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.

Extraction
Upgrading Venting and flaring Refining* Transport   and Distribution* Combustion* Total

Oil sands emissions estimates

Low 7.3 8.6 0.0

7.0

1.9 73.4 98.2
High 37.3 0.0 3.3

7.0

1.9 73.4 122.9
Most likely 23.5 0.0 1.5

7.0

1.9 73.4 107.3

EU conventional oil emissions estimates

Low 1.0 0.0 0.0

7.0

1.9 73.4 83.3
High 21.1 0.0 0.0

7.0

1.9 73.4 103.4
Most likely 4.8 0.0 0.0

7.0

1.9 73.4 87.1

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.

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

  1. What should Canada’s position be on the EU and oilsands

    [...] Let’s start with what the FQD implementation directive does.  Lifecycle emissions benchmarks are speculative, since actual emissions will depend on how a specific barrel was produced, refined, stored, and combusted, what fuel sources were used to provide additional energy at each step of the process, and how by-products are used.  The FQD attempts to lower the regulatory burden on refiners by providing default factors for feedstocks used – if you are supplying gasoline derived entirely from conventional oil (you can look here to see where EU oil comes from) then your fuel is treated as having 87.5gCO2e/MJ, or 2.81kg/l. If you use oilsands crude as your refinery feedstock, then your default value is higher – 107 gCO2e/MJ or 3.44 kgCO2e/l.  If you are trying to reduce your kgCO2e/l, you can see where the incentives will lead you – toward fuels labeled conventional and away from fuels labeled oilsands. (You can look here for a math lesson on life cycle analysis.) [...]

  2. Dan Wolfe

    You know I can’t resist checking your math… Turns out the part I thought was wrong is right: 31 liters of gasoline to get a GJ of energy! Hard to believe that we only pay about $4 for the same energy in natural gas. Why is there not more of a push to natural gas in vehicles? I did find a mistake though, your intermediate number of 0.3216 GJ per litre of gasoline is off by a decimal place – it should be 32 MJ or 0.032GJ per litre of gasoline.

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