Total energy consumption 60000 101 50000 145 40000 180
30000 51861 20000 41244 41244
10000
0 Steel Aluminium Fuel consumption Manufacturing, recycling, and recovery Figure 8. Energy consumption 13. SENSITIVITY ANALYSIS
Varying certain parameters during a sensitivity analysis [1] affects the break-even points of the different ships.
The additional weight savings on the composite version are not a farfetched scenario, they are by all means passable. This will lead to less fuel consumption and minimises the costs thereby incurred. The
consumption of this optimised composite vessel is below the one of the aluminium version.
A further decrease of the carbon fibre price, which can be expected in the future, will obviously be advantageous for a composite ship.
Maintenance costs have the most interesting influence on the break-even points, since they appear
repeatedly.
Increasing the maintenance costs of the hull structure of the composite vessel shifts the break-even point towards the end of the vessel’s life. However, the composite version still becomes more profitable after less than twenty years of operation.
A variation of the inflation and interest rates can lead to both, an earlier or a later break-even point of the composite version compared to the others. The result changes are small and all reasonable assumptions for inflation and interest rates cannot affect the general statement of this study.
The life span of the different version must be taken into consideration too. To get comparable numbers it is set to 25 years. The composite ship is estimated to be in service up to 30 or even 35 years, while calculating with 25 years might be rather optimistic for an aluminium ship of that size, since
fatigue is expected to become an inconvenience towards the end of its operational life. ©2008: Royal Institution of Naval Architects B-9
However, at the time there are attempts in Europe to limit metal vessels’ life span, which may emphasise advantages of a ship built of fibre reinforced sandwich structures.
energy
As with any life cycle cost analysis or energy assessment, the figures presented in this paper are to be handled with care. The results heavily depend on the input data, which is frequently based on assumptions and estimated figures of complex processes.
REFERENCES [1]
Composite
B. Lingg, S. Villiger, (2002) “Energy and Cost Assessment of a High Speed Ferry in a Life Cycle Perspective” Master Thesis, KTH Stockholm. Skrift 2002-19a
[2] B. Lingg, S. Villiger, (2002), “Energy and Cost Assessment of a High Speed Ferry in a Life Cycle Perspective – Preliminary Design” Master Thesis, KTH Stockholm. Skrift 2002-19b
[3] A. P. Mouritz, E. Gellert, P. Burchill, K. Challis, (2001), “Review of advanced composite structures for naval ships and submarines” Composite Structures, 53, pp 21-41
[4] D. G. Woodward, (1997), “Life Cycle costing – theory, information acquisition and application. International Journal of Project Management”, Vol. 15, No. 6, pp 335-344
[5] B. S. Blanchard, W. J. Fabrycky, (1998), “System Engineering and Analysis” Prentice-Hall, Inc., New Jersey, USA
TJ
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