![The deepest hole we ever dug was 500 degrees at the bottom, could a more shallow hole that could boil water be used to power a steam engine? [GIF - 18KB]](https://pic8.co/sh/azB0pa.gif){kind=link}
Assuming you could get the steam back up with it remaining steam, then yes. You'd need a lot of it, however, steam turbines consume quite a bit of steam during operation. They're actually under a pretty decent vacuum so the steam stays steam longer and you can extract more work from it.
The rest (condensing and stuff) is just regular power plant/steam turbine operation.
You wouldn't need to get the steam back up, would you? Just have it do it's thing at the bottom and turn a generator. Cables running up the hole would carry electricity. Then, ideally, you could get an almost reflux still effect in the hole, with the water. but getting additional water down would be easy.
The steam itself doesn't directly drive a turbine. It's just what causes enough of a pressure differential to act on the turbine blades and make the whole thing move. If you put everything down at the bottom of the hole, then the temperature and pressure would be equal across the system, and nothing would happen.
So instead you pipe the steam up from the source (where the temperature and thus pressure is high) into the turbines (where the pressure is low).
If you put everything down at the bottom of the hole, then the temperature and pressure would be equal across the system, and nothing would happen.
That can't be entirely true. If I had a sealed reservoir full of water, with a pipe going down into the water, and I throw it on the stove(or inside an oven for that matter), it will boil and water will come out of the pipe.
A piece of pipe full of steam at 500F is one thing. Putting a generator and all the associated equipment at that level would be problematic, and servicing would be impossible.
Countries with high volcanic activity already do this, so it's just a matter of finding an area where you can pipe the water around. In the USA, the Yellowstone region would probably be perfect for this.
Plus wouldn't boiling water like that below sea level at a higher atmosphere up the boiling temp?
Still would need a cooler, lower pressure place to exhaust the steam. The volume of water required would be large to get significant power from a turbine. People have done a lot of work in the field of "geothermal energy" and there's a fair amount written about it.
People have done a lot of work in the field of "geothermal energy" and there's a fair amount written about it.
If I wanted to actually put in the effort for this, would I be armchair engineering here?
Why do you have to exhaust the steam? Isn't piping that back into the cold instream a more efficient option?
That's not how it usually works.
What they do is, they run a pipe down the well deep enough that it will heat the water to near boiling then the pipe does a "U-turn" back up still liquid, but very hot. 99°C
Because the level is the same at the input (cold tank) as the output (hot tank), almost no energy is required for pumping. The water just levels out by itself.
Then a minuscule amount of natural gas is needed to finish boiling the water to turn it into steam to power the generator.
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