4 ms·

Maybe this is a dumb question but is pumping sewage effluent into it as the water source a great idea?

• pfdietz 2y ago
  Why not? The average reservoir steam temperature is well above boiling (370 F, 83 psi) so it's completely sterilized. In comparison, an autoclave used to sterilize surgical instruments (say) reaches 250 F.
  • 0cf8612b2e1e 2y ago
    Does not change your point, but an autoclave is also pressurized.
    • lazide 2y ago
      Ack, any temperatures above the boiling point of water at STP is going to require pressurization. Autoclaves are low pressure compared to this system.
  • lazide 2y ago
    One reason may be contaminants. Most sewage water has a lot of salts, proteins, weird minerals, heavy metals, etc. in it which can cause cause significant corrosion and other issues even at room temperature. However, most geothermal systems already have issues with lots of salts and minerals being pulled from the surrounding rock (even with in-Situ water), to the point that maintaining equipment when things are constantly trying to dissolve and/or crystallize in them is one of the dominant costs. So as long as the water is treated enough it doesn’t ‘cook’ into a gelatinous mass when it hits the hot rocks, it probably isn’t making the problem any worse.
    • pfdietz 2y ago
      If anything, I imagine the geothermal system could act to destroy otherwise hard to remove organics, like drug residues. Various dissolved metals and metal-rich surfaces could act as catalysts. Some geothermal systems in the Salton Sea have had issues with deposition of metal sulfides, with the deposits being so rich in silver they are in effect high grade ores (including native silver metal). Unfortunately these weren't economical to extract, but they do act as artificial replicas of natural ore forming systems.