[phreeza]

Pasting a comment here I made on the previous article:

To me the most important fact to keep in mind about geothermal is that the energy flow across the crust is ~0.1W/m^2. Compare that to the sun which has >100W/m^2 even at high latitudes. Of course this does not mean geothermal is useless (in particular heat pumps, if you count those, are great), but it goes a long way to explaining why geothermal isn't seeing the same explosion as solar.

[griffzhowl]

> the energy flow across the crust is ~0.1W/m^2

It's a misleading comparison. This is only the average amount of heat that diffuses through an ordinary patch of surface, and has more or less nothing to do with how a geothermal plant works, since they don't harvest heat by covering a large area of surface with conducting material.

The surface heat flow is low because rock acts as an insulator. If you drill down to where it's hot and draw the heat up you obviously get orders of magnitude larger flows of energy to the surface.

[phreeza]

Are you suggesting to basically harvest the thermal energy in the rock in a non-renewable fashion? I don't think that is very promising, the heat capacity of rock is not that huge.

Back of the envelope calculation is drawing 1 GW from a cubic Kilometer of rock would lower the temperature by 1 degree C every 25 days. So I think you'd deplete a typical borehole quite quickly?

[xnx]

Doesn't that deep down rock reach equilibrium with the system and is then limited by the flow rate?

[echelon]

> Compare that to the sun which has >100W/m^2 even at high latitudes.

Some places are covered with snow and get under 8 hours of sun a day, but your point still stands.

You know it's pretty compelling when there are several concurrent multi-billion dollar projects to transmit solar power from Africa, by undersea cable, to mainland Europe.

[linhns]

Should the technologies mentioned in the article can be perfected for large scale use, we would see a boom in geothermal, even larger than that of solar, as intermittency is automatically resolved.

Iceland and Australia would become new powers imho.