addressing uncertainty in oil and natural gas industry greenhouse

GHG Emissions, tonnes/yr
60,000
50,000
40,000
30,000
20,000
10,000
0
Combustion Vented Fugitive Indirect
Emission Source Category
Carbon Dioxide
Methane
Nitrous Oxide
Other GHGs
Figure 5-1. Onshore Oil Field: Summary of Emissions
Figure 5-2 illustrates emissions for the facility with each emission category and each gas converted to CO 2 e,
using each gas’ GWP. It should be noted that although the GWP itself has uncertainty associated with it, this
report treats the GWP as a selected constant. Therefore, no uncertainty is associated or propagated from the
GWP values. Figure 5-2 also illustrates the bounds of uncertainty (at 95% confidence) for each emission
source category.
5.4.1 Opportunities to Improve the Uncertainty Estimate for the Onshore Oil Field
Each facility should examine the major categories of emissions and emission uncertainty, and then examine
specific emission sources within the category. Prioritizing the largest sources of uncertainty can be done with
this simple approach.
Among the major types of emissions in Figure 5-2, there are three very significant emission categories:
1) combustion sources of CO 2; 2) vented sources of CO 2; and 3) vented sources of CH 4 . These are the most
significant source of greenhouse gas emissions for this facility. Together they comprise almost 95% of all
GHG emissions from the facility.
Pilot Version, September 2009 5-20