Third IMO Greenhouse Gas Study 2014

118 Third IMO GHG Study 2014
shipping NO x and SO x represent approximately 13% and 12% of global NO x and SO x totals respectively.
Comparisons with AR5 are also consistent with comparisons in peer-reviewed journal publications reporting
global SO x (Smith et al., 2011) and NO x (Miyazaki et al., 2012).
Multi-year averages for PM, CO and NMVOC are calculable but are rarely compared with global totals.
Moreover, AR5 only reports global values for CO and NMVOC, and IPCC reports substances of particulate
matter such as black carbon and organic carbon. Interested readers are referred to annex II of AR5 (IPCC,
2013) for tables with global totals for CO (AR5, Table All.2.16), NMVOC (AR5, Table All.2.17), organic carbon
(AR5, Table All.2.21) and black carbon (AR5, Table All.2.22).
2.4 Quality assurance and quality control of other relevant substances
emissions inventories
Because the input data and method for Section 2.1 and Section 2.2 have substantial similarity to the input
data and method for Sections 1.1 and Section 1.2, Section 2.4 is closely connected to Section 1.4. The two
areas where there is specific additional content are in the QA/QC of the emissions factors used and in the
comparison of emissions inventories obtained using the two approaches (bottom-up and top-down).
2.4.1 QA/QC of bottom-up emissions factors
As stated in Section 2.2.7, the emissions factors used in the Third IMO GHG Study 2014 were selected by
the consortium with first preference going to published IMO factors (e.g. NO x by fuel type). Other factors
were selected with the unanimous agreement of the emissions factor working group based on what various
members are currently using in their work. It should also be noted that emissions factors are typically derived
from emissions testing results and reported as energy-based (g pollutant/kWh) factors. Both the Second IMO
GHG Study 2009 and this study used fuel-based (g pollutant/g fuel) factors. The following observations can
be made about the comparison of the two sets of emissions factors:
• The Second IMO GHG Study 2009 emissions factors (presented in its Table 3.6) do not differentiate
for various engine types (SSD, MSD, HSD, auxiliary boilers, LNG Otto, steam, gas turbine), engine
tier (0, I, II) or duty cycle (propulsion, auxiliary). Exceptions to these are fuel type differentiation (CO 2 ,
SO 2 , NO x , PM 10 ) and auxiliary boilers (NO x ). The Third IMO GHG Study 2014 includes each of these
differentiations and further adjusts the emissions factors based on engine load.
Since the emissions factors are significantly more detailed in the Third IMO GHG Study 2014, comparisons
are somewhat difficult; however, they are compared in Table 68.