Math Lesson #2: Life Cycle Assessments and Oilsands: don’t just say dirty oil, know what it means.

The only thing more delayed than the EU’s decision on oilsands and their fuel quality directive is my blog post on the EU’s fuel quality directive and oilsands. This isn’t it…but it’s a start.  For now, you get more math, mostly for my future reference, but some of you may find it useful as well. What you’ll see is that the question of life cycle assessment of oilsands crude has a lot of assumptions behind it, and it’s worth understanding if you’re going to wade into the debate. If you want to learn a bit more about them, read on…

In reading background information on the EU’s proposed amendments to the their Fuel Quality Directive, it is again striking to me how impenetrable the units are. Take, for example, this consulting report prepared for the EU. Most of the units used for well-to-wheels GHG are (gCO2eq)/MJ (LHV) – total emissions, normalized based on global warming potential to grams of CO2 equivalent, per megajoule of heat released during combustion of the gasoline.  LHV, or lower heating value, is a measurement standard for calculating the energy content of the fuel.

For example, using an LHV calculation, gasoline contains 0.1154 million Btu per gallon of gasoline. Using a conversion of 3.7854 liters per gallon, I get .03048545 MM Btu/liter. 1 MMBTU is equivalent to 1.055 GJ, so we have 0.03216 GJ of energy per liter of gasoline calculated at LHV.  If you invert that ratio, 31.09 liters of gasoline contain 1GJ of energy, or 1000 MJ of energy.  If you had an oil barrel (158.9873 l) of gasoline, you’d have 5113.374 MJ of energy ready for your Prius.

So, back to oilsands – the EU’s proposed fuel quality directive would classify all oilsands-sourced crudes as having 107gCO2eq/MJ of wells-to-wheels emissions.  This translates to 3.44kg CO2e/l of gasoline.  According to the EU’s benchmarks, a liter of gasoline produced from conventional oil would have 18% less at 2.814kg CO2e/l.

The table below, sourced from Brandt (2011) shows how that estimate is broken down.

The key question most will ask is whether these numbers make sense.  The short answer is that they are in the right range, but that it’s hard to bundle oilsands into a single category.  According to a Jacobs Consultancy report compiled for the Alberta Energy Research Institute, SAGD production which undergoes an intermediate upgrading to synthetic crude will have higher emissions embedded in the end product (RBOB blendstock) of up to 118.9g/MJ (3.82 kg CO2e/l), while mined oilsands shipped as dilbit and refined to gasoline can have embedded emissions as low as 105.4g/MJ (3.4kg CO2e/l).  The key issue that Alberta producers will have, and rightly so, is that many non-oilsands crudes have comparable emissions.  For example, Bonny Light from Nigeria (106.4/MJ) or California thermally extracted heavy oil (113.5g/MJ) are comparable to oilsands crudes. You can see the range of oilsands emissions to other crudes in the Figure below, taken from the Jacobs report.

One key issue with life-cycle assessments which is relevant for oilsands is that you need to follow some of the other outputs of oilsands production and decide how those are to be included in the assessment.  With oilsands, a key component in the emissions assessment is the treatment of cogeneration.  If you assume that cogeneration displaces electricity which would otherwise have been generated by coal and natural gas, the emissions footprint is reduced significantly on a life-cycle basis, as shown in the Figure below, also sourced from the Jacobs report.

Of note, with full credit for cogeneration, all types of oilsands production would fall below the EU’s FQD benchmark.

So, two things to take away – there’s lots more math where this came from, and the story is much more complicated than those simply saying “dirty oil” over and over again would suggest.  Now, off to write that blog on Canada and the FQD.