Energy and exergy analysis of the turbo-generators and steam turbine for the main feed water pump drive on LNG carrier

•Two low-power steam turbines in the LNG carrier propulsion plant were investigated.•Energy and exergy efficiencies of both steam turbines vary between 46% and 62%.•The ambient temperature has a low impact on exergy efficiency of analyzed turbines.•The maximum efficiencies area of both turbines was investigated.•A method for increasing the turbo-generator efficiencies by 1–3% is presented.