Approaches to Economic Energy Management in Diesel-Electric Marine Vessels

Recently, the efficiency of diesel-electric marine vessels has been subject for discussion with focus on improving fuel efficiency, reducing the environmental footprint from emissions, as well as reducing running hours and maintenance costs. This paper presents an analysis of load profiles extracted from three different vessels during operation: 1) a ferry; 2) a platform supply vessel; and 3) a seismic survey vessel. The analysis of the extracted data shows that the loadings of the diesel engines are typically quite low, and do not fall within the optimal loading range of diesel engines' specific fuel oil consumption curves. Furthermore, three different power plant configurations are proposed and compared, which include fixed-speed (diesel engine generators) and variable-speed gensets and the implementation of an energy storage system. Moreover, energy management system (EMS) algorithms based on mixed-integer linear programming (MILP) are proposed as a suitable strategy for optimal unit commitment in the power generation. The results yielded from the MILP algorithms are compared with those from the EMS algorithms based on logic such as if/ else statements. The results indicate that optimal EMS algorithms in combination with a revised vessel configuration can increase the operational efficiency, in terms of fuel savings and reduction in genset running hours.