ENSAYOS IN VITRO

volumes on the North Sea will not necessarily result in similar growth in energy use. The assumptions on future improvements in transport efficiency by North Sea shipping in the current study were derived from the second IMO greenhouse gas study (Buhaug et al., 2009). Chapter 5 of the IMO study gives an overview of potential technological and operational measures for reducing fuel consumption and related emissions from international shipping. The study shows that the potential for energy savings and emission reductions is substantial. Combined, the different technological and operational measures can result in energy savings of up to 25% to 75% compared with 2007 levels, with the upper bound of the bandwidth requiring speed reductions and the use of low-carbon fuels and/or renewable energy.

In Chapter 7 of the IMO study, different scenarios are presented for future emissions from international shipping. The assumptions used within the different scenarios are derived from an open Delphi process based on expert opinion and analyses (Buhaug et al., 2009). The projected transport efficiency improvements in international shipping are subdivided into three elements: 1. efficiencies of scale

2. speed

3. ship design and operation.

For each of these factors, assumptions are made on developments between 2007 and 2020/2050. Because of

Table A2.1

Average annual growth rates of shipping in the North Sea (2009–2030, in tonne-kilometres)

Central case Lower bound Upper bound

Container shipping 3.5% 2.0% 5.0%

Other 1.5% 0.5% 2.5%

All ships 2.1% 1.0% 3.3%

Source: PBL

Table A2.2

Assumptions on efficiency improvements between 2007 and 2030 in current study (fleet averages)

Central case Lower bound Upper bound

Efficiencies of scale -4% 0% -14%

Speed -10% 0% -22%

Technological and operational improvements1 _{-10% -2% -14%}

All ships -22% -2% -42%

1) Excluding changes in ship sizes and operational speed

the uncertainties involved, a base case and a low and high estimate is presented for each factor. In the current study, we used the assumptions for the base case, as presented in Tables 7.11, 7.12 and 7.13 of Buhaug et al. (2009). These assumptions are presented in Table A2.2 and are described in more detail below.

Efficiencies of scale

The first factor, efficiencies of scale, relates to the size of the ships, with larger ships generally being more efficient per tonne-kilometre than smaller ships. The fleet projections for 2020 used by Buhaug et al. (2009) are derived from Lloyd’s Register–Fairplay Research. Between 2020 and 2050, no structural changes in the fleet are modelled. Based on the projections of Buhaug et al., we assumed an efficiency improvement of 4% by 2030, compared with 2007, due to the deployment of larger ships, with a bandwidth of between 0% and 14%.

Speed

The second factor, speed, has a major influence on the fuel efficiency of maritime shipping, with the propulsion power requirement being roughly proportional to the third power of speed. Reducing speed, therefore, may be very effective in reducing fuel consumption and related emissions. Cariou (2011) shows that a 55% reduction in fuel consumption can be realised by container ships when sailing speeds are reduced by 30%, although part of this will be compensated by the longer journey time which results in more days at sea for the same trip. Due to the longer journey times transport capacity will decline and more (or larger) ships will be required to transport the same amount of cargo.

In recent years, bunker prices have increased and transport capacity has grown faster than transport demand, due to the economic crisis. Therefore, slow steaming has become an attractive way to reduce operational costs and absorb part of the capacity surplus. MARIN (2011b) shows that the operational speeds of specifically the larger ships in the North Sea decreased significantly between 2007 and 2009, see also Figure 2.5. Cariou (2011) estimates that slow steaming in 2010 reduced worldwide shipping emissions by around 11%, compared with 2008 emission levels.

The surplus shipping capacity, however, expected to decline in the long term, with the expected economic growth leading to an increase in transport demand and with ordered shipping capacity being reduced to match demand. Therefore, it is assumed that the current reduction in operational speeds, as shown in Figure 2.5, is only temporary. However, some shipping liners have announced that they will continue with slow steaming in the future. Buhaug et al. (2009) assume a reduction in

sailing speeds of 5% by 2020 and 10% by 2050, compared with pre-crisis (2007) levels. Based on these figures, we used a 7% reduction in sailing speeds for North Sea shipping in 2030 compared with the 2007 (pre-crisis) levels, with a bandwidth of 0% to 17%. The bandwidth is derived from the upper and lower cases from Buhaug et al. (2009).

The impact of lower sailing speeds on power demand is modelled using a third-power relationship between speed and power as described in MARIN (2011b). The decrease in sailing speeds leads to a reduction in transport capacity, requiring a larger number of ships to transport the same amount of goods. This effect was also taken into account. The 7% reduction in operational speeds results in a 10% reduction in energy use in 2030 compared with 2007 (ceteris paribus). Since operational speeds already decreased in 2009 compared with 2007 due to the economic crisis, the reduction in energy use by 2030 is expected to equal approximately 7%, compared with 2009.

Ship design and operation

The third factor influencing the energy efficiency of maritime shipping relates to ship design and operation (excluding speed changes). Buhaug et al. (2009) present assumptions on expected efficiency improvements due to developments in ship design, technology and operation. It is assumed that only those improvements will take place that are cost-effective in the different scenarios. The assumptions also take into account that the short-term potential for improvement is rather limited because of the slow renewal of the fleet. The fleet average efficiency improvement due to improvements in ship design, technology and operations is assumed to be 2% in 2020 and 25% in 2050. Based on the figures, for 2030 an efficiency improvement is used of 10% compared with 2007 levels, with a bandwidth of between 2% and 14%. This bandwidth is also derived from the upper and lower cases from Buhaug et al. (2009).

Combined effect of efficiency improvements and new IMO measures

Combining the aforementioned assumptions on efficiencies of scale, sailing speeds and improvements in ship design and operation lead to an aggregate fleet- average efficiency improvement of approximately 22% in the base case in 2030 compared with 2007 levels, which means the average annual improvement is approximately 1%. The resulting bandwidth is 2% to 42%, which means approximately a 0% to 2% annual improvement. In July 2011, the Marine Environment Protection Committee (MEPC) of the IMO agreed on mandatory measures to reduce greenhouse gas emissions from international shipping in the form of the Energy Efficiency

81

Annexes | Design Index (EEDI) and the Ship Energy Efficiency

Management Plan (SEEMP) for all ships (IMO, 2011). The EEDI sets a minimum energy-efficiency level per tonne- kilometre for different ship types, applying only to new ships. This minimum level is tightened over time. The SEEMP provides insight into ship or fleet efficiency performance over time and urges ship owners and operators to review efficiency during each phase of operation and consider improvements to optimise the energy-efficiency performance of the existing fleet. Bazari and Longva (2011) estimate that both measures combined could lead to a 23% reduction in energy use in 2030 compared with business as usual. This is a slightly higher improvement than the combined effect of speed reductions and technological improvements assumed in the base case of this study, but falls well within the bandwidth.

Effects of IMO and EU legislation on emissions and