E-Book Overview
When a puddle dries up, where does all the water go? The science matters series provides a compelling introduction to key science topics, explaining concepts in a format that encourages reading and comprehension. Each title introduces a core science topic through visual diagrams, hands-on experiments, and fascinating biographies, all engagingly written.
E-Book Content
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 engine