Geothermal mapping report confirms vast coast-to-coast clean energy source

[Viking]

The problem with low temperature and low pressure geothermal (which is what this article identifies as a source of energy) is that it can only be used for heating houses. Once the need for local domestic heating has been reached geothermal is uninteresting. Not all kilowatts are equal. For producing electricity you need pressure and you need pressure substantially higher than then pressure from the water column. Since the article doesn't mention pressure I am tempted to merely dismiss it. The examples of operating low temp geothermal are to the best of my knowledge heating.

You need high pressure and temperature to produce electricity with geothermal. Low temp geothermal does not do that. The usefulness of Geothermal is local heating. What I do expect is to see local geothermal wells where surface water is injected into a lined well that then uses the geothermal gradient to warm it so that it can be used in a hot water radiator. Low temp geothermal cannot be used for electricity generation.

I suspect this article has been filtered through a few journalists and not enough engineers and geologists. The facts may be true but nobody seems to have told the journalist that the X billion gigawats being discusses are of very limited usefulness.

[Richard Hakluyt]

Geothermal energy is energy from radioactivity. So I win anyway.

My understanding is that radioactive decay contributes in only a minor way to the continued hotness of the inner Earth, and most is simply leftover heat generated during the Earth's formation.  Incorrect?

My understanding is that it's the other way around. But quick googling paints a picture of significant uncertainties in this question, with numbers all over the place.

This recent shit claims it's 50/50: http://physicsworld.com/cws/article/news/46592

I also thought that it was much more, perhaps 80-90%. Another opinion on the matter :

http://www.physorg.com/news62952904.html

[Viking]

BTW, the SMU map is temperature at 6500 meters. That is really really really really deep. Only the largest rigs can drill that deep.

[grumbler]

The problem with low temperature and low pressure geothermal (which is what this article identifies as a source of energy) is that it can only be used for heating houses. Once the need for local domestic heating has been reached geothermal is uninteresting. Not all kilowatts are equal. For producing electricity you need pressure and you need pressure substantially higher than then pressure from the water column. Since the article doesn't mention pressure I am tempted to merely dismiss it. The examples of operating low temp geothermal are to the best of my knowledge heating.

You need high pressure and temperature to produce electricity with geothermal. Low temp geothermal does not do that. The usefulness of Geothermal is local heating. What I do expect is to see local geothermal wells where surface water is injected into a lined well that then uses the geothermal gradient to warm it so that it can be used in a hot water radiator. Low temp geothermal cannot be used for electricity generation.

I suspect this article has been filtered through a few journalists and not enough engineers and geologists. The facts may be true but nobody seems to have told the journalist that the X billion gigawats being discusses are of very limited usefulness.

Well, the engineers who looked at this would note that your assumptions about how geothermal heat is used is mistaken.  The hot water is used (in modern geothermal plants) to heat an organic liquid like n-Butanol* (which has a much lower boiling point than water), which is then used to drive the turbines, and then is re-condensed and run through the geothermal-heated water again. 

http://www.ormat.com/solutions/Geothermal_Binary_Plant

It can be combined with a geothermal water cycle to create a combined cycle generation system.

Iceland, I believe, still uses steam generators, because it has high-pressure/high temperature steam available, but plants in the US and elsewhere are being built for combined cycle use of much cooler and lower-pressure steam.

* I am not sure that n-Butanol was the compound that finally won out in geothermal production - I am using it here as the placeholder for whichever of several similar molecules finally won out as the production working fluid.

[grumbler]

BTW, the SMU map is temperature at 6500 meters. That is really really really really deep. Only the largest rigs can drill that deep.

Quick check says that's three times the depth of the average oil and gas well in the US in 2008.

[Neil]

Geothermal energy is energy from radioactivity. So I win anyway.

And friction.

[grumbler]

And friction.

science friction?

[Neil]

And friction.

science friction?

Isn't all friction science?