A methanol impact tool for yachts

Abstract

Superyachts are large emitters of greenhouse gases, as well as other emissions such as NO_x, SO_x and PM. In order to meet the climate goals set by the IMO, to reduce GHG emissions by 50% in 2050, alternative fuels are being investigated. Methanol is an alternative fuels with great potential. Methanol can be produced completely carbon neutral from biomass or captured CO₂, contains no sulphur, can be stored in liquid form at atmospheric pressure and temperature and can be used in both fuel cells and combustion engines. There are currently no yachts sailing on methanol but methanol has already been implemented in several other ships. Both yacht builders and owners show interest in the implementation of methanol. Since it is unclear which alternative fuel will become the standard on the long term in the yachting industry, it is of interest to also investigate the impact over a longer period of time or of several pathways. Previous research is limited to emissions and costs related to alternative fuels on a limited range of ship types which do not include yachts. The impact of methanol on the design, emissions and costs is still largely unknown for yachts. In order to determine this impact, the properties of methanol, rules & regulations regarding methanol, design impact of the storage of methanol, environmental impact of using methanol and the impact on costs are investigated. To determine this impact for several yachts, a tool has been developed which can be used from the early design stages. The tool uses the properties of a yacht to determine power and fuel volume requirements for the implementation of methanol. It also determines the available volume in the yacht for methanol storage in a basic tank arrangement. Together these form the properties of the yacht with the implementation of methanol. From these properties, the emissions and costs are determined and then combined in a pathway analysis to determine differences in impact of several future pathways. The results show that using methanol generally has a positive impact on emissions, compared to a diesel yacht. Methanol offers SO_x free emissions, a reduction of PM emissions and NO_x emissions equal to that of diesel without the necessity of after treatment. CO₂ emissions slightly increase with fossil methanol but can be net zero with renewable methanol. The impact of methanol on converter and storage costs is considered negligible compared to a diesel yacht. Fuel costs of fossil methanol are slightly higher than fossil diesel, renewable methanol fuel costs are lower than renewable diesel and 5 times higher than fossil methanol. The impact of methanol on the design is relatively large. Compared to diesel, approximately 2.3 times the amount of fuel is required for an equal range. The double bottom is not a feasible location for methanol tanks. A significant amount of interior area is occupied by the fuel tanks and the surrounding cofferdams. Therefore retrofitting existing yachts with methanol is not considered feasible. For new designs, methanol is considered a feasible option.