Among the renewable fuels, methanol is particularly well suited for marine propulsion systems as it is easier to handle in terms of fuel storage, global availability, safety requirements, retrofit solutions and emissions compared to other sustainable fuels. The objective of this presentation is to provide an overview of the use of methanol as a fuel for internal combustion engines in marine propulsion systems, with a focus on the advantages and disadvantages of the methanol combustion process. This will be achieved by comparing two different diesel-methanol combustion concepts with a state-of-the-art diesel engine. In addition, the efficiency chain of the methanol production and the requirements for the exhaust gas aftertreatment system will be discussed.