Energy efficiency analysis of a flexible marine hybrid propulsion system

The paper analyses some advantages of the hybrid ship propulsion, enhanced by the use of some energy recovery technologies. The concept design of a power plant for a Ro-Ro ferry is presented as a case study, since this particular ship can best take advantage of the operational flexibility of this propulsion type. As an element of innovation, the hybrid propulsion flexibility is analysed taking into account the installation onboard of dual fuel engines. This leads to examine the influence of natural gas, being rather different from traditional diesel oil in performance and price, on the propulsion system efficiency and fuel cost saving. Moreover, technical solutions as the waste heat recovery from the exhaust gas of the engine, equipped with innovative hybrid turbochargers, are also considered to produce additional electric energy, improving the overall efficiency of the vessel.