Third IMO Greenhouse Gas Study 2014

168 Third IMO GHG Study 2014
data sets included: Statcode3, Statcode5, gt, dwt, length, beam, max draught, ship speed, installed main
engine power, engine revolutions per minute (RPM), various cargo capacity fields, date of build, keel laid
date, propulsion type, number of screws, and main engine fuel consumption and stroke type. In addition to
technical data, the IHSF data set includes a ship status field that provides an indication if a ship is active, laid
up, being built, etc. The consortium had access to quarterly IHSF data sets from 2007 to 2012. Each year’s
specific data was utilized for the individual annual estimates.
It should be noted that the data sets do not provide complete coverage for all ships and all fields needed.
In cases where data are missing, values are estimated either from interpolation or from referencing another
publicly available data source. The details of the approach taken for the missing data and the technical and
operational data themselves are further discussed in Section 1.4.3 and in Annex 3.
For auxiliary engine operational profiles, neither IHSF nor the other ship-characteristic data services provide
auxiliary engine or auxiliary boiler utilization data, by ship mode. In the Second IMO GHG Study 2009,
auxiliary loads were estimated by assuming the number and load of auxiliary engines operated, by ship
class, and basing the rated auxiliary engine power on the limited data provided in IHSF. To improve on this
approach, the consortium used data from Starcrest’s Vessel Boarding Program (VBP) (Starcrest, 2013), which
had been collected at the Port of Los Angeles, the Port of Long Beach, the Port Authority of New York & New
Jersey, the Port of Houston Authority, the Port of Seattle and the Port of Tacoma. The VBP data set includes
over 1,200 ships of various classes. Starcrest has collected data on-board ships for over 15 years specifically
related to estimating emissions from ships and validating its models. Auxiliary load (in kW) are recorded for
at-berth, at-anchorage, manoeuvring, and at-sea ship modes. The ship classes that have been boarded as part
of VBP include:
• bulk carrier
• chemical tanker
• cruise ship
• oil tanker
• general cargo ship
• container ship
• refrigerated cargo ship.
For container and refrigerated cargo ships, ship auxiliary engine and boiler loads (kW), by mode, were
developed based on the VBP data set and averages by ship class and bin size were used. This approach
assumes that the ships boarded are representative of the world fleet for those same classes.
For bulk carriers, chemical tankers, cruise ships, general cargo ships and oil tankers, a hybrid approach was
used combining VBP data, data collected from the Finnish Meteorological Institute (FMI), and the Second IMO
GHG Study 2009 approach. The prior study’s approach was based on average auxiliary engine rating (kW),
assumption of number of engines running expressed in operational days per year (if greater than 365, it was
assumed that more than one engine was running), a single load factor for each ship class and capacity bins.
The hybrid method was used for ships boarded as part of VBP, but was considered not to be a robust enough
to use on its own. VBP data were used to compare estimated at-berth loads and the ratios between various
modes and to review the results for reasonableness of the estimates. The resulting ship-weighted auxiliary
loads estimated from this approach are presented in Table 6.