Due to more stringent greenhouse gas (GHG) emission regulations in the maritime industry, solutions are being sought to decrease the GHG emissions of crew transfer vessels used in offshore wind farms. Multiple alternative fuels and power generating systems can be used to decrease these emissions. In this research, a comparative study is performed on six concept solutions. Four fuel types (hydrogen, HVO, methanol, and renewable energy) and three different power generating system components (proton exchange membrane fuel cells, lithiumion batteries, and internal combustion engines) are considered. The option of charging a battery-powered ship offshore is also considered. The goal of this research is to identify the most cost-effective system to reduce GHG emissions. The comparison is based on the total cost of ownership, the GHG emissions of fuel production and utilisation, and the GHG emissions of the production of the power generating system. In order to achieve this, the component sizes and lifetimes are calculated based on the constraints of the ship and the operational profile with different transit distances to the wind farm. The lifetime of the fuel cell is based on a cell voltage degradation model developed in this research. A battery electric ship with a methanol genset is found to be the best method with the largest GHG emissions reductions in relation to cost. Without charging offshore for a transit distance up to 18 km, and with offshore charging beyond 18 km. If charging offshore is not considered viable, a combustion engine with hydrogen is the best option for a transit distance of 18 km up to 68 km, and HVO upwards of 68 km.