[snootchiebootchies]

Originally Posted by delayedreflex

If the discrepancy is due to what I think it likely is, then there probably isn't a big under-reporting of industrial emissions from point-source facilities, but potentially big differences for other industries where the emissions are not easily correlated with the burning of fuel. I'd be curious if, for example, agricultural emissions and emissions impacts due to land-use changes could be better quantified using these newer measurement techniques.

This is absolutely correct. Emission estimates from combustion point sources are very accurate as they would involve simple stoichiometric calculations. The sources with great uncertainty and almost certainly under-reported are from large area or diffuse sources. The article is correct in saying oilsands facilities are following the required reporting methodology but it is also true that many oilsands facilities don't really want to know what they are not capturing in their reporting/measurements. Anybody in the business of reporting/measuring GHGs from oilsands facilities may dispute the actual numbers but they would not be surprised by the conclusions of this report.

These discrepancies are almost certainly due to the differences in tailings operations between the different sites as well as the limitations of current methods for measuring emissions off of those ponds. Not only can there be VOCs emitted from the ponds due to diluent losses to the ponds, biological action results in the breakdown of the residual hydrocarbons in the tailings and generation of methane. These emissions probably have huge variability to them due to changes in process conditions, pond conditions, climate, etc. From what I know about current measurement techniques for reporting emissions, they take a collection of point samples from around a pond maybe a few times a year, which seems like it would be massively inadequate for capturing the variability in the emissions.

Another large uncertainty is when tailings pond thaw during the spring and methane that have been accumulating for months under the ice is released to the atmosphere. There is nobody taking flux chamber samples during this particular phenomenon so nobody really knows how much gets missed.