[ExI] Glacier Geoengineering
nebathenemi at yahoo.co.uk
Sat Feb 13 20:34:13 UTC 2010
Keith put numbers on pumping ocean water on to the East Antarctic plateau as follows:
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
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
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.)
First, a quick double-check - wikipedia reckons ~3.61 x 10E14 square meters of earth's surface is ocean, so pretty close to Keith's figure. I just plugged 3.61E14 / (60x60x24x365) to get 11,447,235 cubic meters per second, so within about 5% of Keith's figure. So, even with pumps converting 90% of energy going in to potential energy of the water, we're looking in the 350-400GW/yr range to do one meter/year.
But, do we really need to pump a whole meter in year? 1993 to 2003 had an average sea level rise of 3.1mm/year. The IPCC estimates
come out at from 1.1m to 6.4m higher in 2090-99 compared to 1980-99. So, say we start planning now and are ready to start the pumping in ten years - 2020. Then we need to do 1.1m to 6.4m over 80 years. Let's say 4m as a middling figure - then instead of 400GW for 4 years, we can do 20GW over 80 years.
Sure, the power plants will need rebuilding more than once. I'm assuming we're going with nuclear to avoid shipping large quantities of fuel to the antarctic, and to keep it soot-free and low carbon (don't want to accelerate that antarctic coastal glacier breakup!). UK nuclear plants built since the 1970s have expected operating lives of 30-40 years
If we're being optimistic and following Sizewell B, you're getting 1.1Gw for 40 years, but a couple of reactors on that table are "running at 70% indefinitely" so instead of 18 of these needing replacing once, we'll probably need 25 replacing once or twice. This will cost many tens of billions, but should keep pace with ocean sea level rise and avoid the risk of losing places like London, New York, most of the Netherlands (worth a lot in terms of real estate) and the human misery of trying to resettle tens of millions from Bangladesh and low-lieing areas around the Indian Ocean.
Tom (enjoying geoengineering chat as a change from philosophical musings)
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