Freeze Greenland's Meltwater

[Enthalpy]

Hello responsible citizens, perspicacious scientists, and megalomaniac engineers!

 

A research team has found much liquid meltwater 5-50m below ice surface between the ice particles in Greenland's ice sheet:

http://www.bbc.co.uk/news/science-environment-25463647

http://www.nature.com/ngeo/journal/vaop/ncurrent/full/ngeo2043.html

Observed over 70,000km², this reservoir could represent 140*10¹²kg/yr meltwater, or 0.4mm/yr sea level rise, half the contribution of Greenland, provided it does flow into the Ocean now or later, which is still unclear.

 

Human technology may prevent this contribution to sea level rise. Collect this water, bring it to the surface when the air is cold, leave it there to freeze. This goal is at grasp: the Dutch achieved a similar one when they reclaimed land from the sea, without our present technology.

How to collect the water in 1,200 wells over the area isn't clear to me - ask a specialist.

How much power does it need? Only mean 870MW to bring the water amount from -20m to the atmosphere. If wind is reasonably favourable there (to be checked), then 1,200 land wind turbines of present 3MW technology suffice, spread over the reservoir area equivalent to Ireland. Or find a different energy source; the temperature difference between this water and the atmosphere is a big power difficult to exploit.

How expensive? A park of peak 1,800MW - half the power, but offshore makes it twice as expensive - was bought for 2.5G€.

http://de.wikipedia.org/wiki/Siemens_SWT-6.0

 

At this price, we avoid 2cm sea level rise in 50 years.

Marc Schaefer, aka Enthalpy

[EdEarl]

Such a big project would, almost certainly, cause unintended consequences; although, I cannot fathom what they might be. Perhaps the cavity created from pumping may collapse, which might not be bad. But, if geothermal energy is keeping the water melted, it would probably melt collapsed ice. Your idea seems worth discussing and modeling.

[Enthalpy]

All engineering projects bring some unexpected results, hi colleague; it is more the size of the consequences that increase with the size of the undertaking...

 

This liquid water just impregnates snow that is partially compacted ("FIRN"), so removing it shouldn't let the snow collapse.

 

To my understanding, there are further 3,000m ice below the water reservoir, which must stop at the depth where snow is compacted to ice. So geothermy - which would have ruined the attempt - is not the cause of liquid water there. The authors suppose that fresh snow at the end of Summer insulate this water from cold air.

[Trumptor]

Is preventing sea level rise of 2 cm in 50 years worth 2.5 Gazillion Euros?

[Enthalpy]

G is the prefix to Giga, that is 10⁹.

[Trumptor]

Oh, thanks:) Well still, is it worth 2.5 GigaEuros?

[Enthalpy]

Collecting the water that impregnates firn may not be so difficult.

A machine inspired from these that dig trenches for cables is much cheaper than the park of wind turbines. It shall dig trenches down to the compact ice. Advancing in snow at 50mm/s only during daytime of summertime, it digs 300km per year. That's about the size of the meltwater reservoir.


Then you can cover the trench with snow to prevent water from freezing there. Water is to seep from the snow walls and run on the ice bottom, possibly in a man-made half-pipe there. Maybe a permeable cover protects the half-pipe from collapsing snow. The trench can be renewed regularly if necessary.

An additional possibility is to let the trench open to cold air, so that seeping water freezes in the trench and makes it impermeable. Combined with the slope of the hard ice below, this would accumulate water where it shall be pumped.

It isn't easy to move wind turbines, but fastening them in ice is easier than in soil. If they can be moved from time to time, then water needs to be collected just locally.

At favourable locations, pumping may not be necessary. An impermeable full pipe might accept water accumulated by the impermeable trenches and carry it by gravity to the surface of lower locations where it shall freeze.

Marc Schaefer, aka Enthalpy