Unit 3: Characteristics of Electricity
Chapter 12: Electricity and the Environment
p 395-417
Terms
mechanical energy
solar energy
electrochemical energy
solar cell
photovoltaic cell
hydroelectric
fossil fuels
geothermal
nuclear fission
thermonuclear
wind power
tidal power
greenhouse gas
global warming
thermal pollution
non-renewable
renewable
generator
petroleum
Energy Sources
Review from Chapter 10 notes
Energy
the ability of an object to exert a force on another object to change its motion.
Energy can be classified as being either kinetic or potential.
Kinetic Energy
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the energy an object has based on its motion.
Machines, wind, waves, tides, and sound (moving objects or particles)
Electric currents and lightning (moving charges)
Light and other radiation (moving photons)
Heat (thermal energy)
the “stored” energy based on its position.
Potential Energy
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Gravitational  hydroelectric power, roller coaster, wrecking ball
Elastic  springs, guitar strings, hockey sticks, soccer balls
Chemical (bonds between atoms or molecules) burning coal, gasoline
Electric Potential (build up of excess charge)  electrochemical cells, static electricity
Energy Sources for Producing Electrical Energy can be classified as:
1. Electrochemical Energy  energy from special chemical reactions called oxidation-reduction (red-ox)
 examples: batteries
2. Solar Energy
 the light energy from the Sun
 solar cells = photovoltaic cells
(photo = light, voltaic = potential energy difference)
3. Mechanical Energy  the sum of kinetic and potential energies
Mechanical energy can be used to rotate a turbine
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hydroelectric  kinetic energy from moving (falling) water
wind  kinetic energy from moving air
tidal  gravitational energy from seawater rising and falling with tides
wave  energy from seawater rising and falling due to waves
geothermal  heat energy from the ground (geo = Earth)
fossil fuels  chemical energy released by burning
nuclear  energy released as atoms change from one element to another
Generators
Water wheels and windmills have been used for centuries to convert the energy of moving water and air into
useful work.
Generator
a device that produces electrical energy from mechanical energy.
Turbine
a device attached to blades that “catch” a moving fluid (air or water) causing the turbine to rotate
Parts
A generator has a coil of wire and strong magnets that rotate relative to each other
A rotating turbine is attached to either the coil of wire or the magnets
Method
Moving air or water cause a turbine to rotate.
The turbine causes the coil of wire to rotate relative to the strong magnets.
The relative motion of the coil of wire and the magnets push electrons through the wire.
Generators make potential difference (voltage).
Ways to increase voltage: 1. Faster rotation
2. Stronger Magnets
3. More wire rotating
World energy sources
World energy sources
coal, oil, gas, hydro, biomass, solar, wind, wave, nuclear, geothermal, and tidal.
All energy sources are ultimately solar, nuclear, or tidal
Outline and distinguish between renewable and non-renewable energy sources.
Renewable
resources that are maintained at constant levels
can be used again (wind, tidal) or quickly replenished (wood, biomass)
Non-renewable
finite sources which are being depleted and will run out
cannot be reused and requires significant time to replenish (fossil fuels, uranium)
Fossil fuels
chemicals made from fossilized life
Coal – from tropical rainforests
Oil (petroleum)
 gasoline, diesel fuel, home heating oil, jet fuel, asphalt
– from plankton  microscopic aquatic life
Natural Gas
 methane, propane (barbeque), butane (lighters)
The relative proportions of world use of the different energy sources that are available.
Most of the world’s energy comes from fossil fuels.
Renewable energy sources make up less than 10%.
Percentages given are for reference only.
NON-RENEWABLE (93%)
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RENEWABLE (8%)
fossil fuels (86%)
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wood / biomass (4%)
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oil (40%)
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hydro (3%)
o
coal (23%)
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solar (0.5%)
o
gas (23%)
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wind (0.3%)
nuclear (7%)
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geothermal (0.2%)
Solar Powered Energy
Energy Type
Hydroelectric
Wind
Wave
Biomass
Kinetic Energy (energy of motion)
water flowing downhill
air flowing from high pressure to low pressure
surface waves of ocean/lake
burning plant material heats water that rises
Coal
Petroleum
(oil and gas)
burning coal heats water that rises
burning oil and gas heats water that rises
How the Sun drives this energy
Sun powers Water Cycle: lifts water vapour
Wind is caused by uneven heating of Earth’s surface
Wind near surface or water makes waves
Plants use photosynthesis to make complex
chemicals from sunlight
Coal is fossilized (tropical) plants
Plankton (tiny marine life) form petroleum
Photovoltaic (solar) cells use sunlight to separate charges in a silicon panel to create a potential difference (voltage)
Tidal Energy
The gravitational attraction of Moon pulls the ocean waters outward making high tides and low tides
There are always two high tides and two low tides on Earth.
The tides rotate with the Moon. There are about 11 hours between high tides.
The Bay of Fundy between Nova Scotia and New Brunswick has the highest tides on Earth.
Nuclear Energy
Radioactive Elements
Some elements, such as uranium, are unstable and change into more stable elements, like lead.
This change releases energy as nuclear radiation and heat.
Geothermal Energy uses the heat in the crust to heat water pumped into the crust.
Nuclear Fission
Uranium atoms are bombarded with neutrons that make the uranium split into pairs of
smaller atoms and more neutrons that continue the chain reaction.
Nuclear Power comes from controlled nuclear fission that heats water to turn a turbine
Nuclear Bomb/Meltdown comes from an uncontrolled nuclear chain reaction
Advantages and Disadvantages
Key areas to analyze:
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Location of generating station
closeness to the consumers (cities, towns, etc.)
easy access for maintenance and repair
closeness to important habitats
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Infrastructure
cost of buildings, dams, cooling towers
technology
transportation of resources and waste
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Environmental impact
4. Resources and Requirements
Flooding and other changes to habitats
 Availability and cost of raw resources
Air pollution: greenhouse gases, smoke
 Required amount of power production
Water pollution: thermal pollution, chemical pollution
Solid waste: spent radioactive fuel rods
Thermal Generating Stations  heat water into steam that drives turbine
Includes power plants using (1) fossil fuels, (2) nuclear fission, and (3) geothermal energy
Require: large volumes of cold water
Location: near shoreline of oceans or large lakes
Thermal Pollution: the returning water is warmer than normal.
 Marine life suffers from not enough dissolved gases, especially CO2 and O2
Fossil Fuel Powered Stations  burn fossil fuels to heat water into steam that drives turbine
Combustion = burning fossil fuels and other organic compounds
Greenhouse Gases: carbon dioxide (CO2) and other gases that keep heat from escaping into space
Global Warming  the increase in the average global temperature of the Earth
The increasing amount of CO2 and other greenhouse gases caused by human activity is believed to
contribute significantly to global warming and climate change.
Fossil Fuels
Renewable or
Non-Renewable
Energy
Nearest Location
Required
Resources
Cost of
Resources
Non-renewable
Renewable
Thermal (heat)
Lingan (Coal)
Fuel supply
Water for cooling
Coal and Oil are
relatively cheap
and available
Kinetic (motion)
Wreck Cove
Water reservoir that
“falls” through dam
“Free” resource
Few good rivers
remaining
Energy Type
Fossil Fuel Combustion (Thermal)
Nuclear (Thermonuclear) Reactors
Solar Cells (Photovoltaic cells)
Hydroelectric Dams
Wind Turbines
Hydroelectric
Photovoltaic
Solar
Ontario (Sarnia)
Many hours of
sunshine daily
“Free” resource
Best near equator
with cloudless skies
Wind
Lingan, Glace Bay
Constant daily
winds
Advantages
 High power production
 Fuel easy to transport
 Cheap to start and maintain
 Common globally
 High power production
 Large reserves of uranium in Canada
 No CO2 (greenhouse gas) emissions
 Free, renewable energy source (the Sun)
 “Clean” energy production – no greenhouse gases
 No chemical or thermal pollution
 No moving parts to break down
 Free, renewable energy source (rain/water cycle)
 “Clean” energy production – no greenhouse gases
 Free, renewable energy source (wind from solar)
 “Clean” energy production – no greenhouse gases
Nuclear
Thermonuclear
Point Lepreau, NB
Nuclear fuel rods
Water for cooling
Radioactive ore
Contamination risk
Tidal
Annapolis Valley
Large high and low
tide difference
Disadvantages
 Combustion make pollution; acid rain
 Combustion makes Greenhouse Gases (CO2)
 Mining fossil fuels damages environment
 Non-renewable
 Radioactive waste – safe transport and storage
 Risk of reactor problems (Chernobyl)
 Specialized nuclear reactor
 Thermal water pollution
 Non-renewable
 Only make electricity during the day
 Unreliable due to clouds
 Large area needed for high power production
 Expensive initial costs
 Limited to larger, faster rivers
 Dams cause flooding of habitats
 Moving parts exposed to dirt and water break down
 Unreliable  low wind speeds
 Large area needed for high power production
 Many windy areas are far from consumers