Wouldnt we have an unlimited amount of energy if we drilled down toward the earths core and “harvested” the heat?
How far down would we have to drill? How far have we drilled already? Is anyone looking into this?
Cant we tap active volcanoes (from a safe distance)? It would seem that the Big Island of Hawaiis energy needs could easily be met by tapping into the Kilauea volcano.
We’d have to drill down very far to get to a region of the Earth with enough heat for areas NOT near volcanic activity.
There are geothermal plants in use. They are used in areas with natural hot springs, and so forth. Using them near active volcanos is dangerous, because you can never really predict what the volcano will do. Sure, for ten years it goes at a nice, slow pace, but what if there’s a surge/eruption? Say bye bye to that plant that has hot magma pumped right into it.
Right. The average crust depth is about 20 km. The deepest drilling to date was a research borehole on Russia’s Kola Penninsula, to a depth of over 12 km. And this took over 24 years, from 1970 until 1994. Highly impractical for geothermal power.
How far down though do you have to drill before, say, water boils? I thought I remember reading that some of the deeper mines we have the temperatures are like in the mid to upper 100’s. And those can’t be all that deep if we are actively mining those areas. What was the temperature at the 12km depth?
-XT
Did a little digging (heh!) and came up with this:
Well, then at 10k the expected temp was boiling (212 F)…and the actual was 356 F if my math is right. Even with the pressure thats well above boiling…and its obviously a reach-able depth, at least by drill. And surprisingly there is appearently water there already…so seems it would be at least feasable to generate steam in some way down there…and maybe at shallower depths. At least in theory.
-XT
I’ll bet dollar to doughnuts that I’m the only guy in the boards have been involved in drilling geothermal wells. Despite over thirty yaers of trying, it’s still very, very experimental. I was briefly involved in the Soultz project in the North of France. It took nine years to get the first electricity generated, but they managed it. There are several problems involved and solutions have to be found for all of them. I’ll try and write more later.
This can be done on recently errupted volcanoes, such as Lanzarote which last blew in 1730. It left a mountain of rock that is still hot, a geological eyeblink later. The mountain is covered with tiny black stones. Just a few inches below the surface, they are too hot to hold in the hand. Drill a few feet into the rock, and the heat is immense.
There’s an experimental technique I’ve read about called “Hot Dry Rock Geothermal”. The theory is, you drill 2 holes down until the rock becomes hot. Then, you use explosives or some other method to open a channel between them. Cool water is injected down one hole, and hot water come up the other. Unlike traditional methods, this works places that don’t have a preexisting layer one hot water to tap. Warning : I am not an expert. 2 links I googled :
There’s an experimental version of this in Southampton(UK), near where I live (NB: we’re not near any active volcanoes). I think it provides hot water and heating for a number of businesses and hotels local to the plant, but was not the unlimited supply of free energy that had been originally hoped for.
That’s why I love this place.
Why do we need water at all?
Why can’t we use thermo electric generators?
The have no moving parts, make no noise and only produce electricity
Because the current state of the art TEGs aren’t very efficient and don’t scale up very well (there are cost issues with some of the materials and alloys needed to make them work). I don’t know if the issues are insurmountable or just a materials science issue, but today they just aren’t ready for prime time on the scales we are talking about to produce energy in a country the size of the US with our huge energy needs.
Conventional heat engines are more efficient, in the sense that they produce more usable energy for a given amount of heat input. In some sense this is less important for a geothermal plant than for a combustion engine, say; you’re not paying for “fuel” in the case of a geothermal plant, so you can tap off as much heat as you want. However, if you’re going to go to the phenomenal expense of drilling a very very deep hole, you’re probably going to want to make your money back as quickly as possible, so it’s not like efficiency can be entirely ignored.
Also, note that this thread was originally started in 2005. But maybe its revival will inspire Tapioca Dextrin to finally tell us about his experience with geothermal plant engineering.
300 C, which is the limit the drill can stand.-That’s what they told you..actually, the “National Enquirer” carried the REAL story-when a microphone was lowered into the hole..it picked up the screams of the damned souls in Hell!
You still need water (or some fluid).
All heat-powered generators need a source of heat and a “sink” of cold - you can’t just put your magical thermoelectric generator at the bottom of a long bore, surrounded by hot rock, and expect to generate any power. You need to get the heat to the top of the ground, where the ambient temperature will provide the differential to generate the electricity.
Water is by far the most convenient working fluid, although I suppose you could use liquid salt or Sodium or something else.
What’s really creepy about this post is that you are talking to a literal dead person. QED died some time ago, IIRC.
Which would put a terribly somber and literalistic spin on “zombie thread”.
I actually wrote my original post above using that phrase, but then thought better of it.
I concede that a cooling liquid will make a thermocouple more efficient, however the
Way I understand them to work, is by a differential in temperature between the two junctions
Couldn’t the junctions be spread far enough apart to create a differential in temperature
Then stacking the to achieve a usable power level?
We don’t have to drill to 300c