Although maybe it could be a 4-1-9 scam aimed at the Green movement.

        John chumari said:

the generator recycles the same electricity to run itself, and hence uses no fuel

ROFL!

Didn’t think anyone would fall for the perpetual motion machine scam these days…

It’s “barytes”.

In this case, it’s not the key to a bright future career that a college grad should consider taking up, but it is a key. It’s the key to how deep drilling is made feasible.

The article overstates the difficulties of deep drilling. I’m pretty sure it also understates the number of boreholes that are over 10,000 feet. I believe there have been multiple boreholes drilled to 18,000 feet or deeper in search of gas. And, IIRC, there are a number of producing gas wells at 12 – 14,000 feet.

The reason it’s feasible to drill this deeply is that dense powdered baryte minerals, when mixed into the drilling mud, can match the mud density to the density of the rock being drilled. So gravity does the pressurization automatically. At any depth, the static pressure in the drilling mud is the same as the static pressure in the surrounding rock, just by virtue of the column of heavy mud above it.

Blowout preventers are there for when oil or gas is encountered. Oil and gas have much lower density than rock, and if the borehole starts filling with them, the pressure in the upper regions of the well can shoot up. But they play little or no role in drilling operations at most times; they are not used for maintaining different working pressure levels at different depths of the bore, and are not needed for that. Gravity does it.

        Soylent said:

but it’s actually cheaper in most cases to drill a couple of holes down to a few hundred meters, line them with pipe and connect them at the bottom(don’t ask me how they manage to do this step, but apparently it’s not too difficult).

Actually, when I think about it a little more, it’s not that important that the pipes be insulated from each other(it does help, because you “mine” heat from different volumes of earth if they are separated), so they probably just insert a pipe that is folded into a U-shape into a single borehole and make as many boreholes as they need.

        drbuzz0 said:

Raising water any distance is going to require a significant amount of energy.

That’s not an analogous situation. A conceptual model is a U-shaped tube full of water; any potential energy gained by water comming up one leg is lost by water going down the other. The energy it takes to pump water around is entirely in the form of friction which could be very significant if the bottom of the ‘U’ is in the form of porous rocks.

For geothermal heat-pumps you’re just interested in getting at the average yearly temperature, you could just as well choose to bury a long, meandering pipe in your yard at a few metres depth; but it’s actually cheaper in most cases to drill a couple of holes down to a few hundred meters, line them with pipe and connect them at the bottom(don’t ask me how they manage to do this step, but apparently it’s not too difficult). Another approach that is popular here in Sweden is the bottom of a nearby lake; 4 degrees C is not significantly worse than ~7 degrees C which is the yearly average here.

        metatron said:

Nice explanation, but I’m wondering why it takes so much energy to pump the water back up again?
Taking an object from x down to y and back up to x shouldn’t result in the loss of any potential energy

(- some losses from friction) back in South Africa I toured a gold mine, and the water they brought back up from the deep shaft cooling systems was HOT.

Raising water any distance is going to require a significant amount of energy. At my parents house, they have a private well that goes down only about 150 feet, if not less. The well pump needs a dedicated 220 volt 20 amp circuit.

In theory if you force the water down it should displace an equal amount of water that comes back up, but in an injection well system, it’s actually a lot more complicated than that. The water is actually forced through porous rock and drawn up another pipe.

For 60 C some place like most of the US, Northern Europe, Australia (places where there’s no significant shallow geothermal activity) you still have to force the water down a shaft of at least a half to three quarters of a statute mile then into the surrounding rock strata and back up another equally deep shaft.

Much of the energy from the pressurization is lost because you are still pulling water up against its weight on one side. At those kind of distances you get almost no help at all from convection. The flow of the system has to be pretty rapid or much of the heat will be lost to the surrounding rock on the way up and the water temperature will just equalize to that of the surrounding rock.

Here is a diagram of “Hot Deep Dry Rock” geothermal: http://www.tfcbooks.com/images/misc/geothermal-m.gif

The only difference if you only need 60 C for heating is it doesn’t need to be quite as deep, but it does still need to be pretty damn deep.

Incidentally: deep mines use tremendous amounts of power to pump out water and keep the tunnels dry. Just one of the pump stations in a South African mine can have four 2.4 megawatt pumps for a total power usage of 9.6 megawatts per pump station and some of the large mine complexes have multiple pump stations of that size.

        metatron said:

What prevents you from drilling a well right under your customers? Then distance is no issue.

Cost and the suitability of the local geology.