|Examples of emerging oil sands related technologies and trade-offs. Credit: ACS, Bergerson and Keith. Click to enlarge.|
Although it is technically possible to make deep reductions
in oil sands well-to-tank greenhouse gas emissions through the use of technologies such as carbon capture and storage (CCS) and the co-firing of biomass with fossil fuels for process heat or hydrogen, it is unclear if such a strategy
makes sense, Joule Bergerson and David Keith at the University of Calgary suggest in a paper published online 12 August in the ACS journal Environmental Science & Technology.
The paper is an examination of how various choices about the
scale of the life cycle analysis applied to oil sands (i.e., system boundaries) determine the emissions estimates, the technologies available to reduce
emissions, and perspectives and strategies of stakeholders. Bergerson and Keith pay particular attention to CCS, showing how divergent views about its cost effectiveness emerge from divergent choices about the scale of analysis.
|“Debate about the future of oil sands development is so
contentious that even the name of the resource is disputed:
proponents typically use oil sands while opponents use tar
sands. We use oil sands not to express our views on the debate,
but because tar is technically incorrect because tars are
products of biomass combustion and are chemically distinct
from bitumen. The source material is neither oil nor tar but
bitumen, but is most generally described as an example of
|—Bergerson and Keith|
The authors note that while some sources claim that the oil sands are up to 5 times more emissions intensive than conventional oil, others claim that they are as low as 10% more intensive. Both those claims can be defended, with the discrepancies arising “from an artful choice of the scale of analysis.”
The core of the discrepancy is whether or not the energy intensity and GHG
emissions are measured from the well-to-tank (WTT) or over
the full life cycle (well-to-wheels [WTW], from extraction of
the resource through to the use of the fuel in a vehicle). About 60-80% of full life cycle emissions result from driving/operating a vehicle; if only the extraction
emissions (WTT) are examined, oil sands will deliver a relatively high value.
A recent study by Bergerson and Keith’s group at the university (Charpentier 2009) reviewed published literature and concluded that while the extraction energy intensity and GHG emissions associated with oil sands are typically higher than those of conventional production, “it is not inconceivable that an oil sands pathway
may perform better than a conventional oil pathway, under
They also note that if the scale of analysis is that of the entire economy, the
value commonly referenced for economy wide emissions is
that oil sands constitute ~5% of Canada’s emissions. However, this only
accounts for the processing that occurs in Canada and
therefore excludes much of the refining and transport
emissions. Nor does this estimate include the use of
transportation fuels in vehicles, which occurs throughout
North America (NA); approximately two-thirds of oil sands
products end up in the US. All told, they wrote, the well-to-wheel (WTW) emissions
of oil sands products constitute roughly 2% of total emissions
in Canada and the US.
While oil sands emissions have more than doubled from 1990 to 2006, the absolute increase in emissions from oil sands over the same period is less than the absolute increase in Canadian electric or transportation sector emissions, and far less than
the increases in these sectors on a North American basis, they note.
Furthermore, they write, if the relative cost of cutting emissions was high
in a given sector, then growing emissions alone would not
solely justify major focus on cutting in that sector alone. In
Alberta, for example, CO2 emissions from coal-fired electric
power exceed emissions from oil sands and the costs of
reducing emissions from coal electricity are lower. Yet, coal-fired
emissions in Alberta receive relatively little attention
from environmental organizations and the public.
In addition, oil sands are a nearly unique emissions source in the global energy system; investments (money and political capital) in stopping oil sands emissions cannot easily be transferred to stopping emissions elsewhere, unlike technologies to reduce emissions from coal-fired power.
Why then the focus on oil sands? One reason it makes
strategic sense to focus on oil sands is that they represent
the world’s first major step into extra-heavy unconventional
oil. Without strong climate policy, one might expect production
of unconventional hydrocarbon fuels to increase dramatically
in the coming decades as supplies of conventional
oil become gradually tighter. A growing supply of unconventional
transportation fuels would tend to moderate oil
prices and would drive up emissions on a life cycle basis.
Moreover, slowing or halting the development of oil sands
and similar unconventional fuels such as coal-to-liquids will
tend to push up prices for fossil transportation fuels easing
the introduction of alternatives such as electric vehicles or
biofuels. There is, therefore, a sensible strategic reason for
ENGO’s to devote substantial efforts to stopping the development
of oil sands, efforts that are not directly related to
their current environmental impact.
…The cost of reducing these emissions will be
high compared to emissions reductions achieved elsewhere
in the economy. The environmental impacts of CO2 emissions
are the same wherever they occur, so seen through the lens of
environmental cost-benefit analysis it makes little sense to
devote major resources to reducing oil sands process emissions.
Resources might be better spent on the long-run task of
developing technologies that can decarbonize the transportation
sector by moving it away from oil as a primary fuel.
We hope that developing better public domain life cycle analysis
of the technical potential, costs, and environmental impacts of
oil sands technologies along with transparent methods to
describe the trade-offs involved in decarbonizing the transportation
sector will help clarify the messy interaction of strategic
interests and contradictory claims at play in the oil sands debate,
increasing the chance of choosing an economically sound path
to a carbon-neutral future.
—Bergerson and Keith
Joule A. Bergerson and David W. Keith (2010) Does carbon capture and sequestration (CCS) make sense in the oil sands? Environ. Sci. Technol. 44 (16), pp 6010–6015 doi: 10.1021/es903812e
Life Cycle Assessment of Oil Sands Technology (University of Calgary and University of Toronto)
Charpentier, A. D.; Bergerson, J. A.; MacLean, H. L. (2009) Understanding
the Canadian oil sands industry’s greenhouse gas
emissions. Environ. Res. Lett. 4 014005 doi: 10.1088/1748-9326/4/1/014005
Joule A. Bergerson and David W. Keith (2006) Life Cycle Assessment of Oil Sands Technologies (Paper No. 11 of the Alberta Energy Futures Project)