FREEZING THE PERMAFROST

How does man survive in temperatures above his natural body temperature? By evaporating his perspiration. Heat, called latent heat, is needed to change a liquid into vapor, and this heat is extracted from the adjacent medium, lowering its temperature, or at least keeping it constant in spite of the higher ambient temperatures.

On the contrary, when a vapor condenses, this latent heat is returned, keeping the liquid warm. That is why people's breath only fogs an ice-cold car window, but does not immediately freeze on the glass.

In summer, when the air is warmer than the ground, the cycle is interrupted automatically, for no heat transfer can take place in the opposite direction. But the refrigeration in winter is not only sufficient to keep the ground frozen through the summer; it also increases the adfreeze bond by a factor of 3, which allows a reduction of about 40 ft in the length of the piles required to support the projected load.

The embedded end of the cryo-anchors is flexible, allowing long lengths to be coiled or folded for shipping. The system is cheap (compared with other alternatives), requires no power or controls, and a minimum of maintenance.

There is a widespread belief that environmental opposition made the oil companies think up this kind of safeguard, and that the 4 years' delay was well worth while to preserve the Alaskan wilderness.

This is patent nonsense. The narrow strip of the pipeline would hardly have affected the hundreds of thousands of square miles of Alaskan tundra. But the real reason for the cryo-anchors is that without keeping the soil frozen, the pipeline, whether imbedded or on supports, would be subject to vertical movements of some 18 ins. per thaw or frost, and the resulting shears would ruin both the pipeline and the oil companies' budgets. As for the environmentalists, they did not want a safe pipe line, they wanted no pipeline at all.