Geothermal steam power generation takes a lot of water and water is in short supply.  Normally it is pumped down into the rock to create the steam, it comes up contaminated with whatever minerals are there, often dangerous metal sulphates.  The geysers of Yellowstone are full of minerals.

Geothermal heating/cooling with direct circulation and heat pumps could reduce heating/air conditioning energy use to such an extent that it could replace maybe 40% of present electric power use.

That's the equivalent of 400 nuclear power plants or 1000s of geothermal steam plants.  Geothermal heating/cooling is the conservation aspect of energy re-evolution, along with conservation from more efficient buildings, appliances, and plugin vehicles.

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Or schools, factories, restaurants,hotels, government buildings, and so forth?

I think they use heating/cooling electric power too.  Not to mention food processing, distillation, food storage, it can all benefit from conservation using geothermal heat pump heating/cooling.

31% is a pretty encouraging  conservation target on the home front.

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I think we're seeing some confusion of terms in this last comment. Just to be clear, the geothermal energy in DR's post refers to tapping energy from really hot rock, deep underground, usually to generate electricity as well as to supply district and process heating. It's a large-scale industrial-grade technology.

Ground source (and water source) heat pumps are a different animal altogether, using heat pump technology to leverage the fairly constant ambient temperature to be found in shallow drillings, trenches and ponds relative to the much wider seasonal and diurnal variations in the local air temperature, and they are most commonly used (at least in my neck of the woods) in small-scale installations for individual residential heating and cooling.

Both are really significant, important and valuable technologies and both are well worth developing as part of our long-term energy strategies.

The true meaning of life is to plant trees, under whose shade you do not expect to sit.

No confusion, geothermal steam turbine power uses too much water and contaminates ground water.  It is not practical in it's present form.

Geothermal heating/cooling using direct circulation and heat pumps is capable of saving a huge portion of our total generating capacity.  and substituting for combustion of fossil fuel for heating.

By using heat pumps to store heating/cooling capacity in buildings, food storage facilities, and other large heating/cooling uses, electric power can be stored when solar and wind produce excess power that exceeds demand.  A way to avoid backup generation and electrical storage.

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David Roberts wrote: Nuclear power sales in 2005: $64 billion
Geothermal power sales in 2005: $1.1 billion

Nuclear power has 98 gigawatts of capacity installed. Geothermal power has 2.8 gigawatts of capacity installed.

Ratios of billions of dollars in sales to gigawatts of capacity:

Nuclear: 64/98 = $.65 billion/gigawatt capacity.
Geothermal: 1.1/2.8 = $.39 billion/gigawatt capacity.

Nuclear power capacity is 67% more effective at producing revenue.

This is really off-topic but as several posters have brought it up: thermal mass in a building is an extremely useful concept for levelling out highs and lows when ambient temperatures oscillate above and below desired comfort temperature on a diurnal basis and of significantly less value when this does not apply. This is why thick-walled masonry structures are traditional in the deserts of the American southwest, for example, but not in the warm humid forests of the American southeast. Night-time cooling is of little value when the temperature does not fall below 80° and the RH below 98%.

In the Antarctic, I believe a steady-state heating condition applies pretty much all year, even in the summer. Thermal mass would seem to be of significant value only if you were to be so foolish as to not have an airlock on the doors, or to leave them open.... What really matters is the insulation, not the mass.

In fact in an unheated small building thermal mass can be a detriment: a thermally-lightweight small enclosure such as tent can actually be warmed pretty quickly by the body heat of its occupants. Don't expect this in a stone hut. This of course is why sleeping bags are made of down.

I should mention that thermal mass can also be valuable in turning an intermittent heat source such as a wood fire into a steady emitter more like a modern heating system. To maximize this benefit the mass should be concentrated close to the heater, as in a traditional Russian stove: mass in the shell of the building is of lesser value.

In this as in all our building practices it would behoove us as we go into a more frugal future to look at traditional ways of doing things which are local to our own area: how did people manage to live comfortably in this place in the past, before the the profligate use of cheap energy became the norm?

The true meaning of life is to plant trees, under whose shade you do not expect to sit.

Meant to place the above post in the small house thread, it's even more off-topic here. It's now in both locations, using up twice as many valuable electrons as it should. How unfrugal of me. Sorry!

The true meaning of life is to plant trees, under whose shade you do not expect to sit.

Said another way, doesn't this also mean that Geothermal costs 67% less per Kwh?

Thats actually a great arguement for geothermal versus nuclear.

They aren't monetizing the cost of of anything besides operations, maintence, and fuel.

Which would be like coal fired power plant not monetizing emmisions, or the payback of the facility.

Or better yet, Solar has 0 cents per year in O&M and fuel.  Beat that :P