Im sure if put to scale, 7,000 feet wouldnt even be as deep as a dimple on a golf ball...a tad bit short of the Earths core.7,000 feet underground, where rocks radiate heat from the earths molten core
Look at it this way:And dont forget, according to our favorite scientist (and inventor of the INTERNET) the temperature of the earths core is "millions of degrees. (thousands, millions - whats three orders of magnitude when the issue is saving the earth?).
- If the earths core is hot enough to be molten Iron and other metals, it is way hotter than the surface.
- If the core is always hotter than the surface, heat is always flowing from the core to the surface.
- Anywhere on, or under, the surface of the earth where there is nothing to conduct heat from the earths core, will "radiate heat from the earths molten core.
And 7000 feet of earths crust is sufficient insulation to make the temperature at the earths surface (normal to us surface dwellers) distinctly cooler than the temperature over a mile closer to "the earths molten core.
https://www.youtube.com/watch?v=kGV7Dr2iDvU
He states that 2 kilometers down, the Earth is millions of degrees. Give that scholar a Nobel Prize.
As an aside, he starts out smugly stating that geothermal energy is relatively new. Again, he is wrong - its been used at large scale facilities since the 1920's.