Tar sands production near Fort McMurray, Canada, photo: sbamueller/Creative Commons
For politicians in Alberta and a handful of western US states the so-called unconventional oil source known as oil or tar sands and oil shale is the energy trump card. As conventional petroleum resources continue to dwindle these vast energy reserves promise both profit and power--politicians and companies on both sides of the 49th parallel are enthusiastic. However, when it comes to environmental protection and combatting climate change, this enthusiasm is entirely misplaced. NOTE: Whether one uses the term tar sand or oil sand often depends on the attitude of the user towards the substance, especially so in recent years. Though referring to the same thing, 'tar sands' has a darker connotation, with producers and supporters increasingly using 'oil sands', seemingly to rebrand them after negative publicity. For the remainder of this article tar sands will be used, as much as for ease of reading in distinguishing them from oil shale as anything else.
Where Are Tar Sands & Oil Shale Found?
Though the environmental impact of producing tar sands and oil shale are similarly bad (we'll get to those), there are not the same thing and are found in different geographic locations.
Bitumen is a thick, sticky form of crude oil, so heavy and viscous (thick) that it will not flow unless heated or diluted with lighter hydrocarbons. At room temperature, it is much like cold molasses.
To give you another visual, the word bitumen can generally be used interchangeably with asphalt. Asphalt roads consist of an aggregate bound together with bitumen.
Though found in a number of countries in the world, Canada and Venezuela hold the majority of deposits, though the latter's are normally referred to as 'extra-heavy crude' as it does flow more easily than the Canadian reserves in Alberta.
In total, just Canadian and Venezuelan supplies of bitumen contain about 3.6 trillion barrels of oil, about twice as much as all the known reserves of conventional oil in the world. Keep in mind, that total for bitumen doesn't mean that all of that can be technically or economically recovered, just what's in the ground.
Currently tar sands account for about half of Canada's oil production, which in turn is the single largest source of oil imports for the United States.
Oil shale, by contrast, is a fine-grained sedimentary rock containing kerogen, from which liquid hydrocarbons can be extracted. A number of nations have established oil shale industries, but the world's largest reserves (62%) occur in geologic formations in Colorado, Utah and Wyoming, largely on Federal land.
The estimated amount of recoverable oil from all the world's oil shale deposits is 2.8 trillion to 3.3 trillion barrels. As with tar sands, a lot more than the conventional sources of oil left.
How Are Tar Sands & Oil Shale Processed?Though conventional crude oil production and use certainly has plenty of negative environmental impacts, it's the production of these unconventional oil sources that really set them apart in terms of ecological destruction.
Because of its consistency, oil cannot be extracted from tar sands like it normally is. With tar sands you first either need to strip mine the substance from the ground or extract it in situ by injecting substances into the ground to reduce the viscosity so it will flow. These can be steam, solvents, or hot air.
Once extracted, everything that isn't the bitumen has to be removed, it has to be purified using a catalyst, and it has to go through a hydrogenation process. As you might imagine, this is all quite resource intensive, but we'll get to that in a moment.
Oil shale production takes a different path: First the oil shale has to be mined (either through open pit of strip mining, or underground mining). Then it has to be processed, though pyrolysis, to concert the kerogen into shale oil (a synthetic crude oil) and oil shale gas. This is generally done above ground, and often not at the mine location, though in situ methods of processing exist.
In either case though the resource intensity and production methods are such that there's much greater environmental impact that conventional petroleum production.
How Bad Is The Water Usage & Carbon Emissions?
Exactly how much more environmentally damaging tar sands and oil shale are compared to conventional petroleum sources depends on many production factors (on both sides, conventional petroleum is hardly clean), but it's safe to say, as WWF does, that the environmental costs are pretty much 'unthinkable'.
Starting with the greenhouse gas intensity: Conservatively, a barrel of fuel produced from oil shale emits 1.2 to 1.75 times the greenhouse gases as does a conventional barrel oil, with some estimates going as high as eight times the emissions. Tar sands extraction produces about three times the emissions.
In terms of energy returned on energy invested, oil shale is about 1:1 or 2:1 at best. In other words, it takes at best one additional unit of energy to produce one from oil shale and at worst you're not getting any additional energy out, just essentially transmuting the form of it.
Water intensity of both are high as well: For each barrel of oil produced from oil shale it takes 1-3 barrels of water on the conservative side and 2-5 with more liberal estimate; and that water is needed in areas of the United States already stressed for water and only likely to become more so in coming years. Tar sands require about three barrels of water for each barrel or oil, with that water coming from rivers. Once diverted it cannot be returned as it's too toxic and must be stored in tailing ponds, with loud bird-scaring beacons nearby so that the birds don't land on the water and die. Water quality issues downstream are also problematic, with recent studies linking pollution squarely to tar sands projects.
In this video Greenpeace International Executive Director Kumi Naidoo flies over the Alberta tar sands. You get a good look at toxic tailing ponds and the environmental destruction.
So What Should We Do?
Considering the undeniably great amount of energy tar sands and oil shale deposits contain, you may be tempted to think that we ought to plow forward with them and try the best we can to mitigate the damage. After all, having such large energy sources so close to hand and with a neighbor we trust is a decided advantage geopolitically.
But consider what eminent NASA scientist-turned-reluctant activist Dr James Hansen says about them. In short, leave all of it in the ground:
The simple message is the oil sands may appear to be gold. We do need energy and there's a lot of potential energy in the oil sands...But it is fool's gold because it's going to be clear and understood within a reasonably brief period of time that we cannot exploit unconventional fossil fuels like tar sands and tar shale. If we do, we're going to have to suck the CO2 back out of the atmosphere and the estimated cost of doing that is $200 to $500 a tonne of carbon.
We should not develop the unconventional fossil fuels. Those fuels - coal and tar sands - are so dirty and have such large regional negative consequences that it only makes sense to leave them in the ground. (Globe and Mail)
Hansen concludes, linking quite rightly I think, environmental damage and social justice: "The whole issue, carbon dioxide and climate, is a matter of intergenerational justice where the current generation is getting the benefit of burning the fossil fuels and the consequences occur primarily with young people and future generations just because...it takes time for the largest effects to occur."
Considering that where the majority of these fuels are produced and will ultimately be used are in two of the top three carbon emitters per capita, as well as the highest consumers of natural resources in the world, the issue of social justice and social equity become more pronounced. We are not talking here about greater energy being used to uplift people and improve standards of living, we are talking about continued and expanded pollution to uphold already ecological unsustainable economies.
The answer is to forgo the energy contained in tar sands and oil shales, invest in renewable sources of power, and should there be future shortfalls accept those constraints.
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More on Tar Sands & Oil Shale:
National Geographic Slams Tar Sands - Canadian Politicians Pissed
Canadian Tar Sands Look Like Tolkein's Mordor Says UN Water Advisor
Tar Sands Projects Responsible for Water Pollution in Alberta's Rivers - Despite Industry Claims to Contrary
Alberta Tar Sands Oil Flows South As Keystone Pipeline Opened
Exploiting Utah's Oil Shale Deposits is Fossil Foolishness (Video)
What's the Energy, Water and Greenhouse Gas Intensity of Oil Shale? High, High & High