Third IMO Greenhouse Gas Study 2014

86 Third IMO GHG Study 2014
Table 31 – Upper range of top-down fuel consumption by vessel type (million tonnes)
Fuel type 2007 2008 2009 2010 2011
MDO 71 73 77 64 73
HFO 258 258 245 256 244
All fuels 329 331 321 319 318
Fuel type 2007 2008 2009 2010 2011
MDO 22% 22% 24% 20% 23%
HFO 78% 78% 76% 80% 77%
All fuels 100% 100% 100% 100% 100%
The Third IMO GHG Study 2014 acknowledges that additional uncertainty about marine fuel sales to
consumers is not identified in the IEA data and cannot be quantified. For example, some ships that purchase
fuel (probably domestic and almost certainly MDO) are identified by IEA as “transport sector”. This includes
fuel purchased in places that might not be counted as “marine bunkers” (e.g. leisure ports and marinas). The
quantities of fuel sold to boats in a global context appear to be small compared to the volumes reported as
bunker sales but this cannot be evaluated quantitatively. Given that these sales are all domestic, the additional
uncertainty does not affect estimates of international shipping fuel use. However, uncertainty in the HFO/
MDO allocation may be slightly affected but remains unquantified; again, this analysis suggests such fuel
allocation uncertainty appears to be small.
Export-import discrepancy represents the primary source of uncertainty, as measured by the quantity of
adjustment that is supported by our analysis. This discrepancy exists because the total fuel volumes reported
as exports exceeds the total fuel volumes reported as imports. Evidence associating the export-import
discrepancy with marine fuels includes the known but unquantified potential to misallocate bunker fuel sales
as exports, as documented above. The magnitude of this error increased during the period of globalization,
particularly since the 1980s. In fact, the percentage adjustment due to export-import allocation uncertainty
has never been lower than 22% since 1982, as discussed in Annex 4. Table 32 and Figure 63 illustrate the
top-down adjustment for the years 2007–2011. During these years, the average adjustment due to exportimport
allocation uncertainty averaged 28%.
Table 32 – Results of quantitative uncertainty analysis on top-down statistics (million tonnes)
Marine sector 2007 2008 2009 2010 2011
Total marine fuel consumption (reported) 249.2 243.7 235.9 253.0 253.5
Adjustment for export-import discrepancy 71.5 79.4 78.0 59.0 56.0
Adjustment for fuel transfers balance 8.1 8.1 7.5 7.5 8.2
Adjusted top-down marine fuel estimate 329.8 331.2 321.4 319.5 317.7