Thursday, November 11, 2010

Tar sands problems

Posted on Thu, Nov 11, 2010 at 4:00 AM

Until the world manages to change to CO2-free and carbon-neutral sources of energy, we have to use at least a small fraction of our fossil fuels to keep things going in the meantime. For that purpose some of our nation’s most prominent scientists suggest that we use only existing sources of gas and oil during this transition period, for two reasons. One is that these two fuels provide the least CO2 emitted per unit of energy produced. The second advantage (ironically) is that the reserves of these are thought to be limited (if we don’t look too hard for more) as is the total amount of CO2 that can be produced by them. With this approach, the upper level of atmospheric CO2 we will reach could be held to approximately 430 parts per million (ppm), of which then about 80 ppm would then somehow have to be removed, 50 ppm of which could come from improved land use.

So what’s wrong with burning coal instead of gas and oil? One problem associated with coal is the additional chemical pollution and physical disturbance its mining produces. Another is that it produces much more CO2 per energy unit derived than do gas and oil. An even greater problem associated with coal, however, is the fact that there is simply too darn much of it! If the world’s coal continues to be burned along with the readily available gas and oil previously mentioned, then atmospheric CO2 is sure to reach levels well over 500 ppm from which recovery is much more difficult to envision. While there is some possibility of capturing and permanently sequestering the CO2 emitted from coal-fired power plants, both the technical and financial feasibility of that possibility has not yet been demonstrated.

So what’s wrong with using the oil derived from the Alberta tar sands? The answer is lots of things, which make its use even worse than that of coal. Like coal, there is simply too much of it—the total amount of oil in the tar sands is comparable to that in the Middle east. Another is that the methods used for separating the oil from the tar sands produces an enormous amount of surface and water pollution. Another is that to separate the oil from the tar sands, a huge amount of natural gas, about 40 percent of Alberta’s total, is used to heat mixtures of water added to the tar sands. Thus, the production of this form of oil ends up producing far more CO2 than that of normal crude oil. Another is that vast boreal forested regions of Alberta will be destroyed in this process (we’re talking about 20 percent of Alberta, or an area the size of Florida!) which otherwise would be removing CO2 from the atmosphere. Finally and unlike coal, there is no way of capturing and sequestering the CO2 emitted in the processes of extracting, refining, and using the tar sands oil.

While we are at it, we should also consider the options of coal gasification and liquefaction plants that have been considered in Montana and used elsewhere. In terms of their environmental feasibility, they are approximately as bad as the tar sands, primarily because the feedstock used for these, coal, would last for centuries and because this technology offers no potential for the capture and sequestration of associated CO2 emissions.

In summary, there is great risk that the full development of the Alberta tar sands and the existing coal fields of the world, along with use of our existing supplies of gas and oil, would boost the temperature of Earth to levels beyond which our planet might find itself on an uncontrollable path of run-away feedback effects leading to a distinctly less human-friendly state. The contents of the long sentence I just wrote is now well known within the scientific community and is not “rocket science.” Therefore, I would encourage the governor to give greater consideration to these very possible long-term implications of our energy policies when considering what to do with our essentially endless supplies of tar sands and coal.

Eric Grimsrud

Emeritus Professor of Chemistry

Montana State University


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