Disclosed is a ship propulsion system comprising an internal combustion engine for propelling a ship, the internal combustion engine comprising a combustion chamber for burning fossil fuel; the ship propulsion system further comprises an electrolysis chamber for producing hydrogen gas and oxygen gas, and a vacuum pump for sucking the hydrogen gas and the oxygen gas off the electrolysis chamber. The ship propulsion system also comprises a gasification tank in which volatile organic compounds, in particular methanol or ethanol, are gasified, and a supply line for delivering a gas mixture to the combustion chamber, said gas mixture comprising gasified organic compounds and at least some of the hydrogen gas and of the oxygen gas. The invention further relates to a corresponding method for operating a ship propulsion system.
