ENGINE SYSTEM AND METHOD OF OPERATING THE SAME

An engine system comprises a first fuel store of a first fuel, a second fuel store of a second fuel, an engine arranged to produce mechanical power by combustion or oxidation of fuel in the engine, a fuel distribution system arranged to deliver fuel from the first and second fuel stores to the engine, the first fuel delivered at a first flow rate, the second fuel delivered at a second flow rate, the first and second flow rates contributing to a total flow rate of fuel to the engine; and a control system arranged to control the relative fractions of the total flow rate of fuel to the engine represented by the first and second flow rates according to the required power output of the engine such that the relative fraction of the total flow rate of fuel to the engine represented by the second flow rate increases with increasing required power output of the engine for at least part of a period of operation of the engine, wherein the first and second fuels are selected such that operation of the engine using only the second fuel results in a lower engine temperature than operation of the engine using only the first fuel, when producing the same amount of mechanical power and/or wherein the second fuel has a lower specific energy than the first fuel and/or wherein the second fuel produces more water during combustion than the first fuel per unit of fuel energy released during combustion.