Session: 14-01-01 - New Concepts & Retrofit Solutions

Submission Number: 180169

Model-Based Evaluation of Alternative Energy Systems for Retrofit Decarbonization of Fishing Vessels 

This study evaluates decarbonisation strategies for existing fishing vessels through the design of alternative energy systems under realistic engineering constraints. Various technologies are evaluated, such as batteries, fuel cells and alternative fuels, with the baseline of marine gas oil (MGO).

The proposed methodology shows that while the sizing of power generation systems can be generalised, the sizing of fuel storage systems must be determined on a case-by-case basis. The approach first establishes the essential power requirements for propulsion and electrical loads to maintain an unchanged operational profile. This covers propulsive power and other loads dedicated to vessel operation, such as cranes and hotel services, but excludes power consumed solely by systems associated with the power-generation plant and the fuel storage and conditioning—often referred to as balance of plant and dependent on the fuel and power system type.

The following cases were examined:

·       Compressed hydrogen-powered fuel cells.

·       Methanol-powered main engine and generator sets.

·       Ammonia-powered main engine and generator sets.

·       Biodiesel-powered main engine and generator sets (Fatty Acid Methyl Ester – FAME was considered).

These were compared to the base case (as-built) marine gas oil-powered main engine and generator sets. A cod trawler has been selected as a representative retrofit case.

A combined top-down and bottom-up method was developed: essential propulsion and electrical demands were derived by subtracting the power consumed by all components involved in fuel distribution, conditioning and equipment directly linked to fuel, and power production from the total generated power. From the installed capacities of the main engine and auxiliary generators, the resulting propulsion and auxiliary loads—covering equipment such as pumps, cranes and hotel services—were used as the baseline for reverse-sizing each alternative fuel system, identifying the required equipment and accounting for differences in mechanical and electrical efficiency. Three operational scenarios—manoeuvring, seagoing and fishing—were examined using appropriate load factors for both propulsion and electrical demands. After determining system size and fuel consumption, fuel storage requirements were calculated using regulatory standards for tank placement, fuel preparation room (FPR) and tank-connection space (TCS), including cofferdams and insulation where applicable. Vessel arrangement drawings informed the feasibility and spatial integration of installations, after which fish storage layout and operational endurance (days at sea) were reassessed to preserve the original operating profile.

For biodiesel, configurations between two extremes were feasible: at one end, no reduction in operational endurance with up to a 35% reduction in fish storage volume; at the other, no loss of fish storage with a 44% decrease in endurance. Methanol results in an 82.5% reduction in operational endurance and a 57% loss of fish storage. Ammonia causes a 73.5% reduction in operational endurance and the same 57% reduction in fish storage. Hydrogen preserves fish storage entirely but leads to a 98.5% decrease in operational endurance. These findings indicate that, among the assessed low- and zero-emission fuels, only biodiesel presents a realistic retrofit option for fishing vessels without critically compromising operational viability or catch capacity.

Presenting Author: Spyridon Brouzas Norwegian University of Science and Technology

Presenting Author Biography: Having passed from shipping companies, a classification society, shipyards and one of the most renowned French marine design offices where he was part of the design of one of the first methanol dual fuel large container vessels retrofit, an FPSO newbuild and a novel WIG-type vessel, he decided to continue his journey in the marine world by investigating hydrogen-based energy systems to, hopefully, arrive at a disruptive solution that can revolutionise Green Shipping as part of his PhD.

Authors:

Spyridon Brouzas Norwegian University of Science and Technology
Mehdi Zadeh Norwegian University of Science and Technology
John Kokarakis Bureau Verittas
Rebecca Thorne The Institute of Transport Economics (TØI)
Ingrid Sundvor The Institute of Transport Economics (TØI)
Kenneth Løvold Rødseth The Institute of Transport Economics (TØI)