Water Power (Science Matters)

Studying Water Power Electricity makes machines run. Coal, gas, and oil are often used to create electricity. These sources, called fossil fuels, will eventually run out. There is a limited supply of fossil fuels because they are found only in some 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 power comes from hydroelectricity. • The state of Washington creates more hydroelectric power 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 expensive method of creating electricity in the United States.

On the Move Water is constantly moving. Currents and tides help move water around the world. Currents are the paths along which bodies of water move. Tides are the regular rise and fall of water level in the ocean. The movement of water is very powerful. It creates energy. Water power changes 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. Large waterfalls, such as Niagara Falls, create electricity in this way. Falling water is directed into long pipes connected to a power station. The force of the moving water 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. Ocean currents 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 be used to create electricity. Water boiled under pressure creates steam that is full of energy. Inventors created steam engines using this energy. Steam engines powered factories, 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 energy because the flow of water is part of the water cycle. Water recycles itself through the water cycle. This diagram shows how the water cycle works. /•••

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Hydroelectric Dams Dams are built to stop flooding, to provide water, and to create electricity. Dams are built of concrete that is reinforced with steel. Most dams are built in a curved shape. This provides a much stronger structure against the water currents. As water collects behind a dam, the energy level in the water builds. When the water is released, the flowing water gains speed. The flowing water passes through turbines 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 more power can be produced. Water can be directed back into the reservoir to be reused. Reservoirs also supply drinking water. People can fish in reservoirs. They can even be used for water sports such 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?

Advantages • Hydropower is cheaper to create than power from fossil fuels. • Water power does not cause pollution. • 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 to create electricity. Tidal power stations can only create power when the tide is flowing in or out. This happens for about 10 hours per day. Only about twenty sites in the 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. Gold had been discovered in California, and many people had 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 power machinery and mills. Waterwheels did not work well in nriountain creeks; ¡ ¡ ! While watching a waterwheel, LeSter Peltori saw a bar called a shaft slip. He saw that the wheel spun faster when water hit the edge of the wheel than when it hit the center. Lester Peiton created a new, more efficient design 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? Encarta Homepage www.encarta.com • Type any water power-related term into the search engine. Some terms to try include "hydroelectricity" and "dam." How can I find out more about water power and hydroelectricity? Water Science for Schools http://ga.water.usgs.gov/edu •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 of the ball • a foam ball • plastic spoons • a large cup • water • a sink or large bowl 1. 2. 3. 4. 5. 6.

Poke the skewer through the center of the ball. Wiggle the skewer until the ball easily spins around it. Place the plastic spoons evenly in a row around the ball. Make sure the scoops all face up. Fill the cup with water. Hold the ball by the skewer over the sink or bowl. 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? Name two ways in which water moves. What causes a waterwheel to move?

What is another name for water power?

What stores water behind a dam?

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

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Which country is the number one producer of water power? What machines create electricity from water energy?

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Earth of water?

Wor artificial: something made by people, not nature

millwright: a person who sets up machinery in a mill

boiler: a large tank that heats water and turns it into steam

pollution: harmful materials such as gases, chemicals, and waste that dirty air, water, and soil

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

recycles: returns to an original condition so a process can begin again renewable: can be made like new again

Appleton, Wisconsin 5

Hoover Dam 14

steam 10,11

currents 6,8,14

Kuroyon Dam 16

dams 14,15,16,17, 18,20

lakes 12,16

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

Niagara Falls 7 energy 6,7,8,10,11, 12,14,17,18 environment 4,15,17

oceans 6,8,13 Pelton, Lester Allan 19

factories 8,9,10 fossil fuels 4,7,17

rivers 5,8,9,13,14,18

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