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?

• 1965 power outage– 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

• 2003 blackout in northeast US– Took all of 9 seconds– Caused by heat wave and high demand– 7 states and 1 Canadian province affected

• Earthquake / tsunami wrecked Japanese nuclear power plant 2011 – 1000’s dead– nuclear power plants destroyed

• Conclusions– 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 US3 Grids: East, West, Texas

Just What IS the “Electrical Grid”

• 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:– 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

The Power Grid

Substation

Utility Pole

Transmission Lines

From Power Plant

EQ3: Where does electricity come from?

68% fossil10% nuclear22% renewable

66% fossil19% nuclear15% renewable

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.

Oil Crises: 1973 & 1979Embargo and Rationing

Text of Picture

“Gas stealers beware !!!”

1979

Notice diesel less thangasoline

Ration Stamps from World War II

Oil Consumption by Region / Year

Oil Consumption by Region / Year

Where does electricity come from?

Conventional: 95.5%– Coal (44.9%) – Natural Gas (23.4%)– Nuclear (20.3%)– Hydro-electric (6.9%)

• Other Renewables: 4.5% – Solar– Wind– Geothermal– Wave

* Rounding error

Solid Fuels: Coal• Carbon-based fuels said to cause global warming*• Coal:

– 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

• 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• Takes energy from splitting the atom

– Neutrons hit other neutrons causing “chain reaction”– Uranium decays into different “isotope” – same element, different number of neutrons

• “Chain reaction” controlled – By “moderator” – water slows chain reaction– Control Rods – stop reaction altogether

• 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) – • 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

Nuclear Power

Secondary Loop

Primary Loop

Containment Structure blewoff in Japanese power plantfrom steam explosion

Steam is condensed back to water and to “feed” steam generator

Reactor

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– 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– 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

– Peak loads (diesel generator)– Emergencies– Small, remote operations– Mobile operations

• Commonly have 6/8/12 cylinders (large diesel engine)– 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

• 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?

• 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

• 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

• Think of electricity as having energy like water has energy

• 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

How does water have energy?

• 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

50#

50#

Generating Electricity Chemically

• 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 voltage generated

VM

Using That Electricity

• 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

VM

Just like that water will fall to the ground

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

Resistance Changes

with Length• This chart at right

shows that resistance of a wire – goes up with size – can be standardized

for a given length.

• If you double a wires length, you double its resistance.

Small

Large

Diameter

DC Ohms

Zoom in as needed to see ratings