Do you know what it is like at the center of the earth?
It is very, very hot.
The temperature is thought to be about 13,000 °F (7000 °C), which is hot enough to melt rock.
The heat spreads to the rock around the center of the earth and to water trapped between the layers of rock.
In some parts of the world, this hot water is close to the earth’s surface.
By pumping it out of the ground as hot water or steam, engineers have tapped a new source of energy. This energy is called geothermal energy, which means it is heat energy from under the ground.
Tropical fruit grows in Iceland!
Hot water from inside the earth may be used directly to heat buildings.
In Iceland, where there are many hot springs, hot water heats greenhouses and swimming pools as well as homes. And although Iceland is close to the Arctic Ocean, people living there can grow bananas and other tropical fruit in their greenhouses!
Steam condenses into white clouds of water vapor rising from these hot springs in Iceland. Several countries have developed geothermal power plants to heat homes and generate electricity.
In one kind of geothermal power station, cold water is pumped down a pipe into the earth and is heated by hot rock. Another pipe brings the hot water to the surface.
Several countries in the world, including the United States, Italy, and New Zealand, have built geothermal power stations. Steam, coming out of the ground at high pressure, is used to run steam turbines that generate electricity.
Engineers are trying to find out how more countries might use geothermal energy.
They started with a question. If the rock below the surface is hot but there is no water down there, why not drill a hole through the rock, pump cold water down and let the rock heat it up?
Then the water could be pumped up again through a second hole.
Some engineers are working on an even better idea.
They want to build a geothermal power station underground, which would generate electricity.
Then only an electric cable would be needed to bring the electrical energy to the surface of the earth.