Keystone XL: Game over?

Aside from the carbon from oil in-place, one needs to figure in the additional carbon emissions from the energy used to extract the oil. For in-situ extraction this increases the carbon footprint by 23% to 41% (as reviewed here ) . Currently, most of the energy used in production comes from natural gas (hence the push for a pipeline to pump Alaskan gas to Canada). So, we need to watch out for double-counting here, because our “game-over” estimate already assumed that the natural gas would be used for one thing or another. A knock-on effect of oil sands development is that it drives up demand for natural gas, displacing its use in electricity generation and making it more likely coal will be burned for such purposes. And if high natural gas prices cause oil sands producers to turn from natural gas to coal for energy, things get even worse, because coal releases more carbon per unit of energy produced — carbon that we have not already counted in our “game-over” estimate.

Are the oil sands really the “biggest carbon bomb on the planet”? As a point of reference, let’s compare its net carbon content with the Gillette Coalfield in the Powder river basin, one of the largest coal deposits in the world. There are 150 billion metric tons left in this deposit, according to the USGS. How much of that is economically recoverable depends on price and technology. The USGS estimates that about half can be economically mined if coal fetches $60 per ton on the market, but let’s assume that all of the Gillette coal can be eventually recovered. Powder River coal is sub-bituminous, and contains only 45% carbon by weight. (Don’t take that as good news, because it has correspondingly lower energy content so you burn more of it as compared to higher carbon coal like Anthracite; Powder River coal is mined largely because of its low sulfur content). Thus, the carbon in the Powder River coal amounts to 67.5 gigatonnes, far below the carbon content of the Athabasca Oil Sands. So yes, the Keystone XL pipeline does tap into a very big carbon bomb indeed.

But comparison of the Athabaska Oil Sands to an individual coal deposit isn’t really fair, since there are only two major oil sands deposits (the other being in Venezuela) while coal deposits are widespread. Nehring (2009) estimates that world economically recoverable coal amounts to 846 gigatonnes, based on 2005 prices and technology. Using a mean carbon ratio of .75 (again from Table 6 here), that’s 634 gigatonnes of carbon, which all by itself is more than enough to bring us well past “game-over.” The accessible carbon pool in coal is sure to rise as prices increase and extraction technology advances, but the real imponderable is how much coal remains to be discovered. But any way you slice it, coal is still the 800-gigatonne gorilla at the carbon party.

Commentators who argue that the Keystone XL pipeline is no big deal tend to focus on the rate at which the pipeline delivers oil to users (and thence as CO2 to the atmosphere). To an extent, they have a point. The pipeline would carry 500,000 barrels per day, and assuming that we’re talking about lighter crude by the time it gets in the pipeline that adds up to a piddling 2 gigatonnes carbon in a hundred years (exercise: Work this out for yourself given the numbers I stated earlier in this post). However, building Keystone XL lets the camel’s nose in the tent. It is more than a little disingenuous to say the carbon in the Athabasca Oil Sands mostly has to be left in the ground, but before we’ll do this, we’ll just use a bit of it. It’s like an alcoholic who says he’ll leave the vodka in the kitchen cupboard, but first just take “one little sip.”

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