Emission and Fuel Reductions for Offshore Support Vessels through Hybrid Technologies

Abstract

Traditionally offshore support vessels have been designed to ensure that they can perform their duties at nearly any sea state. This has been achieved through multiple engines and advanced dynamic positioning systems. This in combination with high safety standards set by the oil companies has resulted in a general operational pattern with vessels running multiple engines at low to medium loads to be prepared for unexpected incidents to happen at any time. At medium to high power the combustion engine produces each kWh with the lowest fuel consumption and the lowest emissions. When engines operate at low power, fuel consumption per kWh produced increases. For the cost of the operation, this increase in specific fuel consumption at lower loads makes a small impact compared to the total cost of the operation, while for emissions low loads implies that emissions of exhaust gases such as nitrogen oxides (NOx) and aerosols such as black carbon (BC) increases rapidly due to less favorable combustion conditions. This study investigates potential emission and fuel consumption reductions which can be achieved by introduction of hybrid technologies including their climate mitigation potential. In this context hybrid means engines of different sizes, battery storage of energy to take peak power requirements, and power management systems with a more balanced focus on reducing emissions and energy consumption while maintaining a high safety standard. Our results indicate that hybrid technologies reduce both emissions and fuel consumption and that the climate impact of the emission reduction is much larger than the impact due to the reduction in fuel consumption alone.