science matters water power

• Water power is the most efficient and least expensivemethod of creating electricity in the United States... The energy created by water falling from a high level to a low level can be

Studying Water

Power

Electricity makes machines run Coal, gas, and oil areoften used to create electricity These sources, calledfossil fuels, will eventually run out There is a limitedsupply of fossil fuels because they are found only insome areas Fossil fuels can also harm the environment

Water can be used to create electricity Water power is

renewable and environmentally friendly Water power

is called hydroelectricity

• Americans use electricity to cook, light their homes,

and power appliances, including the washer and dryer.

Water Power Facts

Water creates about 20 percent of the world's

electricity There are many more interesting

facts about water power.

• Canada is the world's largest producer of

hydroelectricity.The United States ranks second

• About 10 percent of the United States's electric powercomes from hydroelectricity

• The state of Washington creates more hydroelectricpower than any other American state About 87

percent of Washington's electricity is produced

by hydroelectric facilities

• The world's first hydroelectric power plant opened

on September 30,1882 It was located on the Fox

River near Appleton, Wisconsin

• Water power is the most efficient and least expensivemethod of creating electricity in the United States

On the Move

Water is constantly moving Currents and tides helpmove water around the world Currents are the pathsalong which bodies of water move Tides are the regularrise and fall of water level in the ocean The movement

of water is very powerful It creates energy Water powerchanges this energy into electricity

In most places, the tide rises and falls twice each day.

Water for Electricity

Burning fossil fuels releases harmful gases into the air Fossil fuels are expensive and will not

last forever.

The energy created by water falling from a high level

to a low level can be used to create electricity Largewaterfalls, such as Niagara Falls, create electricity inthis way Falling water is directed into long pipes

connected to a power station The force of the movingwater nnakes waterwheels in the power station spin.The spinning waterwheels cause machines called

turbines to turn.These turbines create electricity

Water Power

in History

People have used water's energy for thousands of

years Ancient Greeks and Romans used waterwheels

to grind wheat into flour and to grind corn Oceancurrents have brought many explorers to their

destinations River currents have pulled heavy

logs to sawmills Water power is still used to saw

wood and power mills and factories

• Many early millers relied on river currents to bring logs

to their sawmills.

The Waterwheel

The waterwheel was the first machine created to

use water power Waterwheels often powered mills and factories.

Waterwheels need moving water, so they are built on rivers and streams Flowing water strikes the wheel's blades in the water.The water pushes the blades,

causing the wheel to turn.The spinning waterwheel powers machines.

Power from a waterwheel is not always reliable During

winter, water often freezes Sometimes a drought leaves

people with no power.

Steam Power

Over time, people discovered that steam could also beused to create electricity Water boiled under pressurecreates steam that is full of energy Inventors createdsteam engines using this energy Steam engines poweredfactories, farm machinery, locomotive trains, and ships.Steam engines are still used today to create electricity

• In 1801, Richard Trevithick built the first locomotive.

It traveled at 5 miles (8 kilometers) per hour.

How a Steam Engine Works

A steam engine needs a boiler.The boiler boils water

to produce steam under pressure This creates energy.

The steam in the boiler expands and pushes against a piston or turbine A turbine is a machine that changes the steam's energy into electricity, i i

Steam engines are not the best way to create

electricity Of the energy used to heat the water to

produce steam, only 35 percent becomes electricity.

H James Watt built the first steam engine.

Hefinished the design in 1778 i i

The Water Cycle

Water power is a renewable type of energybecause the flow of water is part of the

water cycle Water recycles itself through

the water cycle This diagram shows howthe water cycle works

/ • • •

Hydroelectric Dams

Dams are built to stop flooding, to provide water, and

to create electricity Dams are built of concrete that isreinforced with steel Most dams are built in a curvedshape This provides a much stronger structure againstthe water currents

As water collects behind a dam, the energy level in thewater builds When the water is released, the flowingwater gains speed The flowing water passes throughturbines that change the water's energy into electricity

• The Hoover Dam blocks the Colorado River.The dam creates electricity.

Environmental Issues

Water power is clean It does not release harmful gases into the air Still, using dams to create electricity affects the environment.

When a dam is built, the land around the dam is usually destroyed.To save the environment, plants and trees need

to be replanted Rocks need to be replaced Construction

on dams can also cause flooding.The environment may never return to normal ,, ,i i, i ,, , ;

Storing Power

Reservoirs store water for creating electricity They are

found behind dams A reservoir is like an artificial

lake The deeper the water in the reservoir, the morepower can be produced Water can be directed backinto the reservoir to be reused

Reservoirs also supply drinking water People can fish

in reservoirs They can even be used for water sportssuch as kayaking

• The Kuroyon Dam in Kurobe, Japanjs one of the world's largest dams It is 610 feet (186 meters) high and 1,614 feet (492 m) long.

Good or Bad?

The chart below lists some of the advantages and disadvantages of water power Can you think of other points to add? Do you think using water to create electricity is a good idea or a bad idea? Why?

• The electric energy

created by water power

can be used immediately.

Disadvantages

• Dams are expensive

to build.

• Building dams destroys

the environment and can

cause flooding.

• Turbines can hurt animals

in the water.

Tidal Power

The energy in tides can be used to create electricity.Tidal power is created using a huge dam built across

a river estuary The tidal waters flow through tunnels

in the dam The water then passes through turbines tocreate electricity Tidal power stations can only createpower when the tide is flowing in or out This happensfor about 10 hours per day Only about twenty sites inthe world can be used to create energy from tides

• Tidal water builds up in estuaries When water is released from the estuary, the turbines move, creating electricity.

A Life of Science

Lester Allan Pelton

Lester Allan Pelton lived in Caiifornia in 1849 Goldhad been discovered in California, and many peoplehad moved there Pelton worked as a carpenter and

millwright.The gold mining industry was growing

fast, so there was great demand for new ways to powermachinery and mills Waterwheels did not work well innriountain creeks; ¡ ¡ !

While watching a waterwheel, LeSter Peltori saw a barcalled a shaft slip He saw that the wheel spun fasterwhen water hit the edge of the wheel than when it hitthe center Lester Peiton created a new, more efficientdesign for a water turbine after seeing thisJ

Surfing Water

Science

How can I find more information

about water power?

• Libraries have many interesting

books about water power.

• Science centers and museums

are great places to learn about

water power.

• The Internet offers some great Web

sites dedicated to water power.

Where can I find a good reference Web

site to learn more about water power?

•This United States Geological Survey Web site offers

pictures, data, and maps It even has an interactive center where you can test your water knowledge.

Science in Action

Build a Waterwheel

You can build your own waterwheel to see the power of water

in action.

You will need:

• a long skewer or stick

about twice the length

• a sink or large bowl

1 Poke the skewer through the center of the ball.

2 Wiggle the skewer until the ball easily spins around it.

3 Place the plastic spoons evenly in a row around the ball.

Make sure the scoops all face up.

4 Fill the cup with water.

5 Hold the ball by the skewer over the sink or bowl.

6 Raise the cup of water as high as you can Pour the water

over your waterwheel.

What happens? Try pouring the water from higher and lower levels Does the level change how the waterwheel spins?

hat Have You Learned?

a dam?

What is the most efficientway to create electricity'n the United States?

í Which countryis the number

one producer

of water power?

What machinescreate electricityfrom water energy?

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Earth

of water?

artificial: something made by

people, not nature

boiler: a large tank that heats water

and turns it into steam

dams: walls built across streams

or rivers to hold back and

control water

drought: a long period with no rain

estuary: the mouth of a river where

the river meets the sea and is

affected by the tides

millwright: a person who sets up

machinery in a mill

pollution: harmful materials such

as gases, chemicals, and waste that dirty air, water, and soil

recycles: returns to an original

condition so a process can begin again

renewable: can be made like

steam 10,11

tides 6,18 turbines 7,11,14,17, 18,19

Washington 5 water cycle 12-13 waterwheel 7,8,9, 19,21