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Power and Energy
What would you do if the lights went
out and we ran out of gasoline?
Essential Question
• EQ1: What are our essential energy needs?
• EQ2: How would your life be made more
difficult if energy sources were interrupted?
• EQ3: Where does electricity come from?
• EQ4: Where does gasoline come from?
– What is the price of gasoline, adjusted for
inflation over time?
– How have our oil supplies changed over time?
– What geopolitical factors have played a role?
EQ1: What are our essential energy needs?
• Electricity
– Powers all homes, businesses
– Many industrial processes
• Heating
– Keeping homes warm
– Industrial process
• Locomotion
– Movement of goods and people
EQ2: How would your life be made more difficult if energy
sources were interrupted?
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1965 power outage
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80,000 sq. miles + 2 Canadian provinces affected
30 million people affected
President involved
Looting was a concern
Baby boom 1966 … many more babies born that year
2000 California
– “Rolling blackouts” the result of bankrupt and corrupt power companies
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2003 blackout in northeast US
– Took all of 9 seconds
– Caused by heat wave and high demand
– 7 states and 1 Canadian province affected
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Earthquake / tsunami wrecked Japanese nuclear power plant 2011
– 1000’s dead
– nuclear power plants destroyed
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Conclusions
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All brings to mind looming infrastructure crisis in the US
Concerns about terrorists and natural disasters
Opportunities in power plant ops, electrical/civil engineering, security
A Some outages resulted
Power Grids in the US
3 Grids: East, West, Texas
Just What IS the “Electrical Grid”
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The largest “machine” ever invented
Like the internet, it’s “everywhere”
Like the internet, it “just happened”
A result of the Industrial Revolution
Edison and Westinghouse battled over AC vs. DC
– AC won because of Tesla’s inventing transformers
– AC doesn’t lose as much energy over distance
• Consists of:
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Power plants: 600-1700 Megawatts (MW = 1,000,000 W)
Step-up Transformers: EHV – Extra High Voltage (270 Kilovolts)
Transmission lines: High Voltage (110 KV +)
Neighborhood Substations: (50 KV)
Power pole transformers: (~13,000 volts)
Your house (240V/120V)
The
Power Grid
From Power Plant
The Power Grid
Transmission Lines
Substation
Utility Pole
EQ3: Where does electricity come from?
Dept of Energy created in 1979 to plan for crises
like the oil shortages of 1973 / 1979.
How are we doing at increasing supplies of
renewable “green” energy as percent of
whole? Answer? We’re not doing that well.
68% fossil
10% nuclear
22% renewable
66% fossil
19% nuclear
15% renewable
Oil Crises: 1973 & 1979
Embargo and Rationing
Text of Picture
Notice diesel less than
gasoline
1979
“Gas stealers beware !!!”
Ration Stamps from World War II
Oil Consumption by Region / Year
Oil Consumption by Region / Year
Where does electricity come from?
Conventional: 95.5%
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Coal (44.9%)
Natural Gas (23.4%)
Nuclear (20.3%)
Hydro-electric (6.9%)
• Other Renewables: 4.5%
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Solar
Wind
Geothermal
Wave
* Rounding error
Solid Fuels: Coal
• Carbon-based fuels said to cause global warming*
• Coal:
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Biggest energy source available in US
90% of coal in US used for electricity production
Supplies 45% of electricity
Used to produce steam
“Clean Coal” techniques being perfected
Much opposition to “strip mining” (strip mining / mountain-topping
• Coal arrives by train (coal transport)
– Over a mile long
– 100 cars with 100 tons of coal in each one (10,000 tons)
– A large plant needs at least one train every day
• Coal consumption
– 6.75 billion tons in world
– USA consumes 14% of world total
• Steam plants only 35% efficient - Rest goes to atmosphere
•Many people do not believe in man-caused global warming
A Coal-Fired
Power Plant
Liquid Fuels
• Petroleum
– Can pollute oceans, land; much opposition since BP oil spill /
Exxon Valdez)
– Fuel Oil
• Must be refined (Oil Refinery: from jet fuels to gasoline to kerosene to
diesel (leaving tar) – lightest fuel goes to top, tar at bottom
• Used for heating (northeast US)
• 1% US Electricity is from oil (emergencies)
– Gasoline
• Powers most vehicles in US ($0.35/gal road tax one of highest in
nation (“road tax”)
– Diesel
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Ignition comes from compression heat (no spark plug)
On-Road / Off-Road
Used to power personal vehicles
Used for larger vehicles trucks
Used for tractors, bull dozers, cranes
Off-road diesel dyed red, not charged $0.41/gal “road tax” (also
highest)
Liquid / Gaseous Fuels
• Natural Gas – home meter
– US has large supply
– Cleaner than petroleum
– Home heating in south, power plants, large vehicles
• WS city buses (WS diesel-electric buses – a big PRIUS)
• Some suggest converting large “semi’s” to burn NG
• Could also work in trains
• Biodiesel – can be used in any diesel vehicle or engine
– Chemical process using plant and animal fats and alcohol
– 3.8 million tons worldwide, mostly in Europe
– Only 200-800 million gallons in US (2006-2010)
• Ethanol
– From food (corn) in the US
• Raises price of food
• Government gives “subsidies” ($$$) to farmers to grow it
– From sugar cane (Brazil)
• Vegetable Oil (not enough to go around ... can’t grow
enough)
– Supplies going down as gas prices rise
Nuclear Power
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Takes energy from splitting the atom
– Neutrons hit other neutrons causing “chain reaction”
– Uranium decays into different “isotope” – same element, different number of neutrons
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“Chain reaction” controlled
– By “moderator” – water slows chain reaction
– Control Rods – stop reaction altogether
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Heats up water in “primary loop” (power plant)
Primary water boils water in “secondary loop”
Like conventional steam plant after that
Accidents: (details not on test)
– 1979: 3-Mile Island (Pennsylvania) –
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Unit 2 meltdown
No loss of life
The last nuclear power plant built in US in 1979)
Look for movie called “China Syndrome”
– 1986: Chernobyl – Ukraine/USSR –
• Reactor melt down caused steam explosion - lives lost at scene from accident and shutdown
• Many people got cancer for years
• Left area a wasteland
Containment Structure blew
off in Japanese power plant
from steam explosion
Nuclear Power
Steam
Generator
Secondary Loop
Reactor
Primary Loop
Steam is condensed back
to water and to “feed”
steam generator
Prime Movers
• Prime Movers (PM’s) – mechanical
equipment that turns a driven load
• In electrical production, this is a generator
– Steam Engines
– Gas Turbines
– Diesel Engines
– Water Turbine
– Wind Turbines
Driven Equipment
• Driven Equipment – mechanical equipment
using power from prime mover
• In electrical production, this is a generator
• Could also be
– Pumps
– Propeller shafts (ships)
– Turbo-fans (airplanes)
Steam Turbines
• Steam turbine (rotor, rotor1) most common PM
• Long time to get on line / expensive to take out of service.
• Steam turbine is “external combustion” engine
– Steam’s energy comes from boiler
– Water is condensed, used again in steam power plant
• Run on high pressure steam
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Rotor stages act like pinwheels
Blades are hit with the high pressure steam
Most rows blades act like nozzles (turbine blade type)
Each rotor gets bigger as energy of steam is used up
• Connected to reduction gears to reduce speed but
increase torque (“turning force”) (reduction gears)
Gas Turbines (GT)
• Just like engines on airplanes
• Used in remote locations and for emergency power needs
• Has compressor, combustor, HP turbine, LP turbine
(turbine image)
– Rotating and stationary blades (LM2500 opened)
– LM2500 is engine Mr. Goodman worked on for US Navy
• “Internal combustion” engines - all heat starts/ends in GT
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Compressor in front (stages get smaller) turns HP turbine
Power turbine in back (stages get bigger)
Uses up more energy in each stage
Rows (stages) of blades act like pinwheels
Compressed air mixes with fuel in “combustor”
After HP turbine, combustion gases spin “power (LP) turbine”
Reduction gears decrease speed, increase torque.
Diesel Engines
• “Internal combustion” engines - all heat starts and is used in
the diesel
• In electrical production used for
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Peak loads (diesel generator)
Emergencies
Small, remote operations
Mobile operations
• Commonly have 6/8/12 cylinders (large diesel engine)
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Fuel is ignited from heat of compression
Can run on a variety of fuels
Different designs for different speed / torque needs
May or may not have reduction gears
Best left running: starting / stopping not efficient
• Used on ships/trains to drive wheel motors or propellers
Water Turbines
• Used in hydro-electric power plants (hydro-electric plant)
• Famous ones in US:
– Hoover Dam (Lake Meade, Las Vegas)
– Tennessee Valley Authority (Depression work project)
• Large one in China: Three Gorges Dam
• Only 7% of power in US is hydro-electric; 3.4% worldwide
• Positives:
– Clean, renewable, quiet (picture of water turbine)
– Controls flooding, provides for irrigation
– helps navigation with locks and dams
• Negatives:
– Floods valleys where people live
– Disturbs natural lives (spawning) of fish* (Northwest salmon)
– Causes problems with natural flow and build-up of “silt” in river
* Many dams have “fish ladders” where fish can use to climb back up to spawn
Wind Turbines (Internal Parts)
• 3-bladed fans drive generators up to 7.5 megawatts (million watts)
• Built in stages
– Base, mid-tower, top, power head
– Blades up to 130 ft)
– Towers 200 - 300 ft
• Dependent on regular weather patterns
– Located on land or sea (power from wind)
– Heating/cooling rates of land vs. water
• North American “wind corridor” in US Midwest (wind corridor)
• 3.35% of worldwide power by 2013, 8 percent by 2018)
• Could lower use natural gas use for electricity by 20%.
– Saving used for electricity or transportation
– Used in US
• Very expensive to build, takes a long time to develop
– Complex gearing spins blades and adjusts “pitch” (angle to wind) of blades
Geothermal
• Draws heat from earth
• Only works in certain parts of
planet
• Iceland has a LOT of
Geothermal
• Creates steam from water in
earth as hot as 180°C / 350°F
• Drives turbines like other steam
plants
• Sends water to cooler part of
earth
Solar Power
• Sun hits panels made of semi-conductor
– Mostly Silicon
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Creates DC – direct current
Electronic “inverters” change DC to AC
Transformers “step up” and reduce voltages
Enters grid like other power
Small % of US power
Expensive to create
– Large “solar farms” exist but are expensive
– Must store energy in batteries at night
– Government offers “subsidies” to
encourage use
Not Mr. Goodman’s house
Solar Farm
What will be on the test?
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Energy needs
Blackouts (cause / effects / lessons)
Electrical grids
Sources of energy / energy use / effects of
Factors affecting energy prices
Power plants (types, processes,
machinery, terminology)
Basic Facts About Electricity
• Think of electricity as
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having energy like water
has energy
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• Water flowing in a river is
called “current” and so is •
the movement of
electrons through a wire •
• Water pressure built up
in a balloon is like
voltage stored in a
battery
Everything seeks a
“lower energy state”
Water will go from high
to low if allowed to flow
Electricity is the
movement of electrons
Electricity seeks the
“path of least
resistance”the way
water will leak out of a
tank
How does water have energy?
50#
50#
• If this bag of water is left alone, the water will
fill up some shape of the bag.
• If a weight is dropped on the bag, the water
will go from high pressure to low pressure
Generating Electricity Chemically
VM
• Metals give off a
negatively charged
particles called electrons,
some more than others
• Sometimes acids
(electrolyte) help the
electrons move easier
• When 2 different metals
are placed next to each
other electrons to move to
the more positively
charged
• The more electrons that
are moved, the higher the
VM
Using That
Electricity
Just like that water will fall to the ground
• When all the
electrons are on
one side of a
battery ...
• And that battery is
connected across a
circuit ...
• The electrons will
try to get back to a
place where there
are too few
electrons.
• In the mean time it
may light a lamp
Ohm’s Law - The Basic Fact
• Ohm’s law (E = I x R)
is the basic fact of all
electricity
• It is to electricity what
Newton’s second law
(F = m x a) is to
moving objects
Calculating Resistance
• A voltmeter is place
“across” (in parallel
with) the resistor
• An ammeter is place
in line (in series) with
the resistor
• Using Ohm’s law, the
resistance can be
calculated
Heat &
Resistanc
e
• Resistance
changes with
temperature
DC Ohms
Resistance
Diameter
Changes
with Length
• This chart at right Small
shows that resistance
of a wire
– goes up with size
– can be standardized
for a given length.
• If you double a wiresLarge
length, you double its
resistance.
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