energy of moving water

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Energy of Moving WaterStudent Guide


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TheNEEDProjectP.O.Box10101,Manassas,VA201081.800.875.5029www.NEED.org

Energy is ound in diferent orms, such as light, heat, sound, and

motion. There are many orms o energy, but they can all be put into

two categories: potential and kinetic.

Potential and Kinetic Energy

Potential EnergyPotential energy is stored energy and the energy o position.

Potential energy includes:Chemical energy is energy stored in the bonds o molecules. Fossil

uels such as coal, oil, and natural gas contain chemical energy

that was stored in the remains o ancient plants and animals rom

which they were ormed millions o years ago.

Biomass is any organic material (material that was once living

materialsuch as wood or corn) that can be used as a uel.

Biomass contains stored chemical energy, produced rom the sun

through the process o photosynthesis.

Energy of position. A rock on top o a hill contains potential

energy because o its position. I a orce pushes the rock, it rolls

down the hill because o the orce o gravity. The potential energy

is converted into kinetic energy until it reaches the bottom o thehill and stops.

Stored gravitational energy. The water in a reservoir behind a

hydropower dam is another orm o potential energy. The stored

energy in the reservoir is converted into kinetic energy as the water

ows down a large pipe called a penstock and spins a turbine.

The turbine spins a shat inside the generator, where magnets

and coils o wire convert the kinetic energy into electrical energy

through a phenomenon called electromagnetism. This electricity

is transmitted over power lines to consumers who use it to perorm

many tasks.

Kinetic EnergyKinetic energy is energy in motion; it is the motion o

electromagnetic and radio waves, electrons, atoms, molecules,

substances, and objects. Forms o kinetic energy include:

Electrical energy is the movement o electrons. The movement o

electrons in a wire is called current electricity. Lightning and static

electricity are other examples o electrical energy.

Radiant energy is electromagnetic energy that travels in waves.

Radiant energy includes visible light, x-rays, gamma rays, and radio

waves. Light is one type o radiant energy. Energy rom the sun

(solar energy) is an example o radiant energy.

Energy makes change; it does things or us. It moves cars along the road and boats on the

water. We use it to bake cakes in the oven and keep ice rozen in the reezer. It plays our avorite

songs on the radio and lights our homes. Energy helps our bodies grow and allows our minds

to think. Scientists dene energy asthe ability to do work or the ability to make a change.

What is Energy

POTENTIAL TO KINETIC ENERGY

HILL

KineticEnergy

PotentialEnergy

HYDROPOWER DAM

RIVER

SWITCHYARD

view from above

MAGNETSCOPPER COILS

ROTATINGSHAFT

1. Water in a reservoir behind a hydropower dam ows through a large intakescreen, which lters out large debris, but allows sh to pass through.

2. The water travels through a large pipe, called a penstock.

3. The force of the water spins a turbine at a low speed, allowing sh to passthrough unharmed.

4. Inside the generator, the shaft spins coils of copper wire inside a ring ofmagnets. This creates an electric eld, producing electricity.

5. Electricity is sent to a switchyard, where a transformer increases the voltage,allowing it to travel through the electric grid.

6.Water ows out of the penstock into the downstream river.

GENERATOR

GENERATOR

TURBINE

RESERVOIR

IntakeDAM

PENSTOCK

DETA

IL

1

2

3

4

5

6



Thermal energy is the internal energy in substances; it is the

vibration and movement o the atoms and molecules within

substances. The more thermal energy in a substance, the aster the

atoms and molecules vibrate and move. Geothermal energy is an

example o thermal energy. Thermal energy is sometimes calledheat.

Sound is the movement o energy through substances in

longitudinal (compression/rareaction) waves. Sound is produced

when a orce causes an object or substance to vibrate; the energy

is transerred through the substance in a longitudinal wave.

Motion is the movement o objects and substances rom one place

to another. Objects and substances move when a orce is applied

according to Newtons Laws o Motion. Wind is an example o

motion energy.

Law of Conservation of EnergyThe Law o Conservation o Energy is not about saving energy. The

law states that energy is neither created nor destroyed. When we

use energy, it does not disappear; we change it rom one orm into

another. A car engine, or example, burns gasoline, converting the

chemical energy in the gasoline into useul motion; some o the

energy is also converted into light, sound, and heat. Solar cells

convert radiant energy into electrical energy. Energy changes orm,

but the total amount o energy in the universe remains the same.

Energy EciencyEnergy eciency is the amount o useul energy produced by a

system compared to the energy input. A perect energy-ecientmachine would convert all o the input energy into useul work,

which is impossible. Converting one orm o energy into another

orm always involves a loss o usable energy. This is called a

conversion loss and is usually in the orm o heat. This waste heat

spreads out quickly into the surroundings and is very dicult to

recapture.

A typical coal-red plant converts about 35 percent o the energy

in the coal into electricity. The rest o the energy is lost as heat. A

hydropower plant, on the other hand, converts about 95 percent o

the energy in the water owing through the system into electricity.

Most transormations are not very ecient. The human body is a

good example. Your body is like a machine, and the uel or yourmachine is ood. The typical body is less than ve percent ecient

at converting ood into useul work such as moving, thinking, and

controlling body processes. The rest is lost as heat. The eciency o

a typical gasoline powered car is about 15 percent.

ENERGY TRANSFORMATIONS

Chemical Motion

Radiant Chemical

Chemical Motion

Electrical Thermal

EFFICIENCY OF A POWER PLANT

BOILER

STEAM LINE

TURBINE

CONDENSERFEED

WATER

GENERATOR

SWITCHYARD

ELECTRICITY

TRANSMISSION

FUEL BURNING

ELECTRICITY GENERATION

12

3

45

FUEL SUPPLY

How a Thermal Power Plant Works

1. Fuel is fed into a boiler, where it is burned to release thermal energy.

2. Water is piped into the boiler and heated, turning it into steam.

3. The steam travels at high pressure through a steam line.

4. The high pressure steam turns a turbine, which spins a shaft.

5. Inside the generator, the shaft spins coils of copper wire inside a ring of magnets.This creates an electric eld, producing electricity.

6. Electricity is sent to a switchyard, where a transformer increases the voltage,allowing it to travel through the elect ric grid.

ost thermal power plants are about 35 percent ecient. Of

the 100 units of energy that go into a plant, 65 units are lost as

one form of energy is converted to other forms. 35 units of

energy are produced to do usable work.

100 units ofenergy go in

THERMAL ENERGY

MOTI ON EN ERGY

35 units ofenergy

come out

6

Fuel Sources

Petroleum Coal Natural Gas Uranium Biomass

CHEMICAL

OR NUCLEAR

ENERGY


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Sources of EnergyWe use many diferent sources to meet our energy needs, all o

which have advantages and disadvantages. Some are cheap;

others are expensive. Some contribute to global warming; others

are pollution-ree. Some are limited in their supplies; others areabundant. Some are always available; others are only available part

o the time.

Energy sources are classied into two groupsrenewable and

nonrenewable. In the United States, most o our energy comes

rom nonrenewable energy sources. Coal, petroleum, natural gas,

propane, and uranium are nonrenewable energy sources. They

are used to make electricity, heat our homes, move our cars, and

manuacture all kinds o products.

They are called nonrenewable because the reserves o the uels

are limited. Petroleum, or example, was ormed millions o years

ago rom the remains o ancient sea plants and animals. We cannot

make more petroleum in a short time.Renewable energy sources include biomass, geothermal energy,

hydropower, solar energy, and wind energy. They are called

renewable because they are replenished by nature in a short time.

Day ater day, the sun shines, the wind blows, the rivers ow, and

plants grow. Heat rom inside the Earthgeothermal energyis

continuously made by the radioactive decay o elements in the

Earths core.

We can harness this renewable energy to do work or us. We use

renewable energy sources mainly to make electricity.

U.S. ENERGY CONSUMPTION BY SOURCE, 2008

PETROLEUM 37%Uses: transportation,

manufacturing

COAL 22.6%Uses: electricity, manufacturing

NATURAL GAS 23.5%Uses: heating, manufacturing,

electricity

URANIUM 8.5%Uses: electricity

PROPANE 1%Uses: heating, manufacturing

Source: Energy InformationAdministration

BIOMASS 3.9%Uses: heating, electricity,

transportation

HYDROPOWER 2.5%Uses: electricity

GEOTHERMAL 0.4%Uses: heating, electricity

WIND 0.5%Uses: electricity

SOLAR 0.1%Uses: heating, electricity

NONRENEWABLE

RENEWABLE



Electricity must be generated quickly to meet the changing demand

o consumers. Large amounts o electricity, however, cannot be easily

stored. Power plants that can easily change the amount o electricity

they can make, such as hydropower plants, are very important.

As we use more technology, the demand or electricity continues to

grow. In the U.S. today, more than 40 percent o the energy we use is

in the orm o electricity. This amount is expected to rise and poses

many challenges or the nation, with no easy answers.

Global climate change is one important issue to consider when

discussing electricity production. Most U.S. electricity is produced

by ossil uels, which when burned emit greenhouse gases. Should

ossil uel plants be required to reduce emissions? Should we build

more nuclear power plants? Can we reduce demand by cutting

back the energy we use? Can renewable energy sources meet

rising demand? How much are consumers willing to pay or a

reliable supply o electricity, or a cleaner environment, or ecient

technologies? These questions will only become more important.

A Mysterious Force

What exactly is the orce we call electricity? It is moving electrons.And what exactly are electrons? They are tiny particles ound in

atoms. Everything in the universe is made o atomsevery star,

every tree, every animal. The human body is made o atoms. Air and

water are too. Atoms are the building blocks o the universe. Atoms

are so small that millions o them would t on the head o a pin.

Atomic StructureAtoms are made o smaller particles. The center o an atom is called

the nucleus. It is made o particles called protons and neutrons

that are approximately the same size. (The mass o a single proton is

1.67 x 10-24 gram.)

Protons and neutrons are very small, but electrons are much, much

smaller1,836 times smaller, to be precise. Electrons move around

the nucleus in orbits a relatively great distance rom the nucleus. I

the nucleus were the size o a tennis ball, the atom with its electrons

would be 1,250 eet in diameterthe size o the Empire State

Building.

I you could see an atom, it might look a little like a tiny center

o balls surrounded by giant invisible clouds (or energy levels).

Electrons are held in their levels by an electrical orce. The protons

and electrons o an atom are attracted to each other. They both carry

an electrical chargea orce within the particle.

Protons have a positive charge (+) and electrons have a negative

charge (). The positive charge o the protons is equal to the negative

charge o the electrons. Opposite charges attract each other. When

an atom is neutral, it has an equal number o protons and electrons

The neutrons carry no charge and their number can vary. Neutrons

act as a glue to hold the nucleus together.

The Nature of Electricity

Electricity is diferent rom primary energy sources; it is a secondary source o energy, which

means we must use another energy source to produce electricity. Electricity is sometimescalled an energy carrier because it is an ecient and sae way to move energy rom one place

to another.

ATOM

proton neutron

nucleus

electron


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ElementsAn element is a substance composed o atoms that have a given

number o protons. The number o protons is an elements atomic

number and determines the elements identity.

Every atom o hydrogen, or example, has one proton and one

electron. Every atom o carbon has six protons and six electrons.

The atomic mass o an element is the combined mass o its

protons, neutrons, and electrons. Atoms o the same element may

have diferent numbers o neutrons, but they will all have the samenumber o protons. Atoms o the same element that have diferent

numbers o neutrons are called isotopes o that element.

ElectronsThe electrons usually remain within a well-dened region at a

relatively constant distance rom the nucleus. These well-dened

regions are called energy levels. Within various energy levels,

there are areas o diferent shapes, called orbitals, where there is a

high probability that the electrons will be ound. The energy level

closest to the nucleus can hold a maximum o two electrons. The

next level can hold up to eight. The outer levels can hold more, but

the outermost level that contains electrons can hold no more thaneight.

The electrons in the energy levels closest to the nucleus have a strong

orce o attraction to the protonsthey are stable. Sometimes, the

electrons in the outermost energy level are not strongly held. These

electronsvalence electronscan be pushed or pulled rom their

energy level by a orce. These are the electrons that are typically

involved when chemical reactions occur.

MagnetsIn most objects, the molecules are arranged randomly. They are

scattered evenly throughout the object. Magnets are diferent

they are made o molecules that have North- and South-seeking

poles. Each molecule is really a tiny magnet.

The molecules in a magnet are arranged so that most o the North-

seeking poles point in one direction, and most o the South-seeking

poles point in the other direction. This creates a magnetic eld

around a magnetan imbalance in the orces between the ends o

a magnet. A magnet is labeled with North (N) and South (S) poles.

The magnetic eld in a magnet ows rom the North pole to the

South pole.

Electromagnetism

A magnetic eld can produce electricity. In act, magnetism andelectricity are really two inseparable aspects o one phenomenon

called electromagnetism. Every time there is a change in a

magnetic eld, an electric eld is produced. Every time there is a

change in an electric eld, a magnetic eld is produced.

We can use this relationship to produce electricity. Some metals,

such as copper, have electrons that are loosely held. They can be

pushed rom their valence shells by the application o a magnetic

eld. I a coil o copper wire is moved in a magnetic eld, or i

magnets are moved around a coil o copper wire, an electric current

is generated in the wire.

ELEMENT SYMBOL PROTONS ELECTRONS NEUTRONS

Hydrogen H 1 1 0

Lithium Li 3 3 4

Carbon C 6 6 6

Nitrogen N 7 7 7

Oxygen O 8 8 8

Magnesium Mg 12 12 12Copper Cu 29 29 34

Silver Ag 47 47 51

Gold Au 79 79 118

Uranium U 92 92 146

SEVERAL COMMON ELEMENTS

BAR MAGNET

LIKE POLES

OPPOSITE POLES



Producing ElectricityA generator is an engine that converts mechanical energy into

electrical energy using electromagnetism. A turbine is a device that

converts the ow o air, steam, or water into mechanical energy to

power a generator.

Power plants use huge turbine generators to make the electricity we

use in our homes and businesses. Power plants use many uels to

spin a turbine. They can burn coal, oil, or natural gas to make steam

to spin a turbine. They can split atoms o uranium to heat water intosteam. They can also use the power o rushing water rom a dam or

the energy in the wind to spin the turbine.

The turbine is attached to a shat in the generator. Inside the

generator are magnets and coils o copper wire. The generator can

be designed in two ways. The turbine can spin coils o wire inside

magnets, or can spin magnets inside coils o wire. In either design,

the electrons are pushed rom one copper atom to another inside

the wire by the moving magnetic eld.

In the diagram on the right, coils o copper wire are attached to

the turbine shat. The shat spins the coils o wire inside two huge

magnets. The magnet on one side has its North pole to the ront. The

magnet on the other side has its South pole to the ront.The magnetic elds around these magnets push and pull the

electrons in the copper wire as the wire spins. The electrons in the

coil ow into transmission lines. These moving electrons are the

electricity that ows to our houses. Electricity moves through the

wire very ast. In just one second, electricity can travel around the

world seven times.

Other Ways to Produce ElectricityElectricity can also be produced in other ways. A solar cell turns

radiant energy into electricity. A battery turns chemical energy into

electricity.

A battery produces electricity using two diferent metals in a

chemical solution. A chemical reaction between the metals and the

chemicals rees more electrons in one metal than in the other. One

end o the battery is attached to one o the metals; the other end is

attached to the other metal. The end that rees electrons develops a

positive charge and the other end develops a negative charge. I a

wire is attached rom one end o the battery to the other, electrons

ow through the wire to balance the electrical charge.

A load is a device that does work or perorms a job. I a loadsuch

as a light bulbis placed along the wire, the electricity can do work

as it ows through the wire. In the picture to the right, electrons ow

rom the end o the battery, through the wire to the light bulb. The

electricity ows through the wire in the light bulb and back to the

battery.

CircuitsElectricity travels in closed loops, or circuits. It must have a complete

path beore the electrons can move. I a circuit is open, the electrons

cannot ow. When we ip on a light switch, we close a circuit. The

electricity ows rom the electric wire through the light and back

into the wire. When we ip the switch of, we open the circuit. No

electricity ows to the light.

GeneratorStator

Rotor Turbine Generator Shaft

Wicket

Gate

Tubine

Blades

Water

Flow

TURBINE GENERATOR

ELECTRICAL CIRCUITS

A closed circuit is a complete path allowing electricity

to ow from the energy source to the load.

ENERGY SOURCE

WIRES

LOAD

CLOSED SWITCH

An open circuit has a break in the path. There is no ow of

electricity because the electrons cannot complete the circuit.

ENERGY SOURCE

WIRES

LOAD

OPEN SWITCH


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When we turn a light switch on, electricity ows through a tiny

tungsten wire in an incandescent bulb. The wire gets very hot and

glows. When the bulb burns out, the tiny wire has broken. The path

through the bulb is gone.

When we turn on the TV, electricity ows through wires inside the

set, producing pictures and sound. Sometimes electricity runs

motors in items such as washers or mixers. Electricity does a lot o

work or us. We use it many times each day.

Measuring ElectricityElectricity makes our lives easier, but it can seem like a mysterious

orce. Measuring electricity is conusing because we cannot see it.

We are amiliar with terms such as watt, volt, and amp, but we do

not have a clear understanding o these terms. We buy a 60-watt

light bulb, a tool that needs 120 volts, or a vacuum cleaner that

uses 8.8 amps, and we do not think about what those units mean.

Using the ow o water as an analogy can make electricity easier

to understand. The ow o electrons in a circuit is similar to water

owing through a hose. I you could look into a hose at a given

point, you would see a certain amount o water passing that

point each second. The amount o water depends on how much

pressure is being appliedhow hard the water is being pushed. It

also depends on the diameter o the hose. The harder the pressure

and the larger the diameter o the hose, the more water passes

each second. The ow o electrons through a wire depends on

the electrical pressure pushing the electrons and on the cross-

sectional area o the wire.

VoltageThe pressure that pushes electrons in a circuit is called voltage.

Using the water analogy, i a tank o water were suspended one

meter above the ground with a one-centimeter pipe coming out

o the bottom, the water pressure would be similar to the orce oa shower. I the same water tank were suspended 10 meters above

the ground, the orce o the water would be much greater, possibly

enough to hurt you.

Voltage (V) is a measure o the pressure applied to electrons to

make them move. It is a measure o the strength o the current

in a circuit and is measured in volts (V). Just as the 10-meter tank

applies greater pressure than the 1-meter tank, a 10-volt power

supply (such as a battery) would apply greater pressure than a

1-volt power supply.

AA batteries are 1.5-volt; they apply a small amount o voltage

or pressure or lighting small ashlight bulbs. A car usually has a

12-volt battery; it applies more voltage to push current throughcircuits to operate the radio or deroster. The standard voltage o

wall outlets is 120 voltsa dangerous amount o voltage.

Electrical CurrentThe ow o electrons can be compared to the ow o water. The

water current is the number o molecules owing past a xed

point. Electrical current is the number o electrons owing past a

xed point. Electrical current (I) is dened as electrons owingbetween two points having a diference in voltage.

Current is measured in amperes or amps (A). One ampere is

6.25 X 1018 electrons per second passing through a circuit. With

water, as the diameter o the pipe increases, so does the amount

o water that can ow through it. With electricity, conducting wires

take the place o the pipe. As the cross-sectional area o the wire

increases, so does the amount o electrical current (number o

electrons) that can ow through it.

Water Tank

1 m

Water Tank

10 m

VOLTAGE

Water Tank

1 cm diameterpipe

Water Tank

10 cm diameterpipe

CURRENT



ResistanceResistance (R) is a property that slows the ow o electrons (the

current). Using the water analogy, resistance is something that

slows water owa smaller pipe or ns on the inside o the pipe.

In electrical terms, the resistance o a conducting wire depends on

which metal the wire is made o and its diameter. Copper, aluminum,

and silvermetals used in conducting wiresall have diferent

resistances.

Resistance is measured in units called ohms (). There are devicescalled resistors, with set resistances, that can be placed in circuits to

reduce or control the current ow.

Ohms LawGeorge Ohm, a German physicist, discovered that in many materials,

especially metals, the current that ows through a material is

proportional to the voltage. In the substances he tested, he ound

that i he doubled the voltage, the current also doubled. I he reduced

the voltage by hal, the current dropped by hal. The resistance o the

material remained the same.

This relationship is called Ohms Law, and can be written in threesimple ormulas. I you know any two o the measurements, you can

calculate the third using the ormulas to the right:

Electrical PowerPower (P) is a measure o the rate o doing work or the rate at which

energy is converted. Electrical power is the rate at which electricity is

produced or consumed. Using the water analogy, electrical power is

the combination o the water pressure (voltage) and the rate o ow

(current) that results in the ability to do work.

A large pipe carries more water (current) than a small pipe. Water at a

height o 10 meters has much greater orce (voltage) than at a height

o one meter. The power o water owing through a 1-centimeterpipe rom a height o one meter is much less than water through a

10-centimeter pipe rom 10 meters.

Electrical power is dened as the amount o electric current owing

due to an applied voltage. It is the amount o electricity required to

start or operate a load or one second. Electrical power is measured

in watts (W).

Water Tank

No

Resistance

Water Tank

Resistance

RESISTANCE

Water Tank Water Tank

POWER

OHMS LAW

Voltage = current x resistanceV=IxR or V=Ax

Current = voltage / resistanceI=V/R or A=V/

Resistance = voltage / currentR=V/I or =V/A

Power = voltage x currentP=VxI or W=VxA

ELECTRICAL POWER FORMULA

FORMULAS FOR MEASURING ELECTRICY

The ormula pie works or any

three variable equation. Put

your nger on the variable

you want to solve or and

the operation you need is

revealed.

E = I x R

I = E/R

R = E/I


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Electrical EnergyElectrical energy introduces time to electrical power. In the water

analogy, it would be the amount o water alling through the pipe

over a period o time, such as an hour. When we talk about using

power over time, we are talking about using energy. Using our

water example, we could look at how much work could be done by

the water in the time that it takes or the tank to empty.

The electrical energy that an appliance consumes can only be

determined i you know how long (time) it consumes electricalpower at a specic rate (power). To nd the amount o energy

consumed, you multiply the rate o energy consumption (measured

in watts) by the amount o time (measured in hours) that it is being

consumed. Electrical energy is measured in watt-hours (Wh).

Energy (E) = Power (P) x Time (t)or

E = P x tor

E = W x h = Wh

Another way to think about power and energy is with an analogy

to traveling. I a person travels in a car at a rate o 40 miles per hour

(mph), to nd the total distance traveled, you would multiply therate o travel by the amount o time you traveled at that rate.

I a car travels or 1 hour at 40 miles per hour, it would travel 40

miles.

Distance = 40 mph x 1 h = 40 miles

I a car travels or 3 hours at 40 miles per hour, it would travel 120

miles.

Distance = 40 mph x 3 hours = 120 miles

The distance traveled represents the work done by the car.

Electrical PowerWhen we look at power, we are talking about the rate that electrical

energy is being produced or consumed. Energy can be compared to

the distance traveled or the work done by the car. A person would

not say he took a 40-mile per hour trip because that is the rate.

He would say he took a 40-mile trip or a 120-mile trip. We would

describe the trip in terms o distance traveled, not rate traveled. The

distance is the work done.

The same applies with electrical power. You would not say you

used 100 watts o light energy to read your book, because watts

represents the rate you used energy, not the total energy used. The

amount o energy used would be calculated by multiplying the rateby the amount o time you read. I you read or ve (5) hours with

a 100-W bulb, or example, you would use the ormula as ollows:

Energy = Power x Time or E = P x t

Energy = 100 W x 5 h = 500 Wh

One watt-hour is a very small amount o electrical energy. Usually,

we measure electrical power in larger units called kilowatt-hours

(kWh) or 1,000 watt-hours (kilo = thousand). A kilowatt-hour is the

unit that utilities use when billing most customers.

The average cost o a kilowatt-hour o electricity or residentia

customers is about $0.11. To calculate the cost o reading with

a 100-W bulb or 5 hours, you would change the watt-hours into

kilowatt-hours, then multiply the kilowatt-hours used by the cost

per kilowatt-hour, as shown below:

500 Wh divided by 1,000 = 0.5 kWh

0.5 kWh x $0.11/kWh = $0.055

It would cost about ve and a hal cents to read or ve hours using

a 100-W bulb.



Water is ound in three orms: liquid, solid, and gas. The liquid orm

is water. The solid orm is ice. The gas orm is invisible and is called

water vapor. Water can change between these orms in six ways:

Freezing changes liquid water into ice.

Melting changes ice into liquid water.

Evaporation changes liquid water into water vapor.

Condensation changes water vapor into liquid water. For example,morning dew on the grass comes rom water vapor.

Sublimationchanges ice or snow into water vapor without passing

through the liquid state. The ice or snow seems to disappear

without melting rst.

Deposition changes water vapor into ice without the vapor

becoming a liquid rst. Water vapor alls to the ground as snow.

The Water CycleIn our Earth system, water is continually changing rom a liquid

state to a vapor state and back again.

Energy rom the sun evaporates liquid water rom oceans, lakes andrivers, changing it into water vapor.

As warm air over the Earth rises, it carries the water vapor into the

atmosphere where the temperatures are colder.

The water vapor cools and condenses into a liquid state in the

atmosphere where it orms clouds.

Inside a cloud, water droplets join together to orm bigger and

bigger drops. As the drops become heavy, they start to all. Clouds

release their liquid water as rain or snow. The oceans and rivers

are replenished and the cycle starts again. This continuous cycle is

called the water cycle or hydrologic cycle.

Characteristics of Water

Water is vital to lie on Earth. All living things need water to survive. Water covers 75 percent o

the earths surace. Our bodies are two-thirds water. Water is made o two elements, hydrogenand oxygen. Both are gases. Two atoms o hydrogen combine with one atom o oxygen to

create a molecule o water. The chemical ormula or water is H2O.

WatercoversmostoftheEarthssurface.

Image courtesy o NASA

SolarEnergy

Condensation(gas to liquid)

Precipitation(liquid or solid)

Evaporation(water vapor)

Evaporation(water vapor)

Oceans(liquid)

THE WATER CYCLE


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Water as an Energy SourceHydropowerHumans have used the power o moving water or more than 2,000

years. The rst reerences to water mills are ound in Greek, Roman,

and Chinese texts. They describe vertical water wheels in rivers and

streams. These traditional water wheels turned as the river owed,

turning millstones that ground corn.

By the 4th century AD, water mills were ound in Asia and northern

Europe. In the early 11th century, William the Conqueror noted

thousands o water mills in England. Most used stream and riverpower, but some worked with the tides.

Early water wheels were designed to allow water to ow beneath

the wheel. Later, millers diverted streams to ow over the tops o

the wheels. More recently, wheels were placed on their sidesa

more ecient method.

In the late 1700s, an American named Oliver Evans designed a mill

that combined gears, shats, and conveyors. Ater grain was ground,

it could be transported around the mill. This invention led to water

wheels being the main power source or sawmills, textile mills, and

orges through the 19th century.

In 1826, a French engineer, Jean-Victor Poncolet, designed an

enclosed water wheel so that water owed through the wheelinstead o around it. This idea became the basis o the modern

American water turbine.

In the mid 1800s, James Francis, Chie Engineer o the Locks and

Canal Company in Lowell, MA, designed a water turbine with

curved blades. Known as the Francis turbine, modern variations o

this water turbine are still in use today in hydropower plants.

Generating electricity rom hydropower began in the United

States on July 24, 1880, when the Grand Rapids Electric Light and

Power Company used owing water to power a water turbine to

generate electricity. It created enough power to light 16 lamps in

the Wolverine Chair Factory. One year later, hydropower was used

to light all the street lamps in the city o Niagara Falls, NY.

Dams Yesterday and TodayThe oldest known man-made dams were small structures built

over 5,000 years ago to divert river water to irrigate crops in

Mesopotamia. In 2900 BC, Egyptians in the city o Memphis built a

dam across the Nile River. The dam stopped periodic ooding and

created a reservoir or irrigation and drinking water.

The Romans also built many dams in the rst millennium, but

most o their technical knowledge and engineering skills were lost

during the all o the Roman Empire. Dams did not become major

civil projects until the end o the 19 th century when the need or

large dams coincided with the ability to build them.

Today, there are more than 500,000 dams worldwide. Most dams

are small structures less than three meters high. There are about

40,000 large dams that measure higher than 15 meters.

There are about 80,000 dams in the United States, but less than

three percent (2,400) include power plants used to generate

electricity. The rest were built or recreation, shing, ood control,

crop irrigation, to support the public water supply, or to make

inland waterways accessible to ships and barges. Power plants with

turbines and generators could be added to some o these dams to

produce electricity.

Amid-nineteenthcenturywaterwheel.

WorkersinstallaFrancisturbineatGrandCouleeDam,1947.

AFrancisturbinefeaturescurvedblades.

Image courtesy o U.S. Bureau o Reclamation



Types of DamsA dam is either an overow or non-overow dam. An overow

dam allows water to spill over its rim. A non-overow dam uses

spillwayschannels going through or around the damto control

the amount o water behind the dam. This also allows a dam

operator to channel water to a hydropower plant when it is needed.

Dams are also categorized by the materials used in their construction

and by their shape. Most dams are made o Earth and clay, gravel,

rock, stone masonry, wood, metal, or concrete.A gravity dam uses only the orce o gravity to resist water

pressure. It holds back the water by the sheer orce o its mass

pressing downward. A gravity dam is built wider at its base to ofset

the greater water pressure at the bottom o the reservoir. Most

gravity dams are made o concrete. The Hoover Dam is an example

o a concrete arch gravity dam (See page 16 for the story of how the

Hoover Dam was built).

An embankment dam is a gravity dam made o rocks and dirt, with

a dense, water-resistant center that prevents water rom seeping

through the dam. The slopes o the dam are atter on both sides,

like the natural slope o a pile o rocks.

Like a gravity dam, an embankment dam holds back water by theorce o gravity acting on its mass. An embankment dam requires

much more material to build than a gravity dam, since rock and

Earth are less dense than concrete.

An arch dam can only be built in a narrow river canyon with solid

rock walls. It is built rom one wall o a river canyon to the other and

curves upstream toward the body o a reservoir. The curved shape

diverts some o the immense orce o the water toward the canyon

walls.

An arch dam is built o stone masonry or concrete and requires less

material than a gravity dam. It is usually less expensive to build.

The Glen Canyon Dam, spanning the Colorado River in Arizona, is

the tallest arch dam in the U.S. It is 216 meters (710 eet) high. It was

opened in 1966 to provide water storage or the arid U.S. Southwest

and to generate electricity or the regions growing population.

A buttress dam consists o a relatively narrow wall that is supported

by buttresses (triangle-shaped supports) on the downstream side.

Most buttress dams are made o concrete reinorced with steel.

Thick buttresses help the dam withstand the pressure o water

behind it. While buttress dams use less material than gravity dams,

they are not necessarily cheaper to build. The complex work o

orming the buttresses may ofset the savings on construction

materials. A buttress dam is desirable in a location that cannot

support the massive size o a gravity dams oundation.

GRAVITY DAM

EMBANKMENT DAM

ARCH DAM

BUTTRESS DAM


15/64


A Hydropower PlantThere are three main parts o a typical hydropower plant: the

reservoir, the dam, and the power plant (turbines and generators).

The reservoir stores the water (potential energy). The dam contains

the water with openings in the dam controlling the waters ow. The

power plant (turbine and generator) converts the kinetic energy in

the moving water into electricity.

A reservoir holds water behind the dam to create a greater distance

between the water in the reservoir and the river below. The distancethe water drops rom the reservoir to the turbine is the head; the

higher the drop, the greater the head. The amount o moving water

is called the ow; more ow equals more orce. The mass o the

water in the reservoir exerts pressure to move the water; the greater

the mass, the greater the pressure.

The generation o electricity begins with water owing rom

the reservoir into openings on the upstream side o the dam to

penstocks, which are very large pipes. The water ows down the

penstocks to turbines at the bottom, spinning the turbines to

power the generators. The generators produce electricity, which is

sent to transmission lines where it begins its journey to consumers.

The water that entered the penstocks returns to the river below the

dam and continues its downstream journey.

Electricity from HydropowerAlmost 20 percent o the worlds electricity is produced by

hydropower. In the Northern Hemisphere, Canada produces 59

percent o its electricity rom hydropower, while Mexico produces

13 percent. In the United States, 7-10 percent o electricity comes

rom hydropower, depending on the supply o water. That is enough

power to supply 28 million households.

HYDROPOWER DAM

RIVER

SWITCHYARD

view from above

MAGNETS

COPPER COILS

ROTATINGSHAFT

1. Water in a reservoir behind a hydropower dam ows through a large intakescreen, which lters out large debris, but allows sh to pass through.

2. The water travels through a large pipe, called a penstock.

3. The force of the water spins a turbine at a low speed, allowing sh to passthrough unharmed.

4. Inside the generator, the shaft spins coils of copper wire inside a ring ofmagnets. This creates an electric eld, producing electricity.

5. Electricity is sent to a switchyard, where a transformer increases the voltage,

allowing it to travel through the electric grid.

6.Water ows out of the penstock into the downstream river.

GENERATOR

GENERATOR

TURBINE

RESERVOIR

IntakeDAM

PENSTOCK

DETA

IL

1

2

3

4

5

6

GENERATORS AT A HYDROPOWER PLANT

ThegeneratorsattheSafeHarborhydropowerplantinsouthernPennsylvania.

0.6

%5.9

%

48.5

%

19.6

%

21.3

%

1.4

%

1.3

%

0.4

%

Coal

NaturalGas

Uranium

Hydropower

Biomass

Wind

Geothermal

Other

RENEWABLENON-RENEWABLE

50%

40%

30%

20%

10%

0%

1.1

%

Petroleum

Data: EIA

U.S. ELECTRICITY PRODUCTION, 2008

Norway

Brazil

Canada

Switzerland

Vietnam

India

Mexico

China

Egypt

United States Data: EIA, 2008

98%

87%

69%

61%

41%

19%

19%

17%

13%

7%

The percentage ofelectricity that is consumedfrom hydropower inselected countries.

HYDROPOWER AROUND THE WORLD



Hoover Dam is located in Black Canyon on the Colorado River, about

30 miles southeast o Las Vegas, NV. It was authorized by Congress

in 1928 to provide electricity, ood control, and irrigation or the

arid Southwest. It was built in the early 1930s at the height o the

Great Depression, providing much needed jobs or thousands o

workers.

Hoover Dam is a concrete arch gravity type dam, in which the power

o the water is held back by the orce o gravity, as well as the arch

shape. It is 726.4 eet tall rom the oundation rock to the roadway

on the crest o the dam. There are towers and ornaments that rise 40

eet above the crest and weigh more than 6,600,000 tons.

Beore construction o the dam itsel could begin, the Colorado River

had to be diverted around the construction site. Four concrete-

lined tunnels (each 50 eet in diameter and 4,000 eet long) were

drilled through the canyon walls, two on each side o the canyon.

Then temporary earthen coferdams were built above and below

the site to channel the river water through the tunnels and protect

the construction site.

When the diversion tunnels were no longer needed, the upstream

entrances were closed by huge steel gates and concrete plugs were

placed in the middle o the tunnels. Downstream sections o the

tunnels are used as spillways or the dam. The temporary coferdams

were torn down once the dam was completed.

There are 4,360,000 cubic yards o concrete in the dam, power plant,

and other structures necessary to the operation o the dam. This

much concrete would build a tower that is 100 eet square and 2

miles high, or pave a standard highway that is 16 eet wide rom San

Francisco to New York Citya distance o more than 2,500 miles.

Setting the concrete produced an enormous amount o heat. The

heat was removed by placing more than 582 miles o 1-inch stee

pipe in the concrete and circulating ice water through it rom a

rerigeration plant that could produce 1,000 tons o ice in 24 hours

It took ve years to build the dam, power plant, and othe

structures. During construction, a total o 21,000 men worked onthe daman average o 3,500 men daily. A total o 114 men died

during construction o the dam, but none is buried in the concrete

although stories to that afect have been told or years.

Beore construction o the dam could begin, the ollowing projects

were necessary:

the construction o Boulder City to house the workers;

the construction o seven miles o highway rom Boulder City

to the dam site;

the construction o 22.7 miles o railroad rom Las Vegas to

Boulder City and an additional 10 miles rom Boulder City to the

dam site; and the construction o a 222-mile-long power transmission line

rom Caliornia to the dam site to supply energy or construction

Once the dam was completed and the Colorado River was contained

a reservoir ormed behind the dam called Lake Mead, which is an

attraction to boaters, swimmers, and shermen. The Lake Mead

National Recreation Area is home to thousands o desert plants and

animals that adapted to survive in an extreme place where rain is

scarce and temperatures soar.

Summarized from the U.S. Bureau of Reclamation, U.S. Department of the Interior

website: www.usbr.gov/lc/hooverdam/faqs/damfaqs.html.

Building Hoover Dam: Transforming the Desert Southwest


17/64


Types of HydropowerHydropower acilities can be categorized into two main types:

conventional and pumped storage. Conventional projects

account or over 80 percent o hydropower generation in the U.S.

Conventional hydropower plants use the available water rom

rivers, streams, canal systems, or reservoirs to produce electrical

energy.

Some conventional projects include reservoirs and some do not.

Projects with dams and reservoirs, known as impoundmentfacilities, store water and use it to generate electricity when there

is the demand.

Projects without reservoirs are known as diversion acilities or run-

o-river projects. Diversion projects do not require dams; instead,

a portion o a river is diverted or channeled through a canal or

penstock. Electricity rom the Canadian side o Niagara Falls is

generated through a diversion acility.

Run-of-river projects have turbines installed in ast-owing

sections o the rivers, but they do not signicantly slow down the

rivers ow. The ow o water at run-o-river and diversion projects

continues at about the same rate as the natural river ows.

Pumped Storage PlantsAnother type o hydropower plant is known as a pumped storage

plant. A pumped storage plant circulates water between two

reservoirsone higher than the other. When the demand or

electricity is low, the plant uses electricity to pump water to the

upper reservoir and stores the water there until it is needed.

When there is a high demand or electricity, the water is released

rom the upper reservoir to ow through turbines and back into the

lower reservoir to quickly generate electricity.

A pumped storage plant is in many ways like a huge battery that

stores the potential energy o the water in the upper reservoir untilthere is a demand or electricity, which it can generate very quickly

by releasing the water.

RUN-OF-RIVER PROJECT

Image courtesy o U.S. Army Corps o Engineers

PUMPED STORAGE PLANT


NIAGARA FALLSNiagara FallsNatural WonderNiagara Falls produces one quarter o Ontarios electricity, but the

hydropower does not come directly rom the alls. Rushing water

is diverted rom the Niagara River, upstream rom the alls, to a

powerhouse. There the water drops 120 eet through penstocks.

The rushing water provides energy to turbines at the bottom,

spinning shats that are three eet in diameter and attached to the

generators, which rotate 250 times a minute to produce electricity.

Ater the water ows past the turbines, it runs through a tunnel and

empties back into the river.

ChiefJosephDamontheColumbiaRiverinWashington.

SenecaPumpedStorageGeneratingStationaboveKinzuaDamontheAlleghenyRiverinWarrenCountynearWarren,PA.



Maneuvering Around a DamThe impact o dams on the migration o sh, especially spawning

salmon and steelhead in the Northwest, is an important issue

today. Some dams have sh ladders built in to allow sh to migrate

upstream to spawn. Fish ladders are a series o small pools arranged

like stair steps. The sh jump rom pool to pool, each pool higher

than the one beore, eventually bypassing the dam.

When the sh swim downstream to return to the ocean, they need

to bypass the dam again. Headed downstream, sh are divertedaround dams through spillways.

Navigation DamsDams to produce electricity are not the only dams built across

rivers. Navigation dams are built to make sure there is enough water

or boats and barges as they travel up and down rivers.

When a dam is built across a river that is used by boats and barges,

a canal is dug adjacent to the dam or the boats to use. The boats

bypass the dam through locks in the canal. Each lock has large

upstream and downstream doors that can be opened and closed.

A boat traveling upstream is moving rom a lower water level to ahigher water level. When the boat enters a lock, the doors are closed

and water is let in so that the water level in the lock rises. The boat

rises with the water until it is level with the upstream water level.

The upstream door opens, and the boat moves on to the next lock.

A boat may need to go through several locks beore it reaches the

river on the other side o the dam.

Hydroelectric Power Plant SafetyThe purpose o a dam is to contain a large amount o water that

could cause major destruction downstream i the dam ails, so

saety is an important issue. Some dams have ailed in the past,

but large dam ailure is not considered a signicant threat today.The major dams in use today were designed by engineers to last

or generations, and to withstand Earthquakes, oods, and other

potential hazards.

Dams are required by law to be monitored continuously and

inspected routinely or potential saety problems. State and ederal

agencies, as well as dam owners, are involved in the process. Security

procedures against terrorist attacks have also been put into place.

Federal RegulationThe Federal Energy Regulatory Commission (FERC) is the

ederal agency that oversees all non-ederal hydropower plants on

navigable waterways and ederal lands. FERC is in charge o licensing

new plants and relicensing older plants when their licenses expire.

FERC is charged with ensuring that all hydropower plants minimize

damage to the environment. Many concerns about relicensing

involve natural resource issues. Hydropower projects generally

alter natural river ows, which may afect sh populations and

recreational activities, both positively and negatively. New

construction or expansion may also afect wildlie habitat, wetlands,

and cultural resources. People who live downstream o the projects

also want to be assured that the dams are sae.

FISH LADDER

Image courtesy o Bonneville Power Administration

NAVIGATION DAM


TheshladderatBonnevilleDamontheColumbiaRiverinthePacicNorthwest.

AnaerialviewoftheSooLocksandtheInternationalBridgeatSaultSteMarie,MI.

SAFETY INSPECTIONS

Image courtesy o Tennessee Valley Authority

AnengineeronTVAsRopeAccessTeaminspectsoneofthefourspillwaygatesatFontanaDam.


19/64


Advantages and DisadvantagesUsing hydropower as an energy source has many advantages over other energy sources, but hydropower has signicant disadvantages too

because o its impact on the environment.

Advantages of HydropowerHydropower is a clean energy source. It is ueled only by moving

water, so it does not produce emissions. Hydropower does not

increase the level o greenhouse gases in the atmosphere.

Hydropower is a renewable energy source. The total amount o

water in a hydropower system does not change; the moving water

is used to generate electricity and returned to the source rom

which it came.

Hydropower is usually available when it is needed. Engineers can

control the ow o water through the turbines to produce electricity

on demand as well as the amount o electricity generated.

Hydropower is an established, proven, and domestic source o

energy produced in the United States.

Hydropower is an economical way to produce electricity.

Maintenance costs o hydropower acilities are low. Once a plant is

up and running, the water ow that powers it is ree. The electricity

generated by hydropower acilities is the cheapest electricity in

the country.

Hydropower is an ecient way to produce electricity. The average

hydropower plant is about 95 percent ecient at converting the

energy in the moving water into electricity.

Dams create reservoirs that ofer a wide variety o nonenergy

benets to communities, such as recreational shing, swimming,and boating. The reservoirs can also increase the property value o

the adjacent land.

Hydropower acilities can help manage the water supply, providing

ood control and a reliable supply o drinking water during

drought. Many dams were built or ood control. The power plants

were an additional benet.

Hydropower dams are very sae and durablebuilt to last or

hundreds o years.

Hydropower is a exible energy source in meeting electricity

generating needs quickly. Hydropower plants can begin generating

electricity within minutes o increased demand. Most hydropowe

plants can also provide reliable and dependable baseload power.

Only three percent o existing dams in the U.S. contain generators

Without building any new dams, existing dams have the potentia

to generate 23,000 MW o power, enough electricity or over 6

million households.

Disadvantages of HydropowerHydropower plants are dependent on water supply. When there

is a drought, or example, hydropower plants cannot produce asmuch electricity.

Hydropower dams on rivers permanently change the natura

ecology o large areas o land, upstream and downstream. When

a dam is built, the resultant reservoir oods large areas o land

upstream rom the dam. The natural ecology o the river and

adjacent land downstream is changed by a reduction in soi

deposition.

Hydropower dams can impact water quality and ow. Reservoirs

can have low dissolved oxygen levels in the water, a problem

that can be harmul to sh and downstream riverbank habitats

Maintaining water ow downstream o a dam is also critical or the

survival o habitats.Some sh populations, such as salmon, migrate upstream to reach

spawning grounds. Dams can block sh rom completing this

natural migration process. Fish ladders may be built to help sh

swim upstream.

Development o new hydropower resources can be very expensive

because dams have been built at many o the more economica

locations. New sites must compete with other potential uses o the

land.

Thedown-riversideoftheSafeHarborhydropowerplantinsouthernPennsylvania.



The Tennessee Valley Authority (TVA) is a public utility established by

Congress in 1933 as one o Franklin Roosevelts solutions to the Great

Depression. The Tennessee Valley was in bad shape in 1933. Much o the

land had been armed too hard or too long, depleting the soil. The best

timber had been cut. TVA developed ertilizers, taught armers how to

improve crop yields, and helped replant orests, control orest res, and

improve habitat or wildlie and sh.

The most dramatic change in Valley lie came with the advent o

electricity generated by TVA dams that also controlled oods andimproved navigation. Electricity brought modern amenities to

communities and drew industries into the region, providing desperately

needed jobs.

During World War II, the country needed more electricity and TVA

engaged in one o the largest hydropower construction programs ever

undertaken in the United States. At the programs peak in 1942, twelve

hydropower projects and a steam plant were under construction at the

same time, employing 28,000 workers. By the end o the war, TVA had

completed a 650-mile navigation channel the length o the Tennessee

River and had become the nations largest electricity supplier.

Today, TVAs system consists o a mix o energy sources, including:

29 hydroelectric dams and 1 pumped storage plant;

11 coal-red and 8 combustion-turbine power plants;

3 nuclear power plants;

16 solar power sites;

1 wind-power site; and

1 methane gas site.

TVA operates a system o 49 dams and reservoirs on the 652-mile-long

Tennessee River and its tributaries, as well as managing 293,000 acres

o public land. TVA manages the complete river system as an integrated

unit to provide a wide range o benets, including:

year-round navigation;

ood control;

electricity generation;

recreational opportunities;

improved water quality; anda reliable water supply to cool power plants and meet municipal and

industrial needs.

The Tennessee Valley Authority: A Vision Born from Hydropower

PresidentFranklinD.RooseveltsignstheTVAActin1933.

Right:ThededicationoftheDouglasDaminDandridge,TN,1943.

TheFontanaDaminNorthCarolinaasitnearscompletionin1944.

Images courtesy o Tennessee Valley Authority


21/64

TheNEEDProjectP.O.Box10101,Manassas,VA201081.800.875.5029www.NEED.org 2

A Case Study in Removing a Small Dam

When the Costs Outweigh the BenetsIn May 1999, Portland General Electric (PGE) announced plans to

decommission (tear down) its 95-year-old hydropower project on

the Sandy River in Oregon. The project will eliminate expensive

maintenance costs to the power plant and avoid the cost o bringing

sh protection up to todays standards. The project consists o

dismantling the ollowing:the 47-oot-high Marmot Dam;

a concrete-lined canal that takes water rom Marmot Dam to

the Little Sandy River;

the 16-oot-high Little Sandy Dam;

a 15,000-oot-long wooden ume (articial water channel); and

a 22-megawatt powerhouse.

Marmot Dam was removed in 2007, restoring the Sandy to a ree-

owing river or the rst time in nearly a century. Within hours

the Sandy River looked like a natural river. Torrents o water carried

sediment downstream, helping create natural bends, bars, and

logjams. The Little Sandy Dam was removed in 2008.

PGE is giving about 1,500 acres o land to the Western Rivers

Conservancy. This land will orm the oundation o a natural

resource and recreation area in the Sandy River Basin. Covering

more than 9,000 acres, the area will be owned and managed by the

U.S. Bureau o Land Management.

BEFORE DEMOLITION

DURING DEMOLITION

Images courtesy o U.S. Geological Survey

A Case Study in Improving Ecology at a DamObservers in the Grand Canyon o the Colorado River have noticed

a decline in the number o sandbars used as campsites. This decline

is attributed to Glen Canyon Dam, which controls the ow o the

Colorado through the canyon. Most o the sediment and sand now

gets trapped behind the dam.

The rapids that make the

Grand Canyon so popular with

white-water raters are created

by debris anspiles o rock

ragmentsthat tumble down

rom tributaries during intense

rainall. The debris ans used to

be cleaned out yearly by oods

o water that owed through the

canyon during spring snowmelt

in pre-dam years.

The dam dramatically reduced

the ow o water through the

canyon. This drop in water ow limits the ability o the river to move

rock debris. In the absence o oods, there will be a continuingbuildup o boulders and smaller rocks on many rapids, which could

become more dangerous to navigate. Elimination o yearly ooding

also allowed silt to build up in backwater channels, leading to the

extinction o our native sh.

The U.S. Bureau o Reclamation, which operates Glen Canyon Dam,

released an unusually high ow o water during the spring o 1996

to see i it could rebuild beaches and restore other habitats that

have deteriorated since the dams completion in 1963. Two other

high ows were released in November 2004 and March 2008.

I scientists nd that periodic ooding is successul at rebuilding

the sandbars, maintaining the rapids, and reducing sediment in

upstream tributaries, it will become a part o long-term plans orthe operation o the dam.

HIGH FLOW

Image courtesy o U.S. Geological Survey

Rapidsarecausedbylargebouldersthatgetstuckontheriverbed.



New Hydropower InitiativesThe mission o the U.S. Department o Energy (DOE) Hydropower

Program is to:

conduct research to improve the benets o hydropower; and

develop new technologies to increase hydropower capacity.

One DOE initiative promotes upgrades at existing hydropower

plants to increase their eciency and capacity. Upgrades will

include replacing old turbines and generator parts with more

ecient equipment, ne-tuning the perormance o existing

equipment, and automating operations.

Upgrades that involve only eciency increases have little

environmental impact and provide benets such as ewer sh

deaths and improved water quality. Upgrades that increase

capacity by adding turbines or raising the height o the reservoir

have greater potential to impact the environment.

The DOE plan also includes retrotting (adding power plants to)

existing dams to generate electricity. Since only three percent o

the dams in the U.S. have power plants, there are opportunities

to add them to many existing dams, including storage and ood

control dams, and navigation dams. Most environmental impacts

have already occurred as a result o construction and operation o

the dams.

The increased electricity provided by the DOE initiative could

replace 18 large (500 MW) coal-red power plants, reducing carbon

dioxide emissions.

New Turbine SystemsThe Department o Energy also supports research into new

technologies. Hydropower plants can cause injuries or death to sh

and impact water quality. New hydropower turbine technologies

could minimize these efects. Benets o new turbine technologies

include:

reduced sh mortality;

improved water quality; and

reduction in carbon dioxide (CO2) emissions.

FISH-FRIENDLY TURBINE

FISH BYPASS

Images courtesy o Grant County Public Utility District

Image courtesy o Alden Lab

AttheWanapumDamontheColumbiaRiver,ash-friendlyturbinerunnerthatisdesignedtohelpsalmonsmoltspassthroughtheturbinewithoutinjuriyisbeingtested.

Right:Across-sectionofash-friendlyturbine.

Alden LabFounded in 1894, Alden Lab is the oldest hydraulic laboratory in

the United States and one o the oldest in the world. Alden has

developed a new hydraulic turbine runner to reduce sh injury

and death as part o the DOE program. Results o pilot-scale tests

indicate that sh survival through the turbine would be 94-100

percent. Studies are being planned or a hydropower site.


23/64


Energy from the TidesNear shore, the ocean rises and alls with the tides. Tides contain

an enormous amount o energy. Some power stations harness the

energy in the changing tides to generate electricity.

Tides are caused by the gravitational orces between the Earth and

moon. The moon pulls on the ocean water that is closest to it. This

creates a bulge in the surace o the water, called a tidal bulge.

Because the Earth is rotating, the water on the opposite side o the

Earth also orms a tidal bulge. These bulges produce high tides.Between the tidal bulges is lower water that produces low tides.

Tidal BarrageA tidal power station, or tidal barrage, is built across an estuary,

the area where a river runs into the ocean. The water here rises and

alls with the tides.

A tidal barrage is like an underwater ence with gates and turbines

held in a caisson, a supporting structure. As the tide rises, the water

ows through the barrage, spinning the turbines, then collects in

the estuary. When the tide drops, the water in the estuary ows

back to the ocean. The water again turns the turbines, which are

built to generate electricity when the water is owing into and outo the estuary.

Tidal Stream PowerAnother source o tidal power relies on strong, steady ocean

currents. This technology is known as tidal stream power.

Underwater turbines can be installed in the ocean in places with

strong tidal currents or steady ocean currents.

Marine Current Turbines Ltd, based in Bristol, England, has developed

the worlds largest tidal stream system, known as SeaGen. A SeaGen

device is operating in Strangord Lough (a shallow bay situated on

the east coast o Northern Ireland). The turbine regularly delivers

1.2 MW to the Northern Ireland grid.

The SeaGen consists o two large rotors, each driving a generator.

The twin rotors are mounted on wing-like extensions on either side

o a steel tower that is set into a hole drilled in the sea oor.

New York Citys East River ProjectThe city and state o New York have partnered with Verdant Power

to harness the energy in the ebb and ow o the tides in Manhattans

East River. The Roosevelt Island Tidal Energy (RITE) Project is planning

to install a kinetic hydropower system o 100-300 tidal turbines

anchored on the bottom o the river. The project could generate

up to 10 MW o electricity. Monitoring o the six initial turbines was

completed in 2008. Evaluatedor perormance and or

environmental impact, the rst

stage was deemed a success.

Verdant Power is now moving

orward with the next stage o

development.

TIDAL BULGE

EARTH

MOON

Gravitational Attraction

Ro

ta

tio

noftheEarth

NEART

IDAL

BU

LGEFA

RTIDA

LBULGE

TIDAL BARRAGE

TIDAL FLOW

DIRECTIONDAM

TURBINE

Tidal water is captured at high tide behind a

dam. When the tide turns, the water is released

to the sea, passing through a set of turbines.

TIDAL STREAM POWER

Image courtesy o SeaGen

AnartistsrenderingoftheSeaGentidalstreamsystem.

FreeFlowSystemturbinebeinginstalledinEastRiver,NY.

Image courtesy o Verdant Power



WavesOcean waves are caused mainly by wind. The size o waves depends

on the speed o the wind, wind duration, and the distance o water

over which the wind blows. Usually, the longer the distance the

wind travels over water or the harder it blows, the higher the waves.

Winds o 30 miles per hour can cause 15-oot waves. Very strong

winds can cause waves 40-50 eet high.

As the wind blows over the water, there is riction between the wind

and the surace o the water. The wind pulls the surace water inthe direction it is going. The water is much denser than the air and

cannot move as ast, so it rises, and then it is pulled back down by

the orce o gravity. The alling waters momentum moves it below

the surace, and water pressure rom below pushes it up again.

This tug o war between gravity and water pressure creates wave

motion.

Ocean waves are, thereore, the up and down motion o surace

water. The highest point o a wave is the crest; the lowest point is

the trough.

The height o a wave is the distance rom the trough to the crest.

The length o a wave is the distance between two crests. Waves

usually ollow one another, orming a train. The time it takes twocrests in a train to pass a stationery point is known as the period o

a wave. Wave periods tell us how ast the waves are moving.

Harnessing Wave EnergyThe energy in waves can be harnessed to generate electricity.

Studies show that waves of the coasts o Oregon and Washington

have good potential or generating electricity.

There are two main types o wave energy generation devices,

xed and oating. Fixed devices are built into clifs along a coast.

One xed device is the oscillating water column. The column, or

chamber, is partially submersed in the water. As the waves ow in

and out o the chamber, the air inside the chamber is compressed

and decompressed. The orced air spins a turbine. The generatorattached to the turbine produces electricity.

Another xed device is a tapered channel (TAPCHAN) system. I t

consists o a channel connected to a reservoir in a clif. The channel

gets narrower as it nears the reservoir, causing the waves to increase

in height.

When the waves are high enough, they spill over the top o the

channel into the reservoir. The stored water ows out o the

reservoir through a turbine, generating electricity.

The TAPCHAN system is not useable in all coastal areas. Ideal

locations have consistent waves, good wave energy, and a tidal

range o less than one meter.

WAVE MEASUREMENTS

CREST LENGTH

TROUGH

HEIGHT

TAPCHAN SYSTEM

RESERVOIR

TURBINEHOUSING

OCEAN

CLIFF FACE

TAPERED

CHANNEL

OSCILLATING WATER COLUMN

CHAMBER

Wave

VENT T URBI NE WAVE

Air pushed

through by

incoming wave

VENT TURBINE

CHAMBER

WAVE

CLIFF FACE

Wave

VENT T URBI NE WAVE

CHAMBER

Air pulled backas wave

retreats


25/64


ATTENUATOR

FLOATING TUBES

JOINTS

Virtual Hydropower

ProspectorDeveloped by the Idaho

National Laboratory, this online

geographic inormation system

(GIS) tool is designed to assist

you in locating and assessing

natural stream water energy

resources in the United States.

Users can view data regarding

hydropower projects across theUnited States including:

Water Energy Resource Sites

Potential Projects

Hydrography

Power Systems

Transportation

Areas and Places

Land Use

SEAGEN ATTENUATORS

Image courtesy o SeaGen

AnartistsrenderingoftheSeaGentidalstreamsystem.

TheVirtualHydropowerProspector:http://hydropower.id.doe.gov/prospector/index.shtml

Floating DevicesSeveral oating wave devices are also under development. They

generate electricity as they are moved by the motion o waves.

One such device, called an attenuator, is a series o our tubes

that are linked together with hinged joints. Passing waves cause

each tube to rise and all like a giant sea snake. The motion tugs

at the joints linking the tubes. The joints act as a pumping system,

pushing high pressure oil through a series o motors that drive the

generators to produce electricity. The wave energy devices will beconnected to the seaoor by transmission lines.

Future of HydropowerThe uture o hydropower includes both challenges and

opportunities, and it will continue to be a major part o the U.S.

and global energy mix or many years. As the nation and the world

develop strategies to deal with global climate change, hydropower

will play a signicant role by producing clean, economical electricity

without carbon dioxide emissions.

Advances in turbine design and other mitigation strategies will

continue to reduce the impact o conventional hydropower acilities

on sh populations, water quality, and the environment. New

technologies will also allow acilities to become more ecient and

generate more electricity. The addition o power plants to existing

dams will increase the overall capacity o the hydropower industry.

The development and implementation o technologies that harness

the power o moving water, whether it is rom ree-owing streams,

the tides, ocean currents, or waves, will also contribute to the uture

o hydropower in the United States and the world.



B.C. Hydropower used by the Greeks to turn water wheels or grinding grains more than 2,000 years ago.

Mid-1770s French hydraulic and military engineer Bernard Forest de Blidor wrote Architecture Hydraulique, a our-

volume work describing vertical- and horizontal-axis machines.

1775 U.S. Army Corps o Engineers ounded, with establishment o Chie Engineer or the Continental Army.

1879 The rst hydroelectric plant was built in the U.S. at Niagara Falls.

1880 Michigans Grand Rapids Electric Light and Power Company, generating electricity by dynamo belted to a

water turbine at the Wolverine Chair Factory, lit up 16 brush-arc lamps.

1881 Niagara Falls city street lamps powered by hydropower.

1882 Worlds rst hydroelectric power plant began operation on the Fox River in Appleton, WI.

1886 About 45 water-powered electric plants in the U.S. and Canada.1887 San Bernardino, CA opens rst hydroelectric plant in the west.

1889 Two hundred power plants in the U.S. use waterpower or some or all generation.

1901 First Federal Water Power Act. No one could build or operate a hydroelectric plant on a stream large

enough or boat trac without special permission rom Congress.

1902 U.S. Bureau o Reclamation established.

1907 Hydropower provided 15 percent o U.S. electrical generation.

1920 Hydropower provided 25 percent o U.S. electrical generation. Federal Power Act establishes Federal

Power Commission authority to issue licenses or hydro development on public lands.

1933 Tennessee Valley Authority was established, taking charge o hydroelectric potential o the Mississippi

River in the Tennessee Valley.

1935 Federal Power Commission authority extended to all hydroelectric projects built by utilities engaged in

interstate commerce.

1936 Hoover Dam began operating on the Colorado River. Using multiple Francis turbines, the Hoover Dam

plant produces up to 130,000 kilowatts o power.

1937 Bonneville Dam, the rst Federal dam, begins operation on the Columbia River. Bonneville Power

Administration established.

1949 Hydropower provided almost 33 percent o the nations electrical generation. Conventional capacity

tripled in United States since 1920.1977 Federal Power Commission disbanded by Congress. A new agency was created, the Federal Energy

Regulatory Commission (FERC).

1980 Conventional hydropower plant capacity nearly tripled in United States since 1940.

Today Between 710 percent o U.S. electricity comes rom hydropower, depending on water supply. In total,

the U.S. has about 80,000 MW o conventional capacity and 18,000 MW o pumped storage capacity.

History of Hydropower Timeline


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Careers in the Hydropower Industry

Energy Industry Analysts assess the signicance o developments

and trends in the energy industry and use this inormation or current

and uture regulatory policies. Energy industry analysts require

a degree in nance, management, or other business, industrial,

mechanical or other engineering eld.

Accountants establish accounting policy, providing guidance to

energy companies or reporting issues.

Auditors review nancial inormation about energy companies

to ensure they are in compliance with government regulations.

Accountants and Auditors require a bachelors degree in accounting.

Administratorsprovide general oce clerical support to proessional,

program, or technical staf members utilizing typing skills and a

knowledge o oce automation hardware and sotware systems.

Administrative support staf may be responsible or timekeeping,

government procedures and other personnel matters.

Communications Professionals must possess excellent writing and

speaking skills, a customer service attitude and the ability to respond

quickly in a dynamic environment. Communications proessionals

require a bachelors degree in communications or English.

Economists closely ollow and analyze trends in the various energy

industries to make sure a healthy competitive market is in place. They

consult with experts in energy economics, market design, anti-trust

and other issues, and use economic theory on real-world problems

and situations. Economists require a bachelors degree in economics.

Hydrologists research the distribution, circulation, and physical

properties o underground and surace waters, and study the

orm and intensity o precipitation, its rate o inltration into thesoil, movement through the earth, and its return to the ocean and

atmosphere.

Hydrologists apply scientic knowledge and mathematical principles

to solve water-related problems in societyproblems o quantity,

quality, and availability. They may be concerned with nding water

supplies or cities and irrigated arms, or controlling river ooding

and soil erosion. They may also work in environmental protection

preventing or cleaning up pollution and locating sites or sae

disposal o hazardous wastes. The work o hydrologists is as varied

as the uses o water and may range rom planning multimillion dollar

interstate water projects to advising homeowners about backyard

drainage problems.

A bachelors degree is adequate or entry-level positions. Students

who plan to become hydrologists should take courses in the physical

sciences, geophysics, chemistry, engineering science, soil science,

mathematics, computer science, aquatic biology, atmospheric

science, geology, oceanography, hydrogeology, and the management

or conservation o water resources. In addition, some background

in economics, public nance, environmental law, and government

policy is needed to communicate with experts in these elds.

Information Technology Specialists do systems programming, of-

the-shel sotware management, database administration, network

and telecommunications operations/administration, security

implementation, disaster recovery, electronic ling, and customer

service support. Inormation Technology specialists require a

bachelors degree in Inormation Technology.

Power Plant Operators control machinery that makes electric power

They control and monitor boilers, turbines, and generators and adjus

controls to distribute power demands among the generators. They

also monitor the instruments that regulate the ow o electricity

rom the plant. When power needs change, they start or stop the

generators and connect or disconnect them rom the circuits. Many

operators use computers to keep records o switching operations

to track the loads on generators and lines, and to prepare reports o

unusual incidents, malunctions, or repairs that occur during thei

shit.

Power Distributors and Dispatchers operate equipment tha

controls the ow o electricity rom a power plant through

transmission lines to substations that supply customers needs. Theyoperate converters, transormers, and circuit breakers. Dispatchers

monitor the equipment and record readings at a pilot boarda map

o the transmission grid system. It shows the status o circuits and

connections with substations and industrial plants.

Dispatchers also anticipate power needs, such as those caused by

changes in the weather. They call control room operators to start or

stop boilers and generators. They also handle emergencies such as

line ailures and route electricity around the afected areas. In addition

dispatchers operate and monitor the equipment in substations. They

step up or step down voltage and operate switchboard levers, which

control the ow o power in and out o the substations.

Civil Engineers make site visits, prepare engineering studies, and

design or evaluate various types o hydroelectric dams, powerhouses

and other project structures. They develop graphs, charts, tables

and statistical curves relating to these studies or inclusion in

environmental impact statements and assessments and dam saety

reports. Civil engineers require a bachelors degree in engineering.

Environmental Engineers o proposed hydroelectric projects review

environmental reports and exhibits. A main component o the job

is to study aspects o environmental impact issues, determine the

scope o the problem, and propose recommendations to protect

the environment. They perorm studies to determine the potentia

impact o changes on the environment. Environmental engineers

require a bachelors degree in engineering.

Electrical Engineers design and develop electrical systems andequipment, evaluate electrical systems, and ensure stability and

reliability. Electrical engineers require a bachelors degree in

engineering.

Hydropower Engineers work with teams o environmental scientists

and engineers to review, analyze, and resolve engineering and

environmental issues associated with proposals to construct and

operate hydroelectric projects, including major dams, reservoirs, and

power plants. Hydropower engineers require a bachelors degree in

engineering.



Hydropower Resources and Career InformationBureau of Land ReclamationExplores the Hoover Dam. Learn how the dam was built, view

construction era photographs, and learn how the dam operates as

one o the largest hydroelectric power plants in the country. The

site includes educational resources or teachers.

www.usbr.gov/lc/hooverdam/index

Career Voyages

There are two interesting resources or all careers. Watch InDemand Occupation Videos at www.careervoyages.gov/

careervideos-main.cm. This website eatures short videos or

occupations ound in the Bureau o Labor Statistics Occupational

Outlook Handbook. This is an excellent place to see careers in

action. Click on InDemand Magazine to view or download

several magazines with an introduction to the diferent career

paths in construction, energy, advanced manuacturing, and

health care, and the young proessionals who have chosen those

careers.

www.careervoyages.gov

Federal Energy Regulatory CommissionVisit the Students Corner section to learn more about hydropower.

This website includes games and photos o dams and hydropower

plants.

www.ferc.gov/students/index

Foundation for Water and Energy EducationWatch a video o hydroelectric power production, take a virtual

tour o a hydroelectric plant and a generator, and learn how a

hydroelectric project can afect a river.

www.fwee.org

Hydro Research FoundationLearn about hydropower as a renewable energy resource and take

a Hydro Venture, an excellent resource that explores all aspects o

hydropower using real lie photos.

www.hydrofoundation.org

Idaho National LaboratoryHas extensive inormation about hydropower and new

technologies.http://hydropower.id.doe.gov/

National Hydropower AssociationsCovers basic inormation (see Fact Sheets under Hydro Facts)

about hydropower in all o its orms, both conventional and

new technologies as well as hydropower issues as they relate to

legislative and regulatory issues. The website also includes many

links to other hydropower resources and is a great place to start

or everything that is hydro.

www.hydro.org

PBS: Building BigThere is a section on dams. Ater learning about the diferent

types o dams, take the dam challenge. As a consulting damengineer, you decide whether to repair, take down, or leave alone

several diferent dams.

www.pbs.org/wgbh/buildingbig/dam/index.html

U.S. Department of EnergyEnergy Information AdministrationUp-to-date data and inormation on all energy sources, including

hydropower.

www.eia.doe.gov

Dams Contribute to Other Employment

When Hoover Dam (near Boulder City, Nevada) was built on theColorado River, it created

energy of moving water

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