Electrical Load Distribution and its Impact on Annual Fuel Consumption
To facilitate the development of technologies for improving the fuel efficiency ships, a study was performed to quantify the annual fuel consumption associated with each of the major electrical loads. For a test system, a 100 m class passenger vessel was selected. While different ships may have somewhat different distributions, this particular choice has the richness of applications to make it an interesting example for analysis.
As a first step in the analysis, power distributions associated with various vessel operating modes were compiled. By combining these load distributions with an assumed annual percentage of time spent in each mode, a relative account of the fuel consumption for key electrical loads was produced. The figure shows the results of this analysis. While this was done for a hypothetical ship, a similar assessment can be made for an operating ship for which operational data are available.
Discussion of Results
Since the energy and power for the entire ship's electrical load is produced from diesel generator sets, each electrical load has a direct impact on the fuel economy of the overall system. As shown in the figure above, these electrical loads can be broken down into the following categories: propulsion loads, winch loads, thruster loads, HVAC, clean power M-G set, cooling plant loads, 230V and 120V feeder, distribution board, and other miscellaneous loads.