Fuel Minimization in Diesel-ElectricTugboat Considering Flywheel Energy Storage System

Energy storage system plays an important role in electric propelled marine vessels for efficient power management. This paper considers flywheel storage system in place of battery storage for reducing fuel consumption in a diesel-electric tugboat. To achieve fuel efficiency, optimal scheduling and controlling of energy sources and energy storage devices take place in consideration with tugboat load demand. A simple fuel optimization problem considering flywheel and battery storage system is formulated. Economic analysis is done in consideration of both the storage systems. Furthermore, DFIM as variable speed generation is considered in this research for tugboat power generation in the interest of better efficiency at part load operation. Fuel usage at fixed speed and variable speed diesel engine with flywheel and battery ESS are correlated. From the test results, it is observed that the adoption of 50kWh battery and 50kWh flywheel ESS offers 21.4% and 23% of fuel reduction in comparison with diesel-mechanical propelled tugboat. Whereas the adoption of variable speed operation of diesel generator with 50kWh flywheel offers 25.6% of fuel reduction.