The International Maritime Organization (IMO) aims to achieve net-zero greenhouse gas (GHG) emissions by 2050. While newbuilding vessels are an important piece of the puzzle, retrofitting existing ships to operate on alternative fuels will also play a significant role in reducing GHG emissions,2 especially considering the IMO’s current ambitions.

Bulk carriers account for 14% of the global merchant vessel fleet, with medium-sized vessels (60,000-99,000 DWT) comprising approximately 28% of the bulk carrier fleet. The Kamsarmax vessel is one of the largest vessels within this medium-sized category. In 2018, this category was responsible for about 63 million tonnes of GHG emissions , representing 6% of total fleet emissions. Medium-sized bulk carriers, specifically Kamsarmax vessels, are also identified as a significant source of GHG emissions in the IMO’s Fourth GHG Study.

According to Clarksons Research,4 the Kamsarmax fleet has an average age of 10.3 years, compared to around 12 years for bulk carriers overall. Furthermore, 99.8% of the existing fleet consists of conventional single-fueled vessels, while for newbuilding vessels, 94.8% will be conventionally fueled.

Figure 2 shows the different options that owners can consider when decarbonizing bulk carriers. It is important to recognize that bulk carriers predominantly operate within the tramp sector. Most of these vessels do not operate according to a set schedule and are expected to operate globally, calling at different ports worldwide. In the future, bulk carrier operators will face the dual challenge of operating in a multi-fuel reality, while finding green fuels that will enable them to meet decarbonization targets.

Most bulk carrier vessels currently in service are powered by conventional fuel.3 Efforts to decarbonize these existing vessels will require consideration of options such as drop-in biofuels or retrofitting vessels to enable the use of alternative fuels. This study focuses on the latter option, specifically retrofitting for methanol capability.

Overview of this report

This report presents a technical and economic study of an existing bulk carrier, examining the major design considerations for retrofits and demonstrating technical feasibility. It serves as a case study for shipyards and designers interested in methanol retrofit designs, offering practical examples of challenges and solutions. Additionally, it provides insights for shipowners and operators on the operational aspects of retrofit projects, including integration beyond the conceptual phase. Below is a brief overview of the main sections of this report.

Section 3 describes the general design objectives and requirements for this study. These include endurance requirements, vessel particulars, and methanol fuel hazards.

Section 4 examines various tank arrangements to find the most optimal in terms of volume, endurance, and technical acceptance (structural and stability criteria). Design reviews identified the most suitable arrangement for the purposes of this study, considering cargo capacity loss, potential operational restrictions, and compliance with vessel rule requirements.

Section 5 assesses the installation approach for the methanol storage tank, focusing on yard handling capability and coating requirements. It also examines the conversion time required.
Section 6 shares the results of a thorough HAZID review, which assessed hazards and mitigation actions. The final design received Approval in Principle (AiP) from ClassNK, confirming its robustness and safety compliance. A retrofit design package has been developed, based on a representative Kamsarmax design, with widespread applicability across the fleet. This approach has the potential to accelerate the fleet’s transition to low-emission alternative fuels.

Finally, Section 7 presents the results of an economic analysis regarding the overall opportunities and challenges of retrofitting an existing asset for methanol capability.
Source: Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping