In Yellowstone National Park in Wyoming, one of the most popular tourist attractions is a geyser known as Old Faithful." The neat thing about Old Faithful is that it spurts hot steaming water out of the ground at pretty predictable intervals – predictable enough that you can probably time your trip to Yellowstone to see Old Faithful erupt several times a day. If you don't happen to live nearby, you can always use the miracle of technology and check out the Old Faithful webcam.
Video: Old Faithful Geyser Eruption (1:28)
PRESENTER: Old faithful here in Yellowstone National Park in July, getting ready for the eruption here.
Old Faithful here.
When you watch Old Faithful erupt, what you are seeing is geothermal energy in action. If we could just place a nice shiny turbine on top of the geyser's cone, whenever Old Faithful erupts (about every hour and a half or so), the force of the steam would spin the turbine, generating a nice flood of low-carbon electricity.
No one seriously talks about generating power from Old Faithful, but the heat beneath the surface of the earth could provide a gigantic store of energy – if only we could get at it at some reasonable cost. There are a few places, like California, Alaska, and Iceland, where geothermal energy is used to generate a lot of electricity (in Iceland's case, basically enough for the whole country). There are a lot more places where engineers are hoping that we could generate even more electricity from geothermal energy, using techniques collectively known as "enhanced geothermal."
In this section, we'll talk about how geothermal energy works and where it is currently used. We'll also talk about the potential, and some possible pitfalls, from enhanced geothermal. One really intriguing idea that we won't talk about in this section is using heat in the very shallow surface (maybe as little as fifteen feet below ground) to heat and cool your home. This idea, called "ground-source heat pumps" or "ground source heat exchange" is growing in popularity for new home construction and has the potential to save a lot of energy in buildings. But we'll wait for that until we talk about energy conservation. Here we'll stick to producing electricity directly from the heat deep within the earth's surface.