We visited the Trans Alaska Pipeline, which was an interesting example of creative engineering and use of chemistry. The pipeline is 800 miles long, brings oil from Alaska’s North Slope to Valdez, AK and cost about $8 billion to build in just over 2 years. Building a pipeline both above and below ground in a polar climate needed special engineering. I will talk about those features below.
The above ground construction is built in a zig-zag fashion with flexible connectors between pipe sections to allow for expansion and contraction of the pipe due to temperature changes.
The zig-zag construction of the pipeline. Photo by Zeb Polly.
Similarity the pipe sits on sled on sled like structure that can move forwards, backwards and side to side.
Sled like structure that holds the pipeline allowing for movement
The side supports are drilled down into the permafrost. As the oil moves through the pipe and the whole apparatus warms up, the support poles can melt the permafrost, which would cause instability. To alleviate the heat problem, each pole has two “heat pipes” which contain liquid anhydrous ammonia, which vaporizes below ground, rises and condenses above-ground, removing ground heat whenever the ground temperature exceeds the temperature of the air. Heat is transferred through the walls of the heat pipes to aluminum radiators that you can see sticking out of the top of the poles.
The flexible connectors between the pipe segments
Notice the connections in the pipeline and the aluminum radiators sticking out of the top of the support poles
A close look at the aluminum radiators that help to cool the gasified anhydrous ammonia back into a liquid. Photo by Zeb Polly.
When I head up to Toolik in May, we will be driving up the Haul Road for about 9 hours. I gather I will see a lot more of the pipeline as we travel up this road.
This is the group of 2012 polarTREC teachers at the pipeline. Photo by Zeb Polly.
Question to Ponder- Answer
(Which polar region is land surrounded by water and which is water surrounded by land?)
Answer: The Arctic is an ocean surrounded by land while the Antarctic is land surrounded by ocean.
Compare the two polar regions (photo courtesy of Polar Discovery, Woods Hole Oceanographic Institute).