[ExI] extropy-chat Digest, Vol 77, Issue 12

[Keith Henson]

On Sun, Feb 7, 2010 at 5:00 AM, Tom Nowell <nebathenemi at yahoo.co.uk> wrote:

> Keith's proposal relies on using a lot of organic liquids with a low vapor point.
>
> Keith, how are you proposing to trap the vapor, condense it and re-use it? If this process isn't highly efficient, you get two big problems:

Heat pipes are sealed, passive devices.  It's hard to put a number on
their efficiency besides 100%.  http://en.wikipedia.org/wiki/Heat_pipe

> 1) you need to add a lot more liquid, which costs energy to make, adding to expense and cost
> 2) you have to worry about the environmental problems when the vapor condenses somewhere else. In fact, even with a tiny amount of leakage this can become a problem. I'm not sure how much of these it would take to become toxic rather than mild irritants, but in the volumes needed to freeze glaciers there is a risk of a major spill. Seeing as places with the huge glaciers like Antarctica and Greenland have coastlines with fragile polar ecosystems, I can see this being a problem.

Propane and ammonia (two good choices) don't cause environmental
problems in the small amounts used.

> In Kim Stanley Robinson's recent trilogy of ecothrillers (40 days of rain/ 50 degrees below/ 60 days) one of the protagonists investigates geoengineering for a presidential candidate and advises him in the last book. The scheme they use for direct lowering of sea-levels is pumping sea water on to the West Antarctic where the glaciers are highly stable, and increasing glacier coverage that way.

I think you mean East Antartic but I am not sure this would be a good
idea.  The salt in seawater might cause the glaciers to soften and
slide off into the ocean.  Of course, if you are going to pump water
upwards more than a few hundred meters, it only cost 200-300 meters of
head to take the salt out with osmosis.

Interesting concept though.  To put numbers on it, the area of the
earth is ~5.1 x 10E14 square meters.  3/4 of that is water, so ~3.8
10E15 square meters.  To lower the oceans by a meter in a year would
require pumping
at 1.21 x 10E7 cubic meters per second.

12,100,000 cubic meters per second.  Hmm  The flow of the Amazon is
219,000 cubic meters per second, so it would take 55 times the flow of
the Amazon.

Pumping it up some 3000 meters to the ice sheet would take
considerable energy, P=Q*g*h*1/pump efficiency (0.9).

1.21*10E7*9.8*3000/0.9 = 396 GW.  400 one GW reactors would do the
job.  (Please check this number.)

Keith

> Tom