The wind, the sun and Earth give us energy. This energy does not ever get used up. This is called renewable energy.

Solar Energy

Solar energy comes from the sun.

One type of solar energy uses technology. For example, solar cells or PV cells are panels that capture sunlight. They then generate electricity.

Other types of solar energy use natural sunlight for heat. One example is building a house that faces the sun. More sun means more heat.

Solar cells work well. But they cost a lot.

Solar power cannot be used as the only power source in a community. That is because the sunlight we get depends on where we live, the season and the time of the day.

Wind Energy

We get wind energy from wind turbines. These are towers with two or three blades at the top. The wind turns the blades. The blades turn a generator inside the tower. The generator creates electricity. Turbines do not release pollutants into the air.

Groups of wind turbines are known as wind farms. Wind farms can be found near farms, mountains, and even in the ocean.

If winds are steady, we get cheap electricity. But wind speed depends on where we live and the time of the day. So we cannot rely on it fully. Also, wind turbines are dangerous for bats and birds. They can crash into them.

Geothermal Energy

The center of the planet is very hot. Geothermal energy makes use of this heat.

We get underground geothermal heat in different ways. One way is heat pumps. Hot water from underground is used to heat buildings. These pumps can also heat sidewalks and even parking lots.

In Iceland, there are large amounts of underground water. Almost 90 percent of people in Iceland use geothermal as an energy source. They heat their homes and businesses.

Another way to use geothermal energy is with steam. In some areas of the world, there is underground steam that naturally rises to the surface. The steam can be piped to a power plant.

Biomass Energy

Biomass is material that comes from plants or animals. Plants create energy from the sun. It happens in a process called photosynthesis. This energy is stored in the plants even after they die.

Trees, branches, and recycled paper are sources of biomass. Other sources of biomass are manure and crops, such as corn, soy, and sugar.

We get energy from biomass by burning it. Biomass can also be made into biofuel. It can help power cars and trucks.

Biomass can be stored and used when it is needed. But we need a lot of land and pesticides to grow biomass.

Hydroelectric Energy

Hydroelectric energy is made by flowing water. Most hydroelectric power plants are on dams.

Dams block the river and create a human-made lake. Some water flows out of the dam through tunnels. This water turns turbines. This creates electricity.

Hydroelectric energy does not cost much. Also, the dam does not depend on the weather and time of day.

But the human-made lakes can hurt the land around it. It can drown entire ecosystems and towns.

Other Renewable Energy Sources

Scientists and engineers are working on other renewable energy sources. One way uses ocean tides to generate electricity. Another way creates fuel from algae.