[ExI] Glacier Geoengineering

[Alfio Puglisi]

On Sun, Jan 31, 2010 at 10:52 AM, Keith Henson <hkeithhenson at gmail.com>wrote:

> The object is to freeze a glacier to bedrock.
>
> The average heat flow over the entire Earth is 87 mW · m-2
>

> http://www.answers.com/topic/earth-heat-flow-in
>
> http://geophysics.ou.edu/geomechanics/notes/heatflow/global_heat_flow.htm
>
> Call it 100-mW/square meter, tenth of a watt.
>
> A square km would have a heat flux of 100,000 watts or 100 kW
>
> Propane absorbs 428 kJ/kg evaporating.  It boils at one atmosphere at
> -43 deg C.  (Propylene boils about 10 deg colder so might use that
> instead.)
>
> http://www.engineeringtoolbox.com/fluids-evaporation-latent-heat-d_147.html
>
> So to pull 100 kW (a hundred kJ in a second) would take about 1/4 kg
> of propane per second.  That's 15 kg/minute.  Propane has half the
> density of water, so it would be in the range of 30 l/minute going
> down the hole.  Coming back up as vapor, a cubic meter has a mass of
> about 1.9 kg/cubic meter, so 15 kg/minute would be ~eight cubic meters
> per minute, or half a cubic meter per second.
>

Temperatures at the glacier-bedrock interface can be amazingly high. This
article talks about bedrock *welding* with temperatures higher than 1,000
Celsius:

http://jgs.lyellcollection.org/cgi/content/abstract/163/3/417

I guess the energy comes from the potential energy of the ice sliding down
the terrain.


This is only enough to take  out the heat coming out of the earth.  Probably
> need it somewhat
> larger to pull the huge masses of ice in a few decades down to a
> temperature where they would flow much slower.
>

If one also needs to remove the heat generated gravitationally, this could
be potentially much larger than just the Earth's heat flux.




>
> Glaciers cover about the same percentage of the earth as farmland.  I
> don't know how much of them would have to be blocked to slow them
> down, perhaps 5-10 percent of the area.
>
> Keith
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