Exhaust Gas Cleaning Systems - Selecting the Best EGCS Option Using the Analytic Hierarchy Process and the Cost Benefit Analysis
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- Institutt for marin teknikk 
The objective of this master thesis is to investigate whether an exhaust gas cleaning system (EGCS) installation could be profitable on board three of BW Fleet Management AS vessels. If so, which EGCS will be the best option for each vessel. An Analytic Hierarchy Process (AHP) has been carried out to investigate which EGCS solution will be best for the case vessels, with a main focus on technical aspects. To investigate whether an EGCS installation is profitable compared to changing to marine gas oil (MGO), and which of the EGCS solutions that will be the most profitable, a Cost Benefit Analysis (CBA) has been conducted. The thesis looks at wet hybrid EGCSs, which uses seawater directly from the sea in open loop mode and freshwater with an alkali additive in closed loop mode to clean the exhaust gas. Five different EGCS solutions from four manufacturers have been looked at for potential installations on board BW vessels. They include the solutions from Wärtsilä (both I-SOx and V-SOx solutions), PureteQ (Inline solution), Alfa Laval (U-design solution) and Clean Marine (cyclone solution). These EGCS solutions have been investigated for possible installation on board a VLGC, a LR1 and a bulk carrier. The structural design of the vessel is important when considering which solution will be the easiest to install on board. The scrubber tower is the biggest component of the system, and influences the structural feasibility the most, as it must be located after the exhaust outlet of the main engine. For the VLGC the Wärtsilä I-SOx and the PureteQ towers most likely can be installed inside of the funnel casing, which is evaluated as preferrable. The towers in the three other solutions will have to be installed on top of a platform astern of the casing as the footprint of the towers are too big. For both the LR1 and the bulk carrier, none of the EGCS towers could be installed inside of the funnel casing and must therefore be installed on either the starboard or port side of their funnel casing. The installation of an EGCS can impact a number of the existing systems on board the vessels, which may affect the total the power demand of the vessel and the total back pressure to the engine. However, the case vessels seem to have sufficient power capacity to handle the increase in power demand, and the back pressure caused by the solutions to the engine will most likely not exceed the maximum acceptable back pressure limit of the engines. In the AHP, the EGCS solutions are evaluated based on a set of six defined technically focused criteria, with the aim of finding the best EGCS solution for each case vessel. The Clean Marine solution is found to be the clearly best solution for both the LR1 and bulk carrier, whereas for the VLGC the PureteQ solution is found to be the best, marginally better than the Clean Marine solution. In the CBA, the benefit of the EGCSs is defined for the vessels to become compliant with new regulations. The price difference between MGO and HFO is used to find the benefit of the EGCS solutions, which was approximated to be 43.1 million USD for both the VLGC and the bulk carrier, and 37.8 million USD for the LR1. The cost estimation was calculateds giving values both for the CAPEX and the OPEX of the different solutions for each vessel. The total cost of the solutions were less than 11.5, 12.3 and 9.5 million USD for the VLGC, the LR1 and the bulk carrier, respectively. These results give cost benefit ratios that are greater than 1, which implies that all EGCS solutions will be profitable to install on board each case vessel. The net present values show that there are relatively small differences between the total savings of the solutions for all three case vessels. The NPVs also show that the break even points are within BW s requirement of 5 years. The thesis concludes that retrofitting EGCS on board the VLGC, the LR1 and the bulk carrier seems to be profitable. The cost estimations, and especially the CAPEX, are exposed to major uncertainties, which can impact on the CBA results. The results of the AHP are believed to be more robust. The main determining factors when selecting an EGCS solution for a vessel seems to be how the structural feasibility, the power consumption and the additional back pressure of the solutions affect the vessel. This is why the Clean Marine EGCS solution comes out as the most favourable solution from a technical point of view. For further investigation of the topic, it is recommended to focus on the main uncertainties affecting the results of the thesis, especially to clarify the CAPEX assumptions and the actual operational lifetime of the solutions, where the type of materials used and the extent of maintenance needed are the most important uncertainties. In addition, a more thorough structural feasibility study must be carried out, investigating the installation of the solutions in more detail. Future rules and regulations should also be considered, to evaluate the risk of further consequences that needs to be addressed.