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[KaguroDraven]

Geothermal power is amazing and nearly limitless. All you do is dig a deep pit, pour water into that pit, and then when the water turns into steam use the steam to run turbines.

Limitless energy anywhere on the planet. It runs day and night, generates no pollution at all, and only requires a source of water to run. You can recycle most of the water as well. Once it runs through the turbine let the steam condense and cool back into water, then pump the water underground again.

I'm still unsure why geothermal is not used more often.

Technicly the water is recycled automaticly, as it turns into steam, clean hot water in gas form.

[Scaraban]

Geothermal power is amazing and nearly limitless. All you do is dig a deep pit, pour water into that pit, and then when the water turns into steam use the steam to run turbines.

Limitless energy anywhere on the planet. It runs day and night, generates no pollution at all, and only requires a source of water to run. You can recycle most of the water as well. Once it runs through the turbine let the steam condense and cool back into water, then pump the water underground again.

I'm still unsure why geothermal is not used more often.

because its a pain in the ass almost everywhere except iceland

[Hyndis]

Technicly the water is recycled automaticly, as it turns into steam, clean hot water in gas form.

Yes, but if you don't pump it back underground it just floats away as steam, which then turns into rain elsewhere. Nuclear reactors churn out massive amounts of steam, but this is why nuclear reactors are built next to rivers or lakes to provide the huge amounts of water. If water isn't as plentiful then the water would need to be recycled and pumped back underground.

Geothermal can be depleted through for each site, but its just an issue of you have X amount of thermal energy at the site. If you are trying to produce more than X amount of power its going to start to go cold. To increase X you need to dig deeper. The deeper you go the more heat there is, and so the higher the maximum production of the borehole.

[Vehudur]

This is why we should build magma rigs on active volcanoes, so that the magma comes to us instead of us digging down to the magma and burning to death in the consequent eruption because we needed to haul that sock that fell in the volcano or something.

too bad volcanoes erupt and spew sulphur, and ash everywhere. if not chunks of rock. bad idea to have a building on top of that hmm?

I just had the mental image of a building rocketing into the sky because of the pressure

No, it would be rocketing into the sky in a million pieces.

Volcanoes build up enough pressure to literally blow the tops off mountains.  Nothing we could possibly build could contain that.  We don't even know exactly how much pressure is actually there - we can't build anything that will last long enough to measure it.

Brain food inside:

Spoiler (click to show/hide)

When a volcano erupts, it will do one of two things, depending on the type of volcano.  There are various hybrids of these, and if you throw water in, well...  things get interesting.

You have to know a few basic things to understand these first:

* Magma has a lot of dissolved gasses.  The more pressure you put on it, the more it can hold.  As it rises, the pressure drops, and that gas is released.  Funny enough, this gas is mostly water and CO2.  Magma, however, is generally so thick that it cannot boil out, and will build up pressure.  Like a bomb.  Almost exactly like a bomb.  Thinner magmas make weaker bombs, however, because more gas can escape.  The magma cooling underground will diffuse this "bomb" via (really complex) chemical reactions and gas seepage.

1.  If it is an effusive eruption (thin magma, basalts - See: Hawaii) the lava will ooze out of the ground, bubbling.  If it's a lot, or under a lot of pressure, you may get a lava fountain.  In rare cases, a lava fountain may be a mile tall.  It then flows downhill, as a wall of fiery death - however, in most cases (not always), it's so thick that it moves no faster than 2 or 3 mph at the front of the flow.  You can outpace it with a typical walking speed.


2. If it's an explosive eruption (thick magma, so rhyolite - See: Krakatoa) then the lava gets a few unusual properties:
As the gas contained comes out of solution and forms bubbles, the bubbles then actually make the liquid thicker.  This makes it move up the vent slower, but there's still all that pressure behind it.
Eventually it reaches a point where it gets so thick that it stops flowing.  It then either will form a plug (and not erupt, but what fun is that?) or it will promptly detonate - it behaves like a solid and fractures, and this releases all some of that trapped gas.  Sort of.
Before it explodes, it might be 20% gas by volume.  40% if it's really really frothy.  After it explodes, it's 80%+ gas.
This bomb eruption cloud continues up the vent, at speeds that can be up to several hundred miles per hour, until it leaves the vent.  At that point, the gas expands the rest of the way.  It can, in a large eruption, breach the sound barrier while leaving the crater.
This evacuation of mass rapidly travels upwards - or, as was demonstrated with Mt. St. Helens, will travel whichever direction is most convenient to it. (Are you going to tell it no?)
This mixture of gas, lava and rock (the lava hasn't cooled yet, the rock is usually already solid rock torn from the vent on the way up), is much denser than air.  It's also very hot, and a gas.  And traveling upwards, very quickly.

The second one means it pulls in air from the surrounding atmosphere and entrains it in the ash column. 
It will either pull in so much air that it becomes less dense than the surrounding air and keeps rising, until it reaches a point of equilibrium where it is the same density of the surrounding atmosphere, at which point it will stop rising keep rising through sheer inertia (overshooting top, like a thunderstorm), fall back down, and then settle at the point of equilibrium.  This means that whoever is downwind gets a nice volcanic shower.  Be warned:  some of those chunks can be rather large and still hot if you're close enough.  Most of the time, it's just a mess.

Or, it won't.
It won't pull in enough air (or, more commonly, only part of it will pull in enough air), and fall back down.  Did I mention that it's in a gas state, even with big chunks of lava in it?  It then flows along the ground like a twisted demonic avalanche so hot you get to watch your skin burn off for a few seconds before your eyes boil, if it doesn't just flat out kill you from the sheer impact of it (you just got hit by a wall of flying, superheated gas and rock)
This is Real Fun.

That last part is the most fun.  I don't think I missed anything important. 

Also, geothermal power is pure awesomeness, but it's so hard to get down as far as you need in most places.  Or, you can move to Iceland.

[decius]

Technicly the water is recycled automaticly, as it turns into steam, clean hot water in gas form.

Yes, but if you don't pump it back underground it just floats away as steam, which then turns into rain elsewhere. Nuclear reactors churn out massive amounts of steam, but this is why nuclear reactors are built next to rivers or lakes to provide the huge amounts of water. If water isn't as plentiful then the water would need to be recycled and pumped back underground.

Geothermal can be depleted through for each site, but its just an issue of you have X amount of thermal energy at the site. If you are trying to produce more than X amount of power its going to start to go cold. To increase X you need to dig deeper. The deeper you go the more heat there is, and so the higher the maximum production of the borehole.

More properly, nuclear reactors use rivers to condense the steam and recycle the same water for the turbines. River water has lots of dissolved minerals that steam turbines don't like, and reactor water has Fun products of fast neutron bombadment that organic molecules, like DNA, don't like. Some systems have 3 loops, 2 closed, one open, for reactor water:turbine water:river/ocean water. Closed lakes are a poor choice for cooling water, since the end result is heating up the entire lake.

[Hyndis]

Yes, you're going to be using a closed loop regardless of what kind of power plant it is. But you still need to be able to cool the liquid in the closed loop, and that liquid does not always need to be water. Molten sodium is sometimes used in some nuclear power plants. The easiest way to condense a hot substance is to run it through water. This transfers the heat to the water, and if the substance is very hot the cooling water will turn into steam.

If you can build your power plant next to a natural source of water, like a river or a very large lake you're fine. If there is less water in the area then you're going to need to conserve the water and recycle it rather than let it float off into the air as steam.

[Vehudur]

Nuclear reactors are wonderful, except when they're built poorly, like a certain Ukrainian reactor...

[Drawde]

I'm still unsure why geothermal is not used more often.

As mentioned above it's quite hard to reach in most places.  Not to mention that you have to be reasonably close to the heat to prevent the water from cooling by the time it reaches your turbines.  So if you have to dig down 7+ miles to reach a suitable site you have to BUILD the power plant there.

Plus many of the gasses released by the geothermal site itself are rather corrosive.  Any machinery you build has to be able to resist that or it falls apart pretty quickly.  Which is quite expensive.

[Urist Imiknorris]

<recycled water>

<need to contain the water>

<stuff>

Then build it in the rain forest.

[Scaraban]

<recycled water>

<need to contain the water>

<stuff>

Then build it in the rain forest.

brilliant all our problems are solved!!! hallelujah uristimiknorris has saved us all!!! 

[NightmareBros]

I still think building on top of the volcano is a good Dwarfy idea if you build one of those stacks you often see at steel works on it.
And then did some other stuff like add lava flood release controls, put pipes suicidly close to the magma to get near-instant condensation and thus geothermal power, make supports for the stack so that rocks and earthquakes won't make it fall over and dump magma everywhere like a badly built BoatMurdered, but lots and lots of buidlings in a perimeter around the volcano, channel a moat for the lava to collect and stop melting people and buildings, Build a noble's bedroom in the middle of the stack that just so happens to dissatatch at the push of a button...

[Akura]

The problem with building on a volcano is that a volcanic eruption is generally preceded by earthquakes, typically severe ones.

Also(and don't quote my poor geology knowledge on this), the volcano is usually only active for a short time(the eruption), which is the only time a thermal reactor would be useful. The reason that geothermal power is effective in Iceland is because it's located right on top of a tectonic split, where the crust plates are seperating, creating a nice little canyon right into the molten layer. It might also be feasable in Hawaii, which is located on top of(and is being formed from) a hotspot.

[Eagle_eye]

or we could always just put a giant mirror in space and use the heat from that to drill down to the magma! oh... wait.....

[Hyndis]

You can get heat anywhere, its just easier to do it where the crust is thinner. That means less digging needs to be done. In the case of Hawaii you don't need to dig at all, lava just sort of spews out all over the place on its own.

[Lord Darkstar]

Geothermal power is amazing and nearly limitless. All you do is dig a deep pit, pour water into that pit, and then when the water turns into steam use the steam to run turbines.

Limitless energy anywhere on the planet. It runs day and night, generates no pollution at all, and only requires a source of water to run. You can recycle most of the water as well. Once it runs through the turbine let the steam condense and cool back into water, then pump the water underground again.

I'm still unsure why geothermal is not used more often.

Earthquakes.

When you pump extra water down into the rock like that, you get a lot of quakes. Do that near a major fault, and the worry is that it will trigger a MAJOR eruption, as the water is reducing the friction between the plates, which is what is preventing another quake.

Federal goverment won't even allow companies in the US to do this near major faults or cities or "Other important areas or structures" now.

What is allowed is to drill a few hundred feet down, and run a tube down and back. Cold water pumped through that tube will return very warm in most places of the US. Better than solar heated water.