electricity environmental science 2. electricity defined electricity is a form of energy electricity...

ElectricityElectricity

Environmental Science 2Environmental Science 2

Electricity DefinedElectricity Defined

Electricity is a form of energyElectricity is a form of energyElectricity is a flow of charged Electricity is a flow of charged particles, usually electrons – particles, usually electrons – this is called a currentthis is called a currentA current is not defined by how A current is not defined by how fast the charged particles fast the charged particles move, but by how many move, but by how many particles moveparticles moveParticles become charged Particles become charged when an atom either loses or when an atom either loses or gains electronsgains electronsIf the atom loses an electron If the atom loses an electron the particle becomes positive the particle becomes positive (because there are more (because there are more positive protons than negative positive protons than negative electrons) electrons)


There are There are several several factors that cause the factors that cause the charged particles charged particles movemove– 11) ) There has to be an There has to be an

electrical potential electrical potential differencedifference, meaning there , meaning there has to be areas of has to be areas of unbalanced charges unbalanced charges (this (this does not means there has does not means there has to be areas of positive and to be areas of positive and negative, but regions of negative, but regions of different charges)different charges)


– 2) 2) There needs to be a There needs to be a load – a load is anything load – a load is anything that uses electricitythat uses electricity. The . The potential energy difference potential energy difference needs to be maintained in needs to be maintained in order to keep the current order to keep the current alivealive

– 3) 3) Whether a material is a Whether a material is a conductor or an insulatorconductor or an insulator

The more available space for The more available space for the current to flow the better the current to flow the better conductor a material is (e.g. conductor a material is (e.g. metal & water)metal & water)The less available space for The less available space for the current to flow the better the current to flow the better insulator a material is (e.g. insulator a material is (e.g. wood & rubber)wood & rubber)


– 4) 4) There needs to be a There needs to be a complete path for the complete path for the current to flow – this is current to flow – this is called a circuit. called a circuit. A A circuit allows the circuit allows the charged particle to charged particle to move to through a move to through a charged region, then charged region, then to the load, then to the load, then through another through another charged areacharged area

Electricity DefineElectricity Define

A closed circuit (see A closed circuit (see picture) allows the picture) allows the energy to flowenergy to flowAn open circuit does An open circuit does not allow the energy not allow the energy to flowto flowThere are two types There are two types of connectionsof connections– 1) Series1) Series– 2) Parallel2) Parallel


Series connectionsSeries connections– The energy flow moves The energy flow moves

through the area of through the area of potential energy, through potential energy, through all the loads, then returns all the loads, then returns to the sourceto the source

Parallel connectionsParallel connections– There is more than one There is more than one

path for the charges to flow path for the charges to flow – the current can bypass a – the current can bypass a load and still complete the load and still complete the circuitcircuit

How electricity is producedHow electricity is produced

The production of The production of electricity starts with electricity starts with any electrically any electrically conductive material conductive material moving across a moving across a magnetic field magnetic field


Another form of energy is Another form of energy is needed to rotate a turbine needed to rotate a turbine – the most common form – the most common form is steam is steam (kinetic energy)(kinetic energy)A conductive material is A conductive material is attached to the turbineattached to the turbineA magnetic field A magnetic field surrounds the turbine and surrounds the turbine and generates electricity as generates electricity as the turbine rotatesthe turbine rotatesA generator is used to A generator is used to collect and transfer the collect and transfer the electricityelectricity


Electricity starts in the Electricity starts in the power plantpower plant

Transmission lines Transmission lines carry the electricity to carry the electricity to a a local substation local substation

The electricity is then The electricity is then distributed distributed to power to power lines and carried to lines and carried to sourcessources

Electricity produced by fossil fuelsElectricity produced by fossil fuels

Coal, oil or natural gas is Coal, oil or natural gas is burned to create steam, burned to create steam, which rotates a turbinewhich rotates a turbine

Over half of the U.S.’s Over half of the U.S.’s energy comes from fossil energy comes from fossil fuelsfuels

Natural gas can also be Natural gas can also be used directly by burning used directly by burning the gas and the the gas and the combustion gases rotate combustion gases rotate the turbinethe turbine

Electricity produced by fossil fuelsElectricity produced by fossil fuels

Disadvantages of fossil fuels:Disadvantages of fossil fuels:– There is a finite supply of fossil fuelsThere is a finite supply of fossil fuels– Greenhouse gases are produced when Greenhouse gases are produced when

burningburning

Advantages of fossil fuels:Advantages of fossil fuels:– Cheapest source of energy to dateCheapest source of energy to date– Infrastructure is already in placeInfrastructure is already in place

Electricity produced by windElectricity produced by wind

Uses wind turbines to Uses wind turbines to generate electricitygenerate electricityA large number of wind A large number of wind turbines creates a wind turbines creates a wind plant or wind farmplant or wind farmThe blades on the wind The blades on the wind turbine are turned by the turbine are turned by the force of wind to rotate a force of wind to rotate a turbine to produce turbine to produce electricityelectricityWind accounts for less Wind accounts for less than 1% of the country’s than 1% of the country’s electricity productionelectricity production

Electricity produced by windElectricity produced by wind

Disadvantages to wind energyDisadvantages to wind energy– At first cost was higher than traditional At first cost was higher than traditional

methods of energy production; however, now methods of energy production; however, now the cost is comparable to traditional methodsthe cost is comparable to traditional methods

– Not effective for areas of the U.S. with little Not effective for areas of the U.S. with little windwind

– Wind is an unreliable source of energyWind is an unreliable source of energy– Wind farms are more expensive to build than Wind farms are more expensive to build than

coal operated plantscoal operated plants

Electricity produced by geothermal Electricity produced by geothermal energyenergy

Geothermal power Geothermal power plants use steam from plants use steam from the Earththe Earth to rotate a to rotate a turbine to produce turbine to produce electricityelectricityThree types:Three types:– Dry steam: uses Dry steam: uses

geysers as main geysers as main source of steam – only source of steam – only two plants in the U.S. two plants in the U.S. (Northern California & (Northern California & Yellowstone National Park)Yellowstone National Park)


Three types:Three types:– Flash steam: most common; use energy from Flash steam: most common; use energy from

geothermal reservoirs where water can reach geothermal reservoirs where water can reach around 360around 360°F – steam is separated from the °F – steam is separated from the water and powers the turbinewater and powers the turbine

– Binary cycle: operates at lower temperatures Binary cycle: operates at lower temperatures of around 225° - 360°F – main difference of around 225° - 360°F – main difference between Flash Stream is the hot water is between Flash Stream is the hot water is mixed with an organic compound so that the mixed with an organic compound so that the water can be reusedwater can be reused


Disadvantages of Disadvantages of geothermal energy:geothermal energy:– Not enough electricity Not enough electricity

could be produced to meet could be produced to meet U.S. demands – better for U.S. demands – better for small scale areassmall scale areas

– Geothermal energy is Geothermal energy is limited or nonexistent in limited or nonexistent in some regions of the U.Ssome regions of the U.S

Accounts for less than Accounts for less than 1% of the country’s 1% of the country’s electricity productionelectricity production

Electricity produced by nuclear Electricity produced by nuclear energyenergy

Uranium fuel rods are Uranium fuel rods are placed into reactor placed into reactor cores and then placed cores and then placed in waterin waterLike fossil fuels, heat Like fossil fuels, heat is produced and the is produced and the steam steam turns a turbineturns a turbineThe turbine is then The turbine is then connected to a connected to a generatorgenerator

Electricity produced by nuclear Electricity produced by nuclear energyenergy

Nuclear energy accounts for about 20% of the Nuclear energy accounts for about 20% of the country’s electricity productioncountry’s electricity productionAdvantages of nuclear energy:Advantages of nuclear energy:– No greenhouse gases are producedNo greenhouse gases are produced– Most viable electricity source as fossil fuels are Most viable electricity source as fossil fuels are

consumedconsumed

Disadvantages of nuclear energy:Disadvantages of nuclear energy:– After the reaction is complete the uranium rods After the reaction is complete the uranium rods

become radioactivebecome radioactive– Concerns of decommissioning the plant when it is Concerns of decommissioning the plant when it is

retired retired

Electricity produced by water Electricity produced by water

Utilizes stored energy Utilizes stored energy from a dam (river or from a dam (river or reservoir)reservoir)When the water is When the water is released it flows over released it flows over a turbine a turbine and and activates a generatoractivates a generatorCurrently the world’s Currently the world’s largest source of largest source of renewable energy renewable energy (15% of electricity)(15% of electricity)

Electricity produced by waterElectricity produced by water

Disadvantages of hydro energyDisadvantages of hydro energy– Limited to areas of water sourcesLimited to areas of water sources– Ecological impacts include: Ecological impacts include:

Downstream rivers are deprived of nutrient-rich silt Downstream rivers are deprived of nutrient-rich silt because of damsbecause of dams

Flooding around the reservoirFlooding around the reservoir

Decrease in water flow inhibit fish to move up Decrease in water flow inhibit fish to move up stream stream

New methods of electricity New methods of electricity productionproduction

Solar TowerSolar Tower– A 3,280 ft tower, shaped much like A 3,280 ft tower, shaped much like

a chimney, uses solar panels to a chimney, uses solar panels to heat air and causes the air to riseheat air and causes the air to rise

– As the air rises (much like air rising As the air rises (much like air rising in a chimney), the air accelerates in a chimney), the air accelerates to around 35mphto around 35mph

– The rising warm air drives 32 wind The rising warm air drives 32 wind turbines inside the towerturbines inside the tower

– Combining solar and wind allows Combining solar and wind allows the tower to operate 24 hours a the tower to operate 24 hours a dayday

– A solar tower is schedule to be constructed in Las Vegas by the end of 2013


Solar absorbing Solar absorbing shinglesshingles– The panels can be attached to The panels can be attached to

an existing roof, making it an existing roof, making it more appealing to consumersmore appealing to consumers

– Solar shingles will most likely Solar shingles will most likely be introduced in Hawaii and be introduced in Hawaii and California due to comparable California due to comparable costs between fossil fuels and costs between fossil fuels and solar shinglessolar shingles

– Becoming more popular in Becoming more popular in sunny areassunny areas


MicrobesMicrobes– Researchers are testing green

algae to increase the production of hydrogen gas

– Once scientists perfect the output of hydrogen gas, they will then work on ways to store the gas to use in hydrogen vehicles

– Researchers are also looking for ways to have bacteria produce electricity directly by placing them microbial fuel cells

– Commonly placed in waste water, which helps clean the water as well as produce electricity


Windmills in the skyWindmills in the sky– Windmills 15000 ft in the air to Windmills 15000 ft in the air to

utilize the strong, persistent utilize the strong, persistent windswinds

– The electricity feeds to the The electricity feeds to the ground through a cableground through a cable

– Benefits of the project – hides Benefits of the project – hides the unattractive wind farms & the unattractive wind farms & consistent supply of wind consistent supply of wind energyenergy

– The Federal Aviation The Federal Aviation Administration has already Administration has already approved the project approved the project

– Problems still need to be Problems still need to be worked out before productionworked out before production

FIGURE 1: American Electricity Demand FIGURE 1: American Electricity Demand Compared to The Top 5 Consumption Compared to The Top 5 Consumption CountriesCountries

Source: Energy Information Administration, Annual International Report, 2001.

Ways to save electricityWays to save electricity

““Vampire” appliances Vampire” appliances – Cost consumers around $3 billion a year ($200 per Cost consumers around $3 billion a year ($200 per

household)household)– Satellite receivers for TVSatellite receivers for TV– Garage door openersGarage door openers– Clock radiosClock radios– Answering machinesAnswering machines– Microwave ovens and standard ovens with clocksMicrowave ovens and standard ovens with clocks– Computers (when left of sleep mode)Computers (when left of sleep mode)


Obvious ways:Obvious ways:– Turn off lights and Turn off lights and

faucets when not in faucets when not in useuse

– Do not open windows Do not open windows when heater/air when heater/air conditioner are in useconditioner are in use

– Turn off appliances Turn off appliances and electronics when and electronics when not in use (e.g. TV, not in use (e.g. TV, VCR, computers, VCR, computers, radios) radios)


Less obvious ways:Less obvious ways:– Buy appliances that have the Energy Star Buy appliances that have the Energy Star

labellabel– Set home thermostat in winter to 68Set home thermostat in winter to 68° during ° during

the day and 55° at nightthe day and 55° at night– Set home thermostat in summer to 78° when Set home thermostat in summer to 78° when

you are home and 85° when you are awayyou are home and 85° when you are away– Use trees to help shade home and windowsUse trees to help shade home and windows– Use energy efficient light bulbsUse energy efficient light bulbs

Ways to save electricity Ways to save electricity

Less obvious ways:Less obvious ways:– Clean or replace air filters on heater and air Clean or replace air filters on heater and air

conditioner monthly during operating seasonconditioner monthly during operating season– Wash only full loads of laundry and full loads Wash only full loads of laundry and full loads

of dishesof dishes– Do not preheat your oven when cooking or Do not preheat your oven when cooking or

cook dishes simultaneously in the ovencook dishes simultaneously in the oven

SourcesSourcesClean Energy Basics www.nrel.gov/clean_energy Clean Energy Basics www.nrel.gov/clean_energy – Introduction to hydroelectric powerIntroduction to hydroelectric power– Introduction to geothermal electricity productionIntroduction to geothermal electricity production– Introduction to wind energyIntroduction to wind energy

Safe Tree Kids www.safetreekids.net/basics/save.htmlSafe Tree Kids www.safetreekids.net/basics/save.html– How to save energyHow to save energy– How electricity is producedHow electricity is produced

Wired News www.wired.com/news.htmlWired News www.wired.com/news.html– Solar tower of power finds homeSolar tower of power finds home– Raise the roof: power sourceRaise the roof: power source– Fill’er up, with microbesFill’er up, with microbes– Windmills in the skyWindmills in the sky

Science Blog www.scienceblog.comScience Blog www.scienceblog.com– Cleaner electricity, cars and trucks can save consumers billions of dollars, says Cleaner electricity, cars and trucks can save consumers billions of dollars, says

new UCS analysisnew UCS analysis– Bacterium cleans up uranium, generates electricityBacterium cleans up uranium, generates electricity– Why burn coal when wind power is cheap and plentiful?Why burn coal when wind power is cheap and plentiful?– Energy expert:”Ampire” appliances suck electricity – even when they are offEnergy expert:”Ampire” appliances suck electricity – even when they are off

SourcesSources

Science made simple. “What is static electricity?” Science made simple. “What is static electricity?” www.sciencemadesimple.com/static.htmlwww.sciencemadesimple.com/static.htmlEnergy information administration. “What is electricity” Energy information administration. “What is electricity” and “Electricity generation” www.eia.doe.govand “Electricity generation” www.eia.doe.govPhysics Post. “Circuit Basics” www.physicspost.comPhysics Post. “Circuit Basics” www.physicspost.comDefenders of Wildlife. “Geothermal energy resources: Defenders of Wildlife. “Geothermal energy resources: principles and recommendations” principles and recommendations” www.defenders.org/habitat/remew/geothermal.htmlwww.defenders.org/habitat/remew/geothermal.htmlEnergy Educators of Ontario. “Energy fact sheet: hydro-Energy Educators of Ontario. “Energy fact sheet: hydro-electric power” www.iclei.org/EFACTS/HYDROELE.HTMelectric power” www.iclei.org/EFACTS/HYDROELE.HTM

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