Construction Law

Alaska Permafrost Affected by Climate Changes Forces Innovation

By John P. Ahlers

Permafrost, the frozen ground that lies beneath the surface in most of the state of Alaska, has been melting due to higher than average air temperatures. The thawing of the permafrost and refreezing during the winter months causes foundation instability affecting the structural integrity of buildings, railroads, highways, and pipelines that sit on top of the frozen ground. When structures are built on frozen ground and the structural design depends on the ground remaining frozen. Engineers are turning to low tech solutions such as thermosiphons that draw heat out of the ground. It is a cost effective simple and innovative response to climate change.

The Thermosiphon, a tube filled with gas that cannot escape, is buried in the ground with the top exposed to the air. As the temperature plunges in winter the gas condenses into a liquid and falls to the bottom of the tube. When the weather warms up during the summer months, the warmth of the ground causes the liquid to evaporate back into a gas that rises to the top of the tube where the heat it carries is dissipated into the air the cycle keeps repeating itself, with no need for any kind of power source or any intervention other than maintenance. Scientists believe the process cools the ground around the tube so much during the winter that it stays frozen even in summer. Alaska Pipleline crews inspect the working of the thermosiphons using infrared cameras. If the telltale glow of heat being released is too dark, that indicates a gas blockage that may need repair. It appears Alaska has found a cost effective, low tech solution to climate change.

Carlton, Jim, "Keeping it Frozen" The Wall Street Journal, 12/07/2009

http://online.wsj.com/article/SB10001424052748704576204574531373037560240.html

Full post as published by Construction Law Blog on December 07, 2009 (boomark / email).