The maritime sector represents about 13.5% of the total greenhouse gas (GHG) emissions at EU level (Source: EEA, 2020). In order to foster the decarbonisation of fuels in the maritime sector, the IMO fixed a target of 50% cut of GHG emissions up to 2050 and the manufacturing of zero-emission ships within 2100 (100% cut of GHG emissions with 2008 levels considered as baseline). The path towards decarbonisation of fuels in the maritime sector will also lead to the reduction and/or abatement of pollutants like CO, NOX, SOX, PM, BC, HC that are emitted by fossil fuels combustion (mainly HFO, GDO and LPG, that feed engines for propulsion, generators used as auxiliary power units and boilers). The EC already cofunded projects aiming at the decarbonisation of large ships and commercial cargos that contribute most to GHG emissions (representing a share of about 70%). The down-scaling application on superyachts (40m+) and yachts (< 40 m) can be of interest, considering their average operational profile that see them spending most of the time (about 82%) anchored or berthed, conditions that do not require the operation of the main engines for propulsion. The installation of a methanol reformer coupled to a PEM fuel cell (mFC system) could represent an interesting solution as auxiliary power unit of yachts and superyachts, to cover the hotel load but also to sustain slow speed cruising and manoeuvring operations in ports (the latter if combined with hybrid propulsion). Aim of the LIFE OCEAN project is to substitute the traditional diesel generators used to cover the hotel loads of a Sanlorenzo superyacht with a 60 kWe mFC system. Along with air pollution mitigation, on board noise will be abated while underwater noise will be reduced thanks to the elimination of diesel generators. The solution adopted constitutes a zero-carbon technology for the maritime sector, adopting green methanol whose large capacity production is growing at both EU and extra-EU level.