Sipa via AP Images
DCL
If you remember anything about earth science, you know that at its center, the earth is hot. Magma hot. That's where geothermal energy comes from, and it's an important part of the renewable energy grid. It is the fourth largest source of renewable energy in the U.S. and currently supplies about 3,000 MW to the national grid
Only about five countries source more than 15 percent of their electricity from geothermal, but the number of countries that use geothermal grows to more than 70 when you include direct use
And here's a fun fact: the Idaho Capitol Building in Boise also uses direct geothermal energy for heating. You can even install a geothermal system to heat your home.
It's not a new concept: geothermal water was used by the Romans for treating eye and skin diseases and to heat buildings at Pompeii, and competition for control over energy sources is not new either: Medieval wars were fought for control over lands with hot springs. But while hot springs, as easily visible indicators, are often the first places geothermal energy is harnessed, the potential for geothermal as an energy source is actually much more widespread.
Heat flowing out from the earth's center in turn heats water, which can become trapped in permeable rocks under a second layer of impermeable rock, forming a geothermal reservoir. To generate electricity from geothermal heat, wells are drilled into these reservoirs to bring the water to the earth's surface, where the heat energy is then converted into electricity at a geothermal power plant. Learn how some of these geothermal power plants can work, or check out this video of geothermal energy in action.
Geothermal isn't totally greenhouse gas-free--carbon dioxide is released by geothermal power plants as a natural by-product of the fluids drawn from the earth, but the emissions are just a fraction of what fossil fuel plants release, and can even (potentially) be re-injected back into the earth. Geothermal power plants also demand a fraction of the land and freshwater of what nuclear or coal power plants require: geothermal uses 1 to 8 acres of land per megawatt, while nuclear uses 5 to 10 and coal uses 19. And geothermal uses 20 liters of freshwater per megawatt, whereas nuclear, coal, and oil all use more than 1000 liters for the same output.
Be sure to catch the COOLFUEL episode where Shaun and the crew rely on geothermal power and water power to get themselves across the American west without gas.
