Trans RINA, Vol 153, Part A4, Intl J Maritime Eng, Oct-Dec 2011 Panamax U-Panamax
Average Dwt 78,910
86,896 Average
kW/knot/Dwt 0.00938 0.00891
Table 11: Total installed power per knot per deadweight in modern bulk carriers6
In crude averages the new class permits 10% greater deadweight to be carried for a 5% reduction in powering requirements 13.
IMO undertook analysis of ships’ operations to obtain data on actual service speed compared to design speed. For bulk carriers with a design speed of around 14 knots the actual service speed was found to be 12.8 knots. Assuming this service speed the required main engine power for the two ships listed in Table 11 can be estimated by multiplying the factor shown in the table by speed and deadweight, with the results for average ships as follows:
Panamax U-Panamax
Average Dwt 78,910
86,896
ME Power kW
10,362 10,839
Table 12: Estimated average main engine power for Panamax bulk carriers
The relationship between power and fuel consumption has been analysed using data from LR, as presented in figure 14.
The resulting estimate for fuel consumption and fuel consumed per tonne mile is shown in Table 13.
Average ME fuel
consumption (tonnes per day)
Panamax 33.1 U-Panamax 34.5
Average fuel consumed per tonne mile (kg)
0.00125 0.00118
Table 13: Estimated main engine fuel consumption for panamax bulk carriers
The resulting reduction in fuel consumption per tonne mile for the U-Panamax ship is 5.4%, achieved by virtue of the improved hull form.
The IMO estimated that bulk carriers of this class consumed 13.314 million tonnes of fuel oil for main engine power in 2007 and on the basis of the saving
13 Looking more closely the potential savings depending on the efficiency of design could be significantly greater than this. A more detailed study to confirm this finding is currently underway as well as assessing the implications with respect to the IMO Energy Efficiency Design Index, EEDI.
©2011: The Royal Institution of Naval Architects
above the sector could have saved around 714,000 tonnes (5.4% of the total). The emission factor for the production of CO2 proposed by IMO is 3.13 tonnes of CO2 produced for every tonne of residual fuel oil burned and on this basis the amount of CO2 that could have been saved over the year is around 2.23 million tonnes. This is equivalent to around 0.26% of the total estimated production of around
870 million tonnes CO2 by
international shipping over the year. Reduction in other pollutants will be pro rata according to their relevant emission factors [24].
This saving is from dry bulk
carriers alone and it should be kept in mind that this is only one
of a range of ship types constrained by
Panamax beam, as discussed earlier in this paper. The total saving from all types due to improved hull forms is clearly likely to be considerably higher than this.
8.2 REDUCTION DUE TO INCREASED SHIP SIZE
The greater saving in dry bulk carrier fuel consumption will stem over the longer term from the potential to increase the average size of ships operating in this sector, as discussed in Sections 5.2 and 5.3 above. The 110,000 dwt vessel postulated as a future possible size of “Panamax” dry bulk carrier yields a 16% saving in ME fuel
consumption per tonne mile over today’s
conventional Panamax. This would yield a saving of 6.7 million tonnes of CO2 based on fuel used in 2007, around 0.8% of the total produced by international shipping over the year. Again this is the potential from the dry bulk sector only and other ship types will also yield gains.
8.3 TOTAL POTENTIAL CARBON SAVING This
is recommended for further study, taking into
account all ship types and trades. Savings will stem in total from:
improved hull forms for the ship types listed in Table 8, reducing fuel consumption;
larger ships being deployed on the shortened route, reducing the carbon production per tonne- mile of cargo carried;
Greater quantities of cargo moved through the canal, reducing the total tonne-mile sum in global trade.
8. CONCLUIONS
There are clear signs from the market that shipping advantage will be pursued in the dry bulk sector through increasing
ship size. The
constraint for bulk carriers transiting the Panama Canal presents an opportunity to construct larger ships with more efficient hull forms, gaining both economy of scale and significantly improved fuel efficiency.
relaxation of the beam
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