Third IMO Greenhouse Gas Study 2014

Scenarios for shipping emissions 2012–2050 133
is assumed to grow if, given the projected productivity, the expected transport demand cannot be met by the
fleet. On the other hand, if, given the projected productivity, the expected transport demand could be met by
a smaller fleet, the active fleet is not assumed to decrease. This means that ships are assumed to reduce their
cargo load factor – i.e. become less productive – rather than being scrapped or laid up or reducing their speed.
The projection of ship productivity is based on the historical productivity of the ship types. For all ship types,
the 2012 productivity of the ship types is lower than the long-term historical average (see Annex 7 for more
details). This is assumed to be caused by the business cycle, rather than by structural changes in the shipping
market; this study therefore applies a future productivity development that converges towards the ship type’s
average productivity, reverting back to the 25-year 1 mean value within 10 years, i.e. until 2022.
The ship productivity indices used in the emissions projection model, which can be specified per five-year
period, are given in Table 71.
Table 71 – Ship type productivity indices used in emissions projection model
2012 2017 2022–2050
Liquid bulk vessels 100 113 125
Dry bulk vessels 100 102 104
Container ships 100 109 118
General cargo vessels 100 109 118
Liquefied gas carriers 100 106 113
All other vessels 100 100 100
3.2.5 Ship size development
In the emissions projection model, ship types are divided into the same ship size categories as in the emissions
inventory model. For the emissions projection, the future number of ships per size category has to be
determined.
The distribution of ships over their size categories can be expected to change over time according to the
number of ships that are scrapped and enter the fleet, as well as their respective sizes.
In the emissions projection model, it is assumed that total capacity per ship type meets projected transport
demand, that all ships have a uniform lifetime of 25 years and that the average size of the ships per size
category will not change compared to the base year 2012, while the number of ships per bin size will.
The development of the distribution of vessels over the size categories until 2050 is determined based on
a literature review, taking into account historical developments in distribution, expected structural changes
in the markets and infrastructural constraints. In Table 72 and Table 73, 2012 distributions and expected
distributions for 2050 are presented.
1
Due to a lack of historical data, for container vessels and liquefied gas vessels we take the average of the 1999–2012 period, i.e. a
13-year period.