With increasing fuel prices and environmental awareness, maximizing energy efficiency is one of the highest priorities in voyage planning. Various weather routing algorithms have shown great potential in optimizing main engine fuel consumption while ensuring safe navigation. However, quantifying the fuel savings achieved by using these services remains a major challenge in the marine industry. The lack of a transparent and logical benchmarking system for comparing fuel consumption with and without engaging a fuel optimization service is the main roadblock in calculating fuel savings.
The optimization objective of the weather routing and dynamic speed algorithms is to find a route and speed schedule that achieves minimum fuel consumption by reducing adverse weather exposure. A route and speed schedule with favourable weather helps in achieving the target ETA at a lower engine RPM and thereby lower total fuel consumption. While theoretically these weather routing and speed scheduling algorithms show great promise in optimizing main engine fuel consumption for a passage, quantifying the actual savings achieved by engaging such a service remains a challenging task. Given the large number of variables including weather, Charter Party terms, berthing prospects and current vessel condition, it is impossible to find a past identical voyage as a basis of comparison of main engine fuel consumption.
A seemingly logical and transparent solution for estimating the benchmark fuel consumption is simulating the voyage in hindcast weather on a standard navigational route as per Charter-Party terms. However, this method is very sensitive to inaccuracy in the vessel hydrodynamic model used for simulation. For example, if the model always overestimates fuel consumption by 5%, then it may report savings of 5% even in voyages in which no weather routing/speed scheduling is applied. Moreover, it is important to simulate the voyage such that it achieves the same arrival time as the actual voyage so that the savings reported are not due to slow steaming but because of intelligent weather routing and speed scheduling.
The process of benchmark voyage re-construction is as follows:
Finally the fuel savings is = ME Consumption in the reconstructed benchmark voyage - Actual ME consumption in the voyage