Geothermal Power - What's the Difference?

Geothermal power has been around for a long time, 70 or 80 years. It's just taking naturally heated fluid from within the Earth's crust and passing it through some kind of thermal cycle. All geothermal plants in the US since basically the 60s operate on that same principle. They're all built over what are called hydrothermal reservoirs where you have a confluence of three really important things.