ECONOMICS AND ENVIRONMENTAL IMPACT OF SHIP SPEED REDUCTION FOR AFRAMAX TANKERS

Transcription

1 Alan Klanac, as2con-alveus, Rijeka/Croatia, Petar Nikolić, as2con-alveus Rijeka/Croatia & Faculty of engineering, University of Rijeka, Rijeka/Croatia, Maja Kovač, as2con-alveus, Rijeka/Croatia & Faculty of engineering, University of Rijeka, Rijeka/Croatia, Jon McGregor, Bureau Veritas, Neuilly-sur-Seine Cdx/France, ECONOMICS AND ENVIRONMENTAL IMPACT OF SHIP SPEED REDUCTION FOR AFRAMAX TANKERS Summary In this study we analyse the economic effects and environmental impact of speed reduction for an AFRAMax tanker. By varying the speed and the installed power, considering also the effects of fuel consumption difference, market conditions and the increase in transportation time, we show that slow steaming can be simultaneously economically sound and eco-friendly. Changes in the environmental efficiency design index, or EEDI, are also addressed. Key words: speed reduction, ship emissions, CO 2, charter rate, AFRAMax, tanker, EEDI UTJECAJ SMANJENJA BRZINE AFRAMAX TANKERA NA PROFITABILNOST BRODA I OČUVANJE OKOLIŠA Sažetak Za AFRAMax tanker provedena je analiza utjecaja smanjenja brzine na ekonomsku isplativost broda i utjecaj na okoliš očuvanje okoliša. Izradili smo ekonomski model. Simuliranjem smanjenja brzine te promjenom instalirane snage motora, uočene razlike u potrošnji goriva te promjene u režimu plovidbe rezultirale su potvrdom naših očekivanja. Promijene u indeksu energetske efikasnosti (EEDI) u su također provjerene. Ključne riječi: smanjenje brzine, ispušni plinovi, CO 2, cijena najma broda, AFRAMax, tanker, EEDI

2 A. Klanac, P. Nikolić, Economics and envrinomental 1. Introduction Ship emissions participate in the global CO 2 emissions with 3.3%, SO x are emitted at about 4% of world total, while NO x are about 7% of total emissions. According to the European Union targets [1], these emission levels need to be drastically reduced already in Knowing that the installed power on a ship, and thus the emissions have an exponential relationship with the speed, by significantly decreasing this speed we can greatly reduce the emissions. Furthermore, reducing the speed will also significantly reduce the fuel consumption and thus the operating costs. History shows that reducing service speed of ships has been a common strategy when charter rates were low and/or the fuel oil prices were high. This can be also noticed in the present time [2,3]. In this paper we provide first principle analysis of effects of slow steaming to ship. We analyse how and why a slow steaming ship can be economically sound, and how does this reflects onto direct ship stakeholders, i.e. shipowners and charterers. For this, a simple, but generally applicable economic model is established. All calculations presented in this paper are made for the AFRAMax tanker with the following particulars is taken into consideration: Table 1. Main particulars of the AFRAMax L OA : 259 m B : 47 m DWT : t V : 15 kn Main engine : Wärtsilä RT flex84t D Main engine MCR: kw Fuel consumption 58.9 t/day CO 2 emissions: t/day *assumed as 6% of a total exhaust weight The paper is divided into four parts. The first part (Ch. 2.1) deals with the general information concerning the calculations and problem definition. This part argues assumptions, and all the relevant data are explained there. The second part (Ch. 2.2) of the paper concerns calculation of overall profitability of slow steaming ships. In the third part (Ch. 3), the environmental impact is discussed. 2. The economics 2.1. Problem definition The analysis of benefit of slow steaming on at the ship level is based on the comparison of profitability between the ship operating at the standard and at slow speeds on the annual basis. Relative benefit B of the slow steaming ship at service speed V is calculated for the shipowner and charterer respectively, using the following equations: (1)

3 Economics and envrinomental A. Klanac, P. Nikolić where N SS is the number of slow steaming ships necessary to transport the equal amount of cargo as a ship operating at the standard speed, calculated as a ratio N SS (V) = V /V. ACR is the annual charter rate, defined according to the: where t is percentage of commercial use of ship per annum (taken as a percentage of annual ship exploitation, and was assumed that its value is 0.9, while DCR is daily charter rate. C O are shipowners operating cost per ship, estimated at 2.5 mil. USD annually. These involve e.g. the annual crew cost, maintenance, insurance, etc. and are assumed not to be affected by the speed reduction. C FO are the fuel cost In order to determine the fuel oil costs as a function of the ship s service speed, we select different engines for the AFRAMax slow steaming at 12.5, 10, 7.5 and 5 kn. Table 2 lists these engines and their characteristics. This provides sufficient amount of points through which a polynomial can be fitted, approximating with sufficient accuracy sought functional relationship. The following global market prices for fuel are applied. Heavy fuel oil, for the slow speed engines, is taken at 370 USD/t, while the diesel oil for the medium-speed engines is taken at 470 USD/t. These are average value for the year 2009 [4] Discussing the benefits of slow steaming on the ship level can not provide the overall economic argumentation. Profitability of slow steaming should be compared considering the same amount of cargo per unit time. Thus, we build an economic model that encompasses the main stakeholders affecting on the ship service speed, the ship owner and charterer. Following the assumption of the economic equilibrium in which stakeholders will, tend to equally share the benefits of an economic behaviour as much as possible, it is possible to determine the optimal service speed that produces equal amount of benefits for the stakeholder for a given market condition. This will then allow us to study the effects of speed reduction onto profitability of the stakeholders. AFRAMax tanker, as a case ship is assumed to be in the time charter, for this analysis, and in a long-term contract with the charterer. The influence of duration of the journey between the slow steaming ship and the ship operating with standard speed can be therefore neglected. Furthermore, the additional investments, necessary to acquire the additional slow steaming ships to compensate for the lost transport capacity in time unit, can also be neglected. This assumption somewhat simplifies the analysis. In the time charter contract, shipowner needs to cover the operating costs i.e. the crew costs, maintenance and repairs etc., and charterer directs the commercial operations of the ship and pays all voyage expenses, i.e. bunkers, port charges and canal dues, and cargo handling costs [5]. Calculations are made in accordance with today s market prices, i.e. fuel oil prices, harbour fees, insurance fees, crew cost, etc., and varying charter rates for time charter. We did not consider other systems on board. (2) (3)

4 A. Klanac, P. Nikolić, Economics and envrinomental Fig 1 Speed - power curve for selected ship Table 2. Comparison of ships speed with power, consumption and annual cost of fuel DESIGN SPEED (kn) P E (kw) TYPE Wärtsilä RT-flex 84T D [6] MCR (kw) FO (t/day) FO COST (USD/day)* CO 2 (t/day) Wärtsilä 38 8L38 [7] Wärtsilä 26 8L26 [8] Wärtsilä 20 8L20 [9] Wärtsilä 20 4L20 [9] *assuming 90% annual exploitation Fig. 2 Mutual dependence between ships speed and fuel oil annual cost, AFRAMax tanker Because the slow steaming ship will conduct fewer journeys per annum, we can expect that the costs of port calls will be linearly smaller than for the ship operating at the standard

5 Economics and envrinomental A. Klanac, P. Nikolić speed. This means that for the comparison on a fleet level, the harbour costs would remain the same annually, and can be thus omitted from the analysis. We also omit from the analysis the differing costs for engine installation at slow and standard speeds, as well as the benefits which might occur with the reduced requirements amount space needed for engine room once the demand for power reduces The analysis and discussion Having defined now all the elements of the benefit equations (1) and (2), we are ready to determine whether slow steaming is economically sound. Following the assumption of equity between the stakeholders, and thus of their benefits, we can equate them, so that it is valid: This way we can determine the stakeholder benefit for a reduced speed V in comparison to the operation at the standard speed. Given that the fuel costs are expressed as a cubic equation of speed, see Eq. (3), we solve this problem graphically. Supposing the value of a daily charter rate, we determine the speed for which the condition of Eq. (3) holds. If we plot now the values of benefits against the speed, and the supposed values of daily charter rates also against the speed we attain the following two graphs; see Figures 3 and 4. (4) Fig. 3. The value of equal benefit from slow steaming for the shipowner and charterer as the function of speed In Figure 3, we can see that both shipowner and charterer will enjoy a joint benefit. If the ship speed is reduced between 5 and 15 kn, outside this area of speeds, we can not expect joint benefits in comparison with the ship operating at standard speed. The maximal equal benefit for the shipowner and the charterer is USD at attained 9.5 knots. This shows that the slow steaming for an AFRAMax tanker in the wide range of speeds is an economically sound strategy

6 A. Klanac, P. Nikolić, Economics and envrinomental Fig. 4. Expected daily charter rate in dependence to ships service speed, AFRAMax tanker, for equal benefit of slow steaming (dotted line is supposed, based on continuity of the economic model) Fig. 4. shows the daily charter rates values that correspond with the equal benefit for stakeholders for the given speed. Since the curve is obtained relative to the standard service speed of 15 kn, there is a discontinuity visible there. To test attained curve, let us mark now the service speed of 9.5 knots, which incurs the biggest equal benefit of slow steaming. In this case the daily charter rate for AFRAMax tanker should be USD. Considering the benefit of both stakeholders, this value is sensible as it assures lower costs for the charterer for the lower costs of fuel. The benefit for the owner is in the increased business with about 50% more ships employed. Considering the assumption that the benefits to the stakeholders are equal, we can assume that the attained daily charter rate represents effectively a stable charter rate for the give speed of operations. Thus, we venture into interpolating between the two parts of the attained curve that are discounted at 15 kn. The validity of this argumentation can be found if we plot some available figures of average speed and daily charter rates for AFRAMax from the literature. Thus according to the long term record of AFRAMax tankers, attained from AIS data [10], their average service speed is 12,6 kn. The average daily charter rate is USD, according to Marine news [11]. Our prediction that for 12.6 knots service speed, daily charter rate should be USD, and that for daily charter rate of USD, service speed should be 11.8 knots. This is the question that should further be investigated in the future. Furthermore, charts in Figures 3 and 4 effectively prove that the slow steaming is a sound strategy. This is especially valid in the times of weak economic growth, with low charter rates, the benefits for both stakeholders are positive. Operation with speeds higher than standard is, on the other hand, irrational, even if the market would be strong with high daily charter rates.

7 Economics and envrinomental A. Klanac, P. Nikolić 3. Environmental impact 3.1. First principles Besides the positive economic impact, slow steaming due to the reduced emission can be a viable option for eco-shipping. As mentioned, by reducing the engine size, we reduce the emissions, and thus the CO 2, NOx and SOx gasses. Following up on Table 2, we can determine the percentage of CO 2 emissions cut per ship in comparison with the ship operating at standard speed. Given the CO 2 on the emissions data obtained from the manufacturer, seen in Table 2, AFRAMax slow steaming results in a significant positive ecological impact. Based on this data, we can construct the diagram in Figure 5. We came to formula which best describes how much of CO 2 exhaust is reduced, as a function of ships speed. Figure 5. Annual CO 2 exhaust reduction in tonnes, function of ships service speed and adjusted to fit the same cargo capacity per unit time As it can be seen from Figure 5, if we reduce ship service speed just by one third, to 10 knots, CO 2 emission reduction will be more than 80% of todays. If we reduce speed to 5 knots, the amount of reduction will be more than 95% EEDI IMO recently initiated implementation of the EEDI (energy efficiency design index) [14], to be conceived as a future mandatory newbuilding standard. EEDI for a ship represents the basic energy efficiency of a design. The fundamental principle is that the emission index expresses the ratio between the amount of emission and the benefit that is generated, expressed as a transport work capacity. The EEDI is defined for a ship under specified conditions (e.g., engine load, draught, wind, waves, etc.) in relation to the nominal transport work rate. The unit for EEDI is grams of CO 2 per capacity-mile, where capacity is an expression of the cargo-carrying capacity relevant to the cargo that the ship is designed to carry. It is applied here to capture more holistic aspect of ship speed reduction. In Table 3. we can see EEDI comparison for different speeds for the AFRAMax tanker taken into consideration. Table 3. EEDI for different AFRAMax speed's and adjusted for equal amount of cargo transported

8 A. Klanac, P. Nikolić, Economics and envrinomental SPEED [kn] EEDI [g CO 2 /t nm] EEDI* [g CO 2 /t nm] adjusted for the same transport capacity per unit time It is not a surprise that the slow steaming AFRAMax has a smaller EEDI and also the slower the better. However, if adjusted for the same transport capacity pre unit time, the EEDI is minimal for the ship operating at 12.5 kn. This means that on the fleet level addition of more ships make up for the lost capacity will reduce the efficiency of the system. Nevertheless, the ecological efficiency will be still better than for a ship operating at standard speed. 4. Conclusion The purpose of this paper was to investigate whether it is economically sound to reduce the speed of ships. In these investigations we have considered a typical AFRAMax tanker. The findings indicate that with the growing fuel prices and with the growing requirement for the ecological protection, we can expect concept of growing slow steaming ships to become a viable option. But, as this affects in a way the logistic and supply chain, a change cannot be abrupt. Furthermore, a slow ship should require to have additional power available for assure to manoeuvre in rough weather conditions. This should be investigated more in the future. In principle the findings suggest that slow steaming is a sound strategy, but more work is to be done to prove it. REFERENCES [1] 2 ND IMO GHG study, London, 2009 [2] [3] [4] [5] Stopford, M., Maritime economics, 3 rd edition, Routledge, Oxon, 2009 [6] SULZER RTA-T, Engine selection and project manual, May 2009., [7] Wärtsilä 38, Project guide, Trieste, November [8] [Wärtsilä 26, Project guide, Trieste, June [9] [Wärtsilä 20, Project guide, Vaasa, September [10] [11] [12] Speed/Propulsion-Trends-in-Tankers.html [13] [14] Interim guidelines on the method of calculation of the energy efficiency design index for new ships, IMO, August, 2009.