Jamie_L

Exactly. This is what I was getting at.

The Core seems to take a factual idea (Spinning core = magnetic field. No magnetic field is bad.) and creates some total B.S. science so they can fit in all the action sequences that their formulaic plot-generator has devised.

Jamie

Shadowy Man

Yes, in the long term. If the Earth were to suddenly lose its magnetic field we'd probably have at least thousands (if not millions) of years to think about what to do.

[edited to add: Sorry. It's just these kind of movies tick me off... taking such license - and people will believe it, too.]

[ December 24, 2002: Message edited by: Shadowy Man ]</p>

Mageth

Yeah, but the new "walking compass" I got for Xmas would no longer work!

thebeave

I just had a thought. During periods of magnetic field decline and reversal, it would seem that life on this plant would be exposed to higher levels of ionizing radiation from space. Since ionizing radiation is known to cause mutations, would we see a more rapid pace of evolution during this time, and perhaps greater diversity of life? It seems like it would result in a huge increase in "environmental stress" on the average lifeform.

Shadowy Man

Well, it seems that proton levels would increase in the upper atmosphere, possibly producing more air showers of muons and stuff, but certainly radiation a la photons wouldn't really be affected.

Are there correlations between the fossil record and magnetic reversals?

ps418

That's an interesting empirical question. In many oceanic sediment cores, it is easy to compare evolutionary rates in planktonic organisms with magnetic intensity records. As far as I can recall, no one has demonstrated any correlation between mag intensity and evolutionary rates. Plus, there are long periods of geologic time characterized by few reversals and high field intensity (e.g. the Cretaceous Superchron), and these do not seem to be associated with slower rates of evolution, as far as anyone has noticed. If there is an effect yet to be found, it must be a small effect.

Ruy Lopez

Seeker196;
26 000:I hadn't realized how far down the necessary temperature to boil water was, I thought that even at 10 000 feet a small super-insulated tube would boil. I wouldn't consider drilling ten thousand feet an impossible notion.

Oh well, there's always GIANT ORBITAL MIRRORS...I can dream can't I...?

There are at least two things to remember whenever proposing viable technological projects that would serve the community on an on-going basis. First, the physical installation must be safe, legal, reliable and last for 30 years. Second, everything one does costs money and has to be paid for with profit on top.

Geothermal exploitation requires three things to happen. First, a source of heat at depths no more than 16,000 feet; only crustal fissures/fractures can heat rocks at this depth. Second, an aquifer of ancient meteoric water at the SAME place. Third, a geologic trap to prevent the superheated pressurized water/steam from escaping to the surface. Without one of these three; no geothermal power plant.

As would be deduced from the above, exploitable geathermal phenomenon are site- specific and occur at very few places on earth. Oil deposits are more commonplace. Also geothermal energy IS NOT intensive or concentrated like oil or uranium. A single well reaching 6,000 to 14,000 feet down yields anywhere from 2MW to 12MW. Thus to feed a teeny weeny geo power plant module of 55MW requires collecting steam from 5 to 12 wells.

I suggest you forget what you see in the movies and search the web instead; or at least do not assume movies are realistic. Topping the upper mantle means you have to drill 90,000 feet on flat land, 300,000 ft on mountainous terrain and 20,000 ft of hard basaltic rock under the ocean floor. Drop the idea or no one of consequence will take you seriously.

Also geothermal resources do not last 10,000 years; windpower does. Geothermal gets exhausted once the aquifer is depleted because reservoir recharge is bound to be slower than planned exploitation rates. To prolong reservoir/aquifer life, it is best to pump back the effluent into the reservoir. Don't spill effluent on land; streams, rivers and farmland would be contaminated and you would have farmers running after you with machetes.

beausoleil

Approximately 90% radioactive decay, 10% latent heat of crystallisation as the outer core solidifies onto the inner core.

Seeker196

90 000 feet, that is deep.

Obviously, if it couldn't be done anywhere and everywhere, then we are constrained by all the textbook factors you mentioned, (covered in UWOs 'GEO202E: structure of the earth' course), which I was discounting.

Few things I'm still having difficulty with:
Why the water obsession? Can't we just use a really good, insulated conductor to directly draw heat to drive a 'kettle' like apparatus?
Heat from, say, a magma chamber.

Don't be too hard on me, it's not like I'm seriously proposing this or anything, just blueskying after work.

Ruy Lopez

Quote: Don't be too hard on me, it's not like I'm seriously proposing this or anything, just blueskying after work. Quote:

Okay, I thought you were being serious.

Quote: Few things I'm still having difficulty with:
Why the water obsession? Can't we just use a really good, insulated conductor to directly draw heat to drive a 'kettle' like apparatus?
Heat from, say, a magma chamber. End Quote:

Cannot imagine what you mean by "kettle-like apparatus" and insulated conductor; thus cannot answer. "Water obsession"? Water is the medium that transmits the energy to the surface. Without the trapped water, one wouldn't know if he has a geothermal resource. I would not know what would happen if one were lucky to find a magma chamber and pumps cold water directly into it. The pros do not do that. I can see though that it would be a feeble uneconomic attempt.

Will be glad to reply to more .