Lexile 580; RAZ M; DRA 24
We need energy! We use it to run machines, to make food, and to turn on lights. Luckily, there is energy all around us. Earth's air and water are in constant motion. This motion can be turned into energy we can use. All we have to do is capture it.
Waterwheels are machines that use the power of moving water. Windmills capture the energy of moving air. For centuries, people have used waterwheels and windmills in many different ways. Today, most people use them to make electricity. How do these machines work?
This windmill pumps
water from the
ground up to a tank.
Energy in Motion
A waterwheel changes moving energy into a different kind of energy that can help us do things.
Water flows down a river and has a lot of moving energy. This energy pushes the blades of a waterwheel, making the wheel turn. When the wheel turns, it can move other parts of a machine.
Water can also provide power to cut logs.
The simplest waterwheel lies flat on its side. This is called a horizontal wheel. Part of it goes into a stream of water. The water makes the wheel turn.
Most waterwheels stand up tall. These are called vertical wheels. When the wheel turns, it makes a part inside called an axle turn too. The axle helps turn a big gear. The big gear then turns a smaller gear, and the smaller gear goes faster. This helps change the movement of water into energy. This energy can be used to do work.
Ye Old Waterwheel
Types of Waterwheels
One machine that uses water is a mill. A mill grinds grains, beans, or other hard things. In a sawmill, a waterwheel turns sharp blades to cut logs into wood. Some places that make ice cream, cheese, or butter still use waterwheels to help them.
Blowing in the Wind
There are many types of waterwheels. Two common ones are the overshot wheel and the breastshot wheel.
Today, some dams use turbines that work like waterwheels. These dams change water energy into electricity.
A long time ago, people used windmills to help them. Windmills could pump water from the ground or grind wheat into flour. The blades of the windmill were tilted to catch the wind. When the wind blew, the blades turned, just like a pinwheel toy. As the blades turned, they made a part inside the windmill spin. This spinning helped to move other parts, too.
Today, most windmills are used to make electricity. These new windmills are called wind turbines. Their long blades spin in the wind. The moving turbines create energy, which helps make electricity for our homes.
pinwheel toy
How Generators Work
Wind turbines are very tall. They have big blades that spin. When the blades are high in the air, they can catch more wind.
Some wind turbines are vertical. One type is called the eggbeater because its blades are shaped like an eggbeater. These blades are good at catching the wind. In vertical turbines, the control room is close to the ground. This makes it easier to fix them.
Other wind turbines are horizontal. Their blades look like airplane propellers. These turbines have a control room high up in the air. If something breaks, a worker has to climb to the top to fix it.
Turbines can make electricity. But how do they do that? They use generators!
Generators change movement into electricity. A simple generator needs energy, like moving wind or water. It has magnets and a loop of wire attached to a rod.
When the wind or water moves the turbine, it turns the gears. The gears make the wire loop spin. The loop spins between the magnets. When the wire loop moves fast by the magnets, electricity flows!
Modern Wind Turbines
Wind and flowing water can help spin machines called turbines. We can also heat water to make steam that spins turbines. We can use nuclear power and burn fossil fuels like coal to create heat and make steam.
Wind and water power are good because they are renewable. This means we can use them over and over. When we get electricity from water and wind, we don't burn fossil fuels. These kinds of power do not make bad gases or chemicals. This helps keep our air clean!
Energy for the Future