4 ms·

Thermal conductivity is one of the parameters that varies by more orders of magnitude than most properties in everyday materials. Aerogels 0.024 W/m·K Aluminu

Thermal conductivity is one of the parameters that varies by more orders of magnitude than most properties in everyday materials. Aerogels 0.024 W/m·K Aluminum 240 W/m·K https://en.wikipedia.org/wiki/Caprock https://en.wikipedia.org/wiki/Caprock says that sandstone is a common type of rock there, and has a thermal conductivity of 2.4 W/m·K So I guess on a log scale it's half way between! So I guess imagine it's drawing heat from a source that is 100x smaller cross section and made of aluminum. Not that that is particularly helpful...

Gibbon1 6y ago
Conduction is sort of dismal. Materials tend to conduct either too well when you don't want them to. And too little when you want them to. If you want to move heat from point a to b usually you want to use a fluid. That why I tend to assume for geo thermal plants you want to drill into rock where there is a lot of hydrothermal action going on. Something absolutely weird is Japan has basically zero installed geothermal power.
- neltnerb 6y ago
  Yes, I agree, I was surprised they bothered to mention trying to seriously mine heat from hard rock, it seems like running fluid through a bore horizontally barely solves the conductivity issue since heat still has to get to the walls of the bore. I'm not sure if you are unaware but: "In 2007, Japan had 535.2 MW of installed electric generating capacity, about 5% of the world total." https://en.wikipedia.org/wiki/Geothermal_power_in_Japan https://en.wikipedia.org/wiki/Geothermal_power_in_Japan Which sure, is the total equivalent of like two nuclear cores so small by any absolute measure, but they seem to be trying?
  - Gibbon1 6y ago
    Consider Northern California has about 900MW of geothermal installed and the state isn't really known for geothermal activity. Japan which is known for that, what are they doing?
    - neltnerb 6y ago
      To give California some credit, it is slightly physically larger than Japan, has far more open space without people despite the bay area (my first thought was "would they really be willing to wreck the onsens and such that have been there for a thousand years?"), is on active tectonic plates, and has been pretty focused on this for a while.
    - fomine3 6y ago
      Against by local onsen owner is a main blocker. It's hoped and some develop is ongoing, but we also like onsen.

Gibbon1 6y ago

Conduction is sort of dismal. Materials tend to conduct either too well when you don't want them to. And too little when you want them to. If you want to move heat from point a to b usually you want to use a fluid. That why I tend to assume for geo thermal plants you want to drill into rock where there is a lot of hydrothermal action going on. Something absolutely weird is Japan has basically zero installed geothermal power.

neltnerb 6y ago
Yes, I agree, I was surprised they bothered to mention trying to seriously mine heat from hard rock, it seems like running fluid through a bore horizontally barely solves the conductivity issue since heat still has to get to the walls of the bore. I'm not sure if you are unaware but: "In 2007, Japan had 535.2 MW of installed electric generating capacity, about 5% of the world total." https://en.wikipedia.org/wiki/Geothermal_power_in_Japan https://en.wikipedia.org/wiki/Geothermal_power_in_Japan Which sure, is the total equivalent of like two nuclear cores so small by any absolute measure, but they seem to be trying?
- Gibbon1 6y ago
  Consider Northern California has about 900MW of geothermal installed and the state isn't really known for geothermal activity. Japan which is known for that, what are they doing?
  - neltnerb 6y ago
    To give California some credit, it is slightly physically larger than Japan, has far more open space without people despite the bay area (my first thought was "would they really be willing to wreck the onsens and such that have been there for a thousand years?"), is on active tectonic plates, and has been pretty focused on this for a while.
  - fomine3 6y ago
    Against by local onsen owner is a main blocker. It's hoped and some develop is ongoing, but we also like onsen.