Wind turbines. Solar cells

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Science and industry researchers are constantly finding ways to pro-

vide electric power more easily and inexpensively. As a result, innovations in electric power have made the industry cleaner and more efficient throughout its history, and made electric service available to millions of homes.

Wind turbines

With our lives centered around electricity, modern scien- tists have found innovative ways to convert the kinetic energy from the wind into electric power.

A wind turbine typically consists of a large, three-bladed propeller, called a rotor, atop a tower that’s high enough that

nothing blocks it from the wind. The turbine has a drive train similar to a car’s engine that includes an electric generator. The electricity generated gets added to the electric grid, which powers hundreds of homes and busi- nesses in a geographic location. Wind farms are becoming increasingly common in large open spaces.

Solar cells

The sun provides a significant amount of energy in the forms of heat and light. Solar cell technology, called photovoltaic (PV) cells, converts that light into electricity. These PV cells contain semiconductor materials such as silicon. Electrons in the semiconductor move when the material ab- sorbs the light.

Solar cells are versatile in size and portability. Large solar panels with hundreds of cells can be built in a factory and then sold to stretch out across land or mount on a rooftop. These large panels are used to power homes and businesses and must be re- placed after about 30 years. Small

solar panels with only a few cells gather enough energy to power standalone devices, like calculators and outdoor lighting.

Despite being a clean, renewable energy source, sunlight alone isn’t sufficient for those who want to use electricity at night or on cloudy days. In most cases, solar panels are a supplemental power source for a building that’s already attached to the electric grid.