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Iceland Eyes Liquid Magma As Energy Source
An anonymous reader writes "Scientists in Iceland have been studying and utilizing the power of geothermal wells for years. In 2009 one such study hit a standstill when a group ran into magma halfway into their dig. The roadblock has become a blessing in disguise, as recent research has shown that the magma can act as a potent new source of geothermal energy powerful enough to heat 25,000 to 30,000 homes."
Iceland already produces energy by pumping water into the ground and on to very hot but still solid magma to produce steam energy. So the distinction matter since the reaction is very volatile if the 'rock' is still liquid.
All geothermal energy comes from lava, it's just a matter of how directly you tap the heat. Heat engines run more efficiently with a higher heat difference, but they have to be designed/constructed to -use- that higher heat. If you cool the lava it will solidify into rock, and your expensive lava to electric generator stops working till you drill down to lava again. A lava generator is cheaper to build but has a shorter life span.
magma
n pl -mas, -mata
1. (Physics / General Physics) a paste or suspension consisting of a finely divided solid dispersed in a liquid
2. (Earth Sciences / Geological Science) hot molten rock, usually formed in the earth's upper mantle, some of which finds its way into the crust and onto the earth's surface, where it solidifies to form igneous rock
Collins English Dictionary
A plastic or paste. And, of course, you knew that magma could have a range of viscosity from cumbly-looking rhyolite-forming magmas ( Vesuvius, Krakatoa, Mount St. Helens) to fountain-like basalt forming lavas (Hawaiian volcanoes).
Please, stop cooling magma. No more viscous magna means no more earth magnetic field, hence no more magnetic shield, ie no more life.
Please, don't dig for geothermic energy. Leave alone our earth kernel.
Now let's do some math.
Mass of the earth: 5.9*10^24 kg. Apart from a very thin shell on top, most of that is at a couple of thousand degrees kelvin.
Magma has a much higher specific heat, but let's be conservative and assume all of earth has the same specific heat as iron, or about 460 J/kg
Cooling the earth by a single degree will release about 2.75*10^27 joules
The total world energy consumption from all sources in 2008 was estimated at 4.75*10^20 joules.
At that rate, cooling the interior of the earth by a single degree would power the entire world for 5,789,473 years.
And that's assuming the earth doesn't continue to generate heat from radioactive decay, tidal forces, friction etc.
Unless they're drilling a hole >3000km deep to tap into the iron-nickel liquid core of the Earth where the Earth's magnetic field is generated, the effect will be irrelevant. And that's leaving aside the fact that it's technically impossible to drill to such depths (the deepest wells barely exceed 10km). Besides, at most you're slightly accelerating the natural process of water circulating in the crust and the normal process of the Earth cooling -- at one teeny-tiny spot compared to, say, the entire mid-oceanic ridge system, which is naturally pumping water through the crust in the vicinity of magma chambers all the time and has been for eons.
Your logic is flawed because you have not considered scale. Total heat flux is estimated at 42TW, and there are ~40GW of geothermal heating and electricity generation. Even if we scaled up geothermal heating by a hundred times or more it wouldn't matter much. All we're doing is drawing the heat out a little faster in small areas, which wouldn't effect the Earth on a broad scale for many millions of years, if there was any effect at all. The Earth is big, and heat flow is remarkably slow within it (rocks are good thermal insulators). It's difficult to perturb heat flow except very locally by artificial means. And generally speaking the areas tapped for geothermal power already have elevated heat flows anyway.
You should worry more about wind turbines affecting weather patterns. At least that might have a plausible basis.
It's a wonderful idea (and don't get me wrong, we use geothermal energy in NZ [it's around 5% of our power generation]) but the inherent danger of magma is that if you make one little error you're dealing with MAGMA!!!
it's the second most hostile energy source after nuclear energy, the only difference is the half life isn't thousands of years.
oh! and 7000 is little more than 2 kilometres, that's really, really, really close for magma (the other way to look at it is that it's a very, very, very think mantle on the Earth near Iceland). Most other estiamtes of the Earth's mantle are ~=50-60 Km's vs. 3% of the average thickness beneath Iceland.
Good luck to Iceland!
Regards Sinesurfer A Nerd is someone who lives for technology, A Geek is someone who lives for technology and loves it