Third IMO Greenhouse Gas Study 2014

Inventories of CO2 emissions from international shipping 2007–2012 61
Figure 43: OECD versus non-OECD data collection system
IEA acknowledges that challenges remain in collecting international marine bunkers data worldwide; however,
compared to other sources, the IEA database seems consistent across the years and is regulary updated.
According to Morel (2013), the revisions in the IEA international marine bunkers database have improved its
quality. The database published in 2012 covers 139 individual countries compared to the 137 of the 2007
database. Of these 139 countries, the 54 countries that represent 80% of the total sale have used official
energy statistics. Another six countries, representing 14% of the total sale, have used other sources, such as
port authorities, oil companies and data provided by FACTS Global Energy (http://www.fgenergy.com). Lastly,
in 2012 edition, data have been estimated for 33 countries that represent only 6% of the total sale, considering,
for example, residual GDP growth and marine traffic growth (Morel, 2013).
In addition to directly reported IEA marine fuel statistics, the consortium reviewed the energy balances of each
fuel to inform the uncertainty analysis for top-down marine fuel consumption in Section 1.5. This provides
QA/QC and enables an estimate of potential uncertainty around reported fuel sales for the marine sector
(domestic and international).
For example, corroborating information about the potential for under- or overreporting international marine
bunkers includes:
1 From Energy Statistics for Non-OECD Countries, IEA, 2009 edition: “For a given product, imports and
exports may not sum up to zero at the world level for a number of reasons. Fuels may be classified
differently (i.e. residual fuel oil exports may be reported as refinery feedstocks by the importing
country; NGL exports may be reported as LPG by the importing country, etc.). Other possible reasons
include discrepancies in conversion factors, inclusion of international marine bunkers in exports,
timing differences, data reported on a fiscal year basis instead of calendar year for certain countries,
and underreporting of imports and exports for fiscal reasons.”
2 From the OECD Factbook 2013: Economic, Environmental and Social Statistics (“Energy supply”, page
108) and the Factbook website: “Data quality is not homogeneous for all countries and regions. In
some countries, data are based on secondary sources, and where incomplete or unavailable, the IEA
has made estimates. In general, data are likely to be more accurate for production and trade than for
international bunkers or stock changes. Moreover, statistics for biofuels and waste are less accurate
than those for traditional commercial energy data.”
In summary, IEA and OECD identify specific types of error in energy data that involve marine bunkers. The
first is allocation or classification error involving imports, exports and marine bunker statistics. The second is
country-to-country differences in data quality, specifically related to poor accuracy for international bunkers
or stock changes. These insights helped inform the consortium’s direct QA/QC and uncertainty efforts.