Abstract: This study investigated the possibility of using a stirling engine generator to reduce the fuel consumption onboard a tanker ship. It is intended to function as a waste heat recovery unit fitted in the exhaust gas line of the main propulsion diesel engine and is to operate by means of recovering waste heat energy from the exhaust gas and converting it to mechanical work to drive an electric generator. The electric power generated will be supplied to the ship’s main switchboard to help supplement the electric power requirement onboard. Since the energy input to the Stirling engine will be from waste heat, it is expected to cause a reduction in fuel consumption for electric power generation without the adverse effects of an increased carbon footprint and greenhouse gas emissions. Using data from a 157209 gross tonnage tanker ship, an estimation of power which could be produced by the Stirling engine generator from the exhaust gas of the 25090 kW two-stroke main propulsion diesel engine at full speed condition has been calculated. Expected reduction of the ship’s fuel consumption has also been presented.