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Energy 101: Geothermal Energy


See how we can generate clean, renewable energy from hot water sources deep beneath the Earth's surface. The video highlights the basic principles at work in geothermal energy production, and illustrates three different ways the Earth's heat can be converted into electricity.

Text Version

Below is the text version for the Energy 101: Geothermal Energy video.

The words "Energy 101: Geothermal Energy" appear onscreen, followed by footage of a natural hot springs swimming pool.

You may have relaxed in a natural hot springs pool.

Footage of a hot water geyser.

Or seen the Old Faithful geyser blasting hot water into the air in Yellowstone National Park. But have you ever thought of where all that heat comes from?

Footage of natural geothermal features.

Well, it comes from deep beneath the surface of the earth—and it's called geothermal energy.

Footage of various geothermal energy facilities.

And we can use it to generate clean renewable electricity.

OK, here's how geothermal works.

Animation of how geothermal energy is generated underground.

Heat from the earth's crust warms water that has seeped into underground reservoirs.

When water becomes hot enough it can break through the earth's surface as steam or hot water. This usually happens where the earth's crust or "plates" meet and shift.

Footage of various geothermal energy facilities.

In the past, taking advantage of geothermal energy was limited to areas where hot water flowed near the surface. But as geothermal technologies advance, we can leverage even more of these natural renewable energy sources.

Engineers have developed a few different ways to produce power from geothermal wells drilled into the ground.

Footage of a dry steam geothermal energy facility.

Have a look at this. It's a dry steam geothermal power plant, and it's the most common type of geothermal technology used today. Underground steam flows directly to a turbine to drive a generator that produces electricity. Pretty straightforward.

Animation of how geothermal energy is generated through a flash steam power plant.

Another geothermal technology is called a flash steam power plant. A pump pushes hot fluid into a tank at the surface, where it cools. As it cools, the fluid quickly turns into vapor—or "flash" vaporizes. The vapor then drives a turbine and powers a generator.

Footage of a binary cycle geothermal energy facility.

A binary cycle plant works differently.

Animation of how geothermal energy is generated through a binary cycle power plant.

It uses two types of fluid. Hot fluid from underground heats a second fluid, called a heat transfer fluid, in a giant heat exchanger. The second fluid has a much lower boiling point than the first fluid, and so it "flashes" into vapor at a lower temperature. When the second fluid flashes, it spins a turbine that drives a generator.

Footage of various geothermal energy facilities.

The environmental benefits of this clean, round-the-clock renewable energy source are substantial: low emissions, small physical footprint, and minimal environmental impact. The few byproducts that can come up are often re-injected underground.

Footage of a geothermal facility that recycles its wastewater.

Geothermal energy can also help recycle wastewater. In California, wastewater from the city of Santa Rosa is injected into the ground to generate more geothermal energy.

Footage of a geothermal facility that recovers and recycles its sulphur byproduct.

Some plants do produce solid waste, but that solid waste may contain minerals that we can remove and sell, which lowers the cost of this energy source.

Footage of various geothermal energy facilities.

The U.S. Geological Survey estimates that untapped geothermal resources in the United States, if developed, could supply the equivalent of 10% of today's energy needs.

In fact, electricity generated by geothermal energy already provides about 60% of the power along the northern California coast.

Footage of the Golden Gate Bridge and a coastline.

From the Golden Gate Bridge to the Oregon state line.

Footage of various geothermal energy facilities.

Geothermal energy…helping to push America toward energy independence, and a clean, renewable way to meet our growing energy demands.

Caption: Energy 101: Geothermal Energy. For more information, visit