Early in January 2008 Gov. Sarah Palin of Alaska approved an application from TransCanada Alaska Co., LLC/Foothills Pipeline, Ltd to build a gas pipeline from Prudhoe Bay, Alaska to near Edmonton, Alberta, Canada. It remains to be seen whether the line, as envisioned, will be built.
The project faces several technical challenges, including the requirement that the gas must be chilled to prevent thawing the numerous underlying ice lenses in the permafrost soils. Chilling the gas, while resolving a likely subsidence problem, creates another. A chilled-gas pipeline creates an artificial heat sink that can freeze any water flowing under it. In dangerous, discontinuous permafrost soils where water can freely move, freezing could cause serious heave and lift the pipe above the surrounding terrain. Landslides from global warming on steep slopes then could destroy the pipe.
The Canadian National Energy Board (NEB) may not approve the proposed project. One reason for this disapproval could be that there is an alternative, less challenging route across northern Canada that likely would provide significantly greater benefits to Canada and to high value markets in the Northeast U.S. Several individuals (the author included) plan to request that the NEB consider an alternative northern route.
The alternative route goes offshore through the Beaufort Sea, the Amundsen and Coronation Gulfs, crosses Nunavut to the Hudson Bay, then offshore again to the base of James Bay. From that point, the route goes south through unfrozen sediments to major Canadian and U.S. markets. An illustration with this article shows arctic ice content and the other shows a map of the alternative route to the Northeast U.S. that avoids dangerous discontinuous permafrost zones. The alternative route has the following advantages:
1. Its overland segment is likely thaw stable for most of the route with low ice content soils representing probably 10-20% of the route vs. 50% and more in areas of an Alaskan route. Not as many engineering, construction, and maintenance problems.
2. The route avoids all areas of dangerous discontinuous permafrost which maximizes the potential for continual ice build-up under a chilled gas pipeline and resulting heave.
3. Minimum thickness of active layer (coldest permafrost).
4. High percentage of the route is offshore (the safest place for an arctic gas pipeline).
5. Shortest distance to major gas markets. (Not dependent on expansion of other pipelines to reach the major markets).
6. Most favorable onshore terrain (avoids mountains, earthquake zones, major river crossings, steep slopes, forests and discontinuous permafrost zones.)
7. Low snowfall along land portions of route (less construction downtime).
8. Less affected by global warming.
9. If the gas competes in New York, Montreal, and other eastern markets, it should obtain higher net-back wellhead prices. The route with the highest net-back price will result in the greatest long-term benefit to Alaska.
10. Lowest cost per mile and likely the shortest construction time.
11. Most efficient gas transportation (least fuel usage/mile).
12. Greater productivity per worker. Less unproductive portal-to-portal transportation time for workers.
13. Safest route for both workers and the pipeline.
A route across northern Canada offers major benefits. It would spur exploration and development of the northern arctic – perhaps the greatest benefit of all to Canada. Geologists believe considerable undiscovered gas exists in the Canadian arctic.
Permafrost exists under the Beaufort Sea. Note however, whereas onshore Alaskan permafrost has been warming since about 1860, the end of the little “ice-age,” any offshore permafrost under the sea bottoms has been warming for about 10,000 years (since the end of the last major ice age when the sea recovered previously exposed areas). Sea bottoms should be relatively stable.
Further, ocean currents will result in the gas reaching the temperature of the sea quite quickly. When the flowing gas temperature is the same as the sea temperature, neither thawing of any underlying ice nor heave from ice formation will occur. Quite frankly, offshore is the safest place to install an arctic gas pipeline. It avoids the extreme environmental dangers of an onshore arctic gas pipeline that result from the thawing of ice lenses or the freezing of water (heave).
Global warming will have no effect on an offshore pipeline but could cause landslides and destruction of an onshore pipeline when laid on steep slopes. Geologists have recorded more than 2,000 landslides in the Mackenzie Valley during the warming of the past 150 years, for instance.
Two major problems will arise from an arctic offshore pipeline. The first involves the narrow window of only a few months in the summer for laying pipe. This will require more lay barges and close scheduling. The second involves compressor station location. Because of winter sea ice, it will be necessary to place compressor stations onshore. The land area south of the proposed route extending east from Prudhoe Bay until just past the mouth of the Amundsen Gulf contains high ice content (ice lenses) soils. Heat from natural gas compressors could thaw the underlying ice lenses. A solution would be to dredge an L-shaped channel in from the coast and place the compressor station on a barge at the back of the channel. This would protect the station from the winter sea ice.
Onshore, across Nunavut, industrial helicopters could string the large-diameter pipe during the summer (for winter construction). Helicopter flights would be short and there would be up to 20 hours each day of light available to place the pipe. For large-diameter pipe, this could be cheaper than building roads to string the pipe using flatbed trucks. Note that whereas a flat-bed truck can carry 40-50 joints of 10-inch diameter pipe, it can carry only one joint of 56-inch or 60-inch diameter pipe.
Onshore compressor stations could be designed with removable roofs for helicopter transportation of all components to the site for assembly. For maintenance, a helicopter and crew could remove the roof, replace any ailing component, and reinstall the roof in one trip. It might even be possible to avoid building ice roads for winter pipe laying. Because of the treeless terrain, low snowfall and gentle slopes, arctic tractors could move the pipe laying equipment, pull portable sleeping and recreation quarters for the crew that move with the construction site, and bring in food and supplies as needed. Wasted, non-productive, transportation hours for workers receiving portal-to-portal pay would be minimal. In short, laying pipe across a frozen, road-less terrain can be resolved with some ingenuity and advance planning.
The cost of a gas pipeline extending directly to the major eastern markets in Canada and the U.S. cannot be compared to the cost of a pipeline to Edmonton. A valid comparison requires that the cost of looping or providing additional capacity to transport gas downstream from Edmonton to U.S. markets also be considered.
The perceived stability of the sea bottoms and the low ice content (pore ice) of the overland route across Nunavut suggests that an ambient-temperature pipeline might be possible, at least for part of the route. This would significantly reduce the cost of the pipeline compared to a chilled-gas pipeline requiring refrigeration units at each compressor station. Coring and testing would be required to test such a thesis but the cost would be minor compared to the cost of refrigerating the gas to prevent the thawing of the underlying and surrounding ice. The possibility of a lower cost, ambient-temperature pipeline (rather than a chilled-gas pipeline) is an intriguing question that deserves an answer.
A northern pipeline route would provide winners, some losers and many perceived losers compared to a pipeline through Alaska to Edmonton. Winners would clearly be Canada as a whole, the U.S. industrial Northeast, Alaska and the gas producers receiving a greater netback to the wellhead.
Losers would be (1) citizens of Alaska hoping for employment during construction through Alaska, (2) similar individuals in Western Canada hoping for the same employment benefits, (3) pipeline companies currently moving gas from Edmonton, hoping to benefit from expanding their lines and carrying additional gas, and possibly (4) TransCanada Alaska and Foothills which are hoping to build the line from Prudhoe Bay to Edmonton – although they could earn more by joining a consortium to build a line along a northern route.
Perceived losers would be citizens of the western and central U.S. who believe that additional gas flowing to their regions would provide them a long-term benefit.
There is an old Chinese curse “May you live in interesting times.” The problem of how best to bring arctic gas south to Canadian and U.S. consumers is going to create interesting political and technical questions for the NEB and the U.S. Federal Energy Regulatory Commission (FERC) to consider. Canadian and U.S. citizens can only wait to learn what route arctic gas finally takes when it flows south. Someday it will.
(Author’s Note:A longer, more detailed and technical version of this article can be viewed at the author’s blog. The author can be reached at firstname.lastname@example.org.)
Philip L. Essley, Jr., is a retired petroleum engineer. He served as the lead technical adviser to the U.S. Office of Management and Budget when the OMB set up the Office of Federal Inspector to oversee construction of the Alaska Natural Gas Transportation System (ANGTS). The portion of the ANGTS that would have extended from Prudhoe Bay to Edmonton was not built. The Western Leg and Northern Border portions were built. He also served in the following roles: technical adviser to the U.S. Secretary of Energy for the ANGTS; lead engineer for the FERCduring the ANGTS application; and deputy director, FERC economic group. He also served as leader of the FERC “Need for Power Study” of the proposed Susitna Dam in Alaska. The dam was not built but, in 2008, a move was started in Alaska to resurrect the project.