Consequences of speed reductions for ships - An impact study for shipping companies and Swedish business

• Mandatory speed reductions have been proposed by different parties within the International Maritime Organization (IMO) as a short time measure to reduce the emissions of greenhouse gases from shipping. This study assesses what consequences it can have for Swedish shipowners and the Swedish business society that relies on maritime transportation in their supply chains. The most relevant IMO proposals for mandatory speed reductions are described in the study and from these a selected number of speed reduction proposals are analysed further. The speed that the vessels is operating at will affect the consumption of fuel per transport work and in many cases, a lower speed will also result in a reduced greenhouse gas impact per moved amount of cargo. The effects in total savings are higher for the speed reductions close to vessels design speed and will give lower savings the more the speed is reduced. The results show that the effects for a specific shipping company can be anything from minor towards an impact that makes the present business case unfavourable. The study cannot lay down that mandatory speed reductions will give all shipping companies severe negative effects, this as the effects will vary substantially, from positive to negative, depending on shipping segment, geographic market, modal competition and the design of the service. It is clear, though, that some shipping companies will be severely affected. When fuel savings from speed reduction is assessed, the relation between main engine power needed for propulsion and vessel speed reduction, Power = k*(v/v0)3 is often used; where v is the reduced speed and v0 the initial reference speed. This relation normally gives the correct correlation for smaller speed reductions but will overestimate the savings for larger speed reductions. A reason for the overestimates is that the fuel consumption in the main engines will not reach zero consumed fuel at zero speed (as the model indicates). Just the fact that the engines are running also at berth will consume fuel and, further, the engine and propulsion efficiency will decrease gradually when the system diverge from the speed for which the system is optimised for. The calculations in the case studies and interviews performed in this study indicate that some of the logistics service designs will require a totally different one in case that the speed is required to decrease. Such effects can be that the turnaround time is not efficient for the number of trips per day, or weekly service that the service is designed for. For other cases, the speed is already at such a low level, compared to the average for the vessel size and segment, that even relatively large speed reduction requirements will not require further reductions and hence not affect the operations at all. Other setups will instead lose competitiveness in comparison with competing road transport with an expected effect on modal shift towards road transport. The consumption and the related greenhouse gas emissions per transported amount of cargo seem for most of the analysed cases be possible to lower with reduced speed for the speed limitations under study. However, the cost per moved amount of cargo seems to be optimised at present speed and tends to increase in case of further speed reductions. This has been assessed with simplified economical calculations for a tanker and a RoRo vessel case, respectively. The interviews conducted among shipping companies give similar results as in the case study assessment: mandatory speed reductions will impose significant economical and logistical implications on ship-owners and their customers, especially in liner shipping. An often-discussed issue is the possible effects of more vessels needed to be built when speed is lowered. An assessment performed for a Panamax tanker transport setup in a life cycle perspective indicates that the increased need for extra tonnage, when speed is lowered, will give a marginal effect on total greenhouse gases per transport work performed. This as the operational emissions connected to the consumption of fuel oil totally dominates the impact compared to building, maintaining and scrapping a vessel.

Ämnesord

SAMHÄLLSVETENSKAP  -- Ekonomi och näringsliv -- Företagsekonomi (hsv//swe)

SOCIAL SCIENCES  -- Economics and Business -- Business Administration (hsv//eng)

TEKNIK OCH TEKNOLOGIER  -- Samhällsbyggnadsteknik -- Transportteknik och logistik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Civil Engineering -- Transport Systems and Logistics (hsv//eng)

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