generators generate electrical power

The only difference is that, they use various energy source to turn the turbine.Three energy source:1. wind (wind energy)2. flowing water (hydroelectric energy)3. Steam (Geothermal Energy, Biomass, Fossil Fuels, Nuclear Energy)

Wind energy (uses wind)Uses wind to turn the turbinesAdvantages: free, nonpolluting, tourismDisadvantages: weather dependent, expensive, noise pollution, affects television reception, can kill migrating birds if hit by blades

Hydroelectric (uses flowing water)Uses flowing water to turn the turbinesCommon in dams, rivers, canalsAdvantages: free, nonpolluting, reliable than wind or solar energy, always availableDisadvantages: very expensive, causes flooding, affected by summer or drought

The next slides are the energy sources that uses different mechanisms to produce steam.Geothermal Energy – uses steam below the earthBiomass – burns biomass to heat water and make steamFossil Fuels – burns fossil fuels to heat water and make steamNuclear Energy – splits atoms to heat water and make steam

Geothermal energyUses steam below the earth’s surface to turn the turbinesHoles are drilled underground for steam to come outAdvantages: low cost after initial investment, doesn’t take up much spaceDisadvantages: near volcanoes, underground hazards like sulfur and toxic gases may be present near the plant

BiomassBurns biomass to heat water and make steam, in order to turn the turbinesBiomass – biological material derived from living, or recently living organismsAdvantages: recycles waste, fuel (waste) is cheapDisadvantages: emits greenhouse gases and air pollutants

Fossil fuelsBurns fossil fuels to heat water and make steam, in order to turn the turbinesFossil fuels – fossilized organic materials (coal, oil, natural gas)Advantages: easy transport of oil/gas to power plant, produces huge amount of energy from small amounts of fuel, very efficientDisadvantages: emits greenhouse gases and air pollutants, limited supply

Nuclear energyUsing the energy from nuclear fission to heat water, make steam, and tur the turbinesNuclear fission – splitting of the nucleusUses radioactive elements like Uranium and PlutoniumAdvantages: reliable source, inexpensive, produces huge amount of energy from small amounts of fuel, small waste, does not produce smoke or greenhouse gasesDisadvantages: difficult to dispose and manage, expensive to build, radioactive hazards when the reactor breaks

Renewable and NonrenewableRenewable – easily replaced; abundantNon-renewable – takes a long time to get replaced (usu. hundreds and millions of years)

On the next slide, compare the consumption of energy sources. Notice that the non-renewable resources are used more than the renewable resources. It only means that time will come when much of the energy sources we have will be depleted.

Based on the chart, which is the most reliable energy source?

Answer:Hydropower/ hydroelectricIt is the renewable energy with the highest reliability. (35%)

SOURCES OF ENERGYSolar energy renewableWind energy renewableHydroelectric Energy renewableGeothermal Energy renewableBiomass renewableFossil Fuels non-renewableNuclear Energy non-renewable

Main Sources of Energy TodayPetroleum (fossil fuel) 37% will run out in 53 yearsNatural gas (fossil fuel) 25% will run out in 54 yearsCoal (fossil fuel) 21% will run out in 110 years

Source: business-standard.com

Our main source of energy is fossil fuel, which is non-renewable. Thus, it is very important to conserve and appreciate these energy sources that we still have today. They are not here to serve us forever.

The driving force in almost all of earth’s energyThe sun. It powers almost everything. Without sun, there would be no global winds, global currents, and natural resources. No plants means that there will no producers. Life would not be possible without the sun because this earth will become an energy-less place. Without energy, there is no work. Without work there is no life.

Sources:Science Links 7http://www.sciencemusicvideos.com/structure-and-functio

n-levels-of-biological-organization-worksheet/http://www.countrysideinfo.co.uk/successn/intro.htm