3 ms·

>Not if you keep pumping in water to run a steam turbine. Are you being serious? In terms of known capabilities the Kola borehole shows that even with older te

by xoa 10y ago

>Not if you keep pumping in water to run a steam turbine. Are you being serious? In terms of known capabilities the Kola borehole shows that even with older tech we can drill down to over 12km in depth, and there have been decades [1,2,3] of efforts drill all the way through the Mohorovičić discontinuity into the mantle (20+km minimum from a continental starting point, 5-10+km from ocean). Lithosphere/mantle boundary tends to be defined by temperature, in that around 1800°F is when the weakest common mineral (olivine) begins to exhibit viscosity. Well before that it'd reach the point where the amount of pressurized water we could pump through it wouldn't be able to keep up with new thermal load. So yeah, at some depth the rock is always extremely hot. In terms of economics though of course there is some set of balance points for a given level of tech and economics between cost of drilling to a given depth, gains in lifetime/power density, maintenance costs, costs/losses of actually moving working fluid from heat point to generator, reliability advantages, etc etc. Presumably experts go through and consider all of this, it should be tractable within some set of risk bars. If an experienced power company is actually putting down millions on doing a project after evaluation, I see no reason to doubt that they've done the math to their/their investors' satisfaction to a level sufficient for a pilot project. 1. http://www.smithsonianmag.com/science-nature/decades-long-quest-drill-earths-mantle-may-soon-hit-pay-dirt-180957908/ http://www.smithsonianmag.com/science-nature/decades-long-qu... 2. https://en.wikipedia.org/wiki/Chiky%C5%AB https://en.wikipedia.org/wiki/Chiky%C5%AB 3. https://www.extremetech.com/extreme/247370-drill-baby-drill-japanese-scientists-hope-reach-earths-mantle-massive-drilling-project https://www.extremetech.com/extreme/247370-drill-baby-drill-...

BurningFrog 10y ago
I'm just making the simple point that however hot the rock is, it will cool down when you pour enough water on it. I don't know what the Mohorovičić discontinuity is, but I'm sure it doesn't change this physics fact.
- mmmpop 10y ago
  The rock will radiate heat sufficient enough to boil the water before it can even come close to coming in contact, so no, basic thermodynamics would like a word with your physics fact....
  - askvictor 10y ago
    And the water, in boiling, will remove some of that heat that would otherwise radiate back. The entire premise of geothermal energy is removing some heat from deep down in the earth. Whether that amount is big enough to cause a noticeable difference is was is being debated.

by xoa 10y ago

BurningFrog 10y ago

I'm just making the simple point that however hot the rock is, it will cool down when you pour enough water on it. I don't know what the Mohorovičić discontinuity is, but I'm sure it doesn't change this physics fact.

mmmpop 10y ago
The rock will radiate heat sufficient enough to boil the water before it can even come close to coming in contact, so no, basic thermodynamics would like a word with your physics fact....
- askvictor 10y ago
  And the water, in boiling, will remove some of that heat that would otherwise radiate back. The entire premise of geothermal energy is removing some heat from deep down in the earth. Whether that amount is big enough to cause a noticeable difference is was is being debated.