Third IMO Greenhouse Gas Study 2014

Scenarios for shipping emissions 2012–2050 135
cannot be implemented simultaneously on a ship). The MACC takes into account that some measures can be
implemented on specific ship types only. It is also assumed that not all cost-effective measures are implemented
immediately but that there is a gradual increase in the uptake of cost-effective measures over time.
EEDI will result in more efficient ship designs and consequently in ships that have better operational efficiency.
In estimating the impact of EEDI on operational efficiency, this study takes two counteracting factors into
account. First, the current normal distribution of efficiency (i.e. there are as many ships below as above
the average efficiency, and the larger the deviation from the mean, the fewer ships there are) is assumed to
change to a skewed distribution (i.e. most ships have efficiencies at or just below the limit, and the average
efficiency will be a little below the limit value). As a result, the average efficiency improvement will exceed
the imposed stringency limit. Second, the fact that most new-build ships install engines with a better specific
fuel consumption than has been assumed in defining the EEDI reference lines is also taken into account.
The result of these two factors is that operational improvements in efficiency of new ships will exceed the
EEDI requirements in the first three phases but will lag behind in the third (see Annex 7 for a more detailed
explanation).
It is likely that improvements in efficiency will continue after 2030, although it is impossible to predict what
share of the improvements will be market-driven and what regulation-driven. Because of the high uncertainty
of technological development over such a timescale, two scenarios are adopted. One coincides with the
highest estimates in the literature (excluding speed and alternative fuels, which are accounted for elsewhere):
a 60% improvement over current efficiency levels. The second has more conservative estimates: a 40%
improvement over current levels.
3.2.7 Fuel mix: market- and regulation-driven changes
Two main factors will determine the future bunker fuel mix of international shipping:
1 the relative costs of using the alternative fuels;
2 the relative costs of the sector’s alternative options for compliance with environmental regulation.
The environmental regulations that can be expected to have the greatest impact on the future bunker fuel mix
are the SO x and NO x limits set by the IMO (regulations 13 and 14 of MARPOL Annex VI), which will become
more stringent in the future. This will also apply in any additional ECAs that may be established in the future.
In the emissions projection model, two fuel mix scenarios are considered, a low LNG/constant ECAs case and
a high LNG/extra ECAs case.
In the low LNG/constant ECAs case, the share of fuel used in ECAs will remain constant. In this case, it is
assumed that half of the fuel currently used in ECAs is used in ECAs that control SO x only, and the other half
in ECAs where both SO x and NO x emissions are controlled. In this scenario, NO x controls are introduced in
half of the ECAs from 2016 and in the other half from 2025. In this case, demand for LNG is limited.
The high LNG/extra ECAs case assumes that new ECAs will be established in 2030, doubling the share of fuel
used in ECAs. In this case, there is a strong incentive to use LNG to comply with ECAs. In Table 74, the fuel
mix is given per scenario.