a marine engine comprising a combustion chamber configured for burning heavy fuel oil;

a turbocharger comprising a compressor with an air inlet and a compressed air outlet, a turbine, and a shaft coupled to the compressor and the turbine, the turbine provided in an exhaust path of exhaust gases from the marine engine such that the turbine rotates the shaft which in turn rotates the compressor;

a separation unit comprising one or more membranes that are structurally configured to concentrate nitrogen from a separator feed stream feed to generate a nitrogen-enriched air stream and a nitrogen-depleted air stream;

an air valve positioned in a flow path exiting the compressor, wherein the air valve is variably positionable to split flow between an intake air stream and a recovered air stream;

a mixing chamber with an inlet in communication with the separation unit to receive the nitrogen-enriched air stream and an inlet in communication with the air valve to receive the intake air stream and an outlet in communication with the combustion chamber of the marine engine for providing a nitrogen-enriched intake air stream to the combustion chamber, wherein the nitrogen-enriched intake air stream is formed from a combination of the nitrogen-enriched air stream and the intake air stream;

an air operated compressor positioned in a recovery flow path connecting the air valve and the separation unit to receive the recovered air stream and generate a separator feed stream, the air operated compressor configured to increase the pressure of the recovered air stream with air drawn off from the recovered air stream driving the air operated compressor; and

an air flow controller communicatively coupled to the air valve, the air flow controller comprising a processor and a computer readable and executable instruction set, which when executed, causes the processor to:

direct the air valve to adjust to the determined valve position.