Fuel Cell Technologies and Applications for Deep-Sea Shipping

Whereas internal combustion engines convert chemical energy through combustion into mechanical motion, fuel cells convert chemical energy through electrochemical reactions into electricity. While the designs of fuel cells are comparable to those of batteries, the former use a flow of fuel and oxygen to supply a continuous production of electricity as long as fuel is supplied to the system. A fuel cell generally consists of two electrodes (anode and cathode) and an electrolyte. As fuel and oxygen are supplied to the system, a voltage is triggered by the chemical reaction at the contact between fuel and the anode. This generates direct current electricity that can be used for different applications, along with an outflow of heat and water. Several fuel cell technologies exist or are being developed, each focusing on a different combination of materials and fuels. While some of these technologies are common in other industrial applications, shipping applications are still limited. For example, fuel cells’ applications in the space industry date back to the 1960s, when a range of different technologies were deployed across different programs. More recently, fuel cells have been successfully used on land for material-handling applications and back-up power generation. By contrast, the first type approval for a marine fuel cell was only issued in 2022.

Notwithstanding the wide variety of fuel cell technologies, their common benefit is efficient conversion of chemical energy to electricity, compared to combustion-based processes. Fuel cells can additionally provide a reduction of certain emissions, such as nitrogen oxides (NO_X), sulfur oxides (SO_X), nitrous oxide (N₂O), and particulate matter. Furthermore, certain types of fuel cells could enable their users to work with a wide range of alternative fuels. Lastly, fuel cell systems have fewer moving parts than internal combustion engines, which will likely simplify design and maintenance.

The project was a collaboration between the Mærsk Mc-Kinney Møller Center for Zero Carbon Shipping (MMMCZCS) and our strategic partners and mission ambassadors: Stolt Tankers, Mitsubishi Heavy Industries, Tsuneishi Shipbuilding, Siemens Energy, Seaspan Corporation, ABB, American Bureau of Shipping, Royal Caribbean Group, Maersk, NYK Line, TotalEnergies, and Alfa Laval. Further, we thank the following technology suppliers, who supported this project and provided input on the report: AFC Energy, Ballard Power Systems, Bloom Energy, Corvus Energy, Elcogen, Freudenberg, PowerCell Group, and RIX Industries.

Given the inherent differences between fuel cells and internal combustion engines, it appears unrealistic to assume that fuel cells will compete with or entirely replace onboard internal combustion engines in the near future, even as fuel cells reach a high technological maturity level. This is due to the high initial costs currently associated with these technologies, along with the adjustments that would be required in ships’ engine-room design and standard operating procedures for the crew.

Rather, it seems more likely that different technologies will co-exist for the foreseeable future. Ship owners could combine fuel cells and internal combustion engines in order to leverage the advantages of each system. In this way, the industry could make the most of fuel cells’ environmental performance while also becoming more familiar with fuel cells and progressively scaling up investments as the technology becomes more affordable.

For this reason, our investigation focused on assessing the role that fuel cells could play in auxiliary load on board ships, rather than on propulsion. We believe that auxiliary power generation represents a good starting point for phase-in of fuel cell technologies, given the lower maximum loads and resulting costs of gensets compared to main engines. Auxiliary power is traditionally generated via four-stroke engines, which are slightly less efficient than the two-stroke engines typically employed for propulsion. As a result, vessels might operate on a combination of two-stroke engines (propulsion) and fuel cells (auxiliary load). This approach could help ship owners to make the most of existing technologies while phasing in fuel cells and, in turn, potentially lower vessels’ emissions.

To assess the feasibility of such configurations on deep-sea ships, we started by mapping the fuel cell technologies that are currently being developed for maritime applications. This was possible thanks to close cooperation with some of the technology suppliers who are focusing on this space. Information shared by suppliers consisted of performance data, initial cost estimates, and rough installation guidelines, including equipment size and interfaces with other ship systems. Once we gathered a sufficient level of detail from suppliers across various fuel cell technologies, we shortlisted the fuel cell technologies to focus on for this report, based on their technological readiness and the detail of the data made available.

Our main investigation centered on a desktop study examining the potential for fuel cells’ integration on board deep-sea vessels. We chose to focus on the ship segments responsible for the largest bulk of shipping emissions, i.e., bulk carrier, tanker, and container ship. Within these segments, we used real-world operational data shared by the MMMCZCS’s partner organizations to establish realistic operational profiles for one specific ship type in each segment. Building on this insight, we estimated the impact of fuel cells from several angles, aiming to capture information about their potential environmental performance along with the financial and business implications. Specifically, we analyzed the likely impact of fuel cell integration on energy efficiency, greenhouse gas emissions, fuel and equipment costs, and ship design for selected combinations of ship types, fuels, and fuel cell technologies from 2025 to 2040.

The results of this analysis show that, under the assumptions of our study, fuel cells could reduce both onboard fuel demand and the resulting greenhouse gas emissions. Further, these new technologies do not appear to require design modifications that would affect ship operations or costs beyond what can be expected for the combination of alternative fuels and internal combustion engines. However, our results also indicate that, on top of the high costs currently forecast for alternative fuels – which appear hard to compare to conventional fuels in the absence of a carbon tax – the additional cost premium of fuel cells affects their competitiveness in the short and medium term. If we focus on the long-term forecasts, the financial outlook for fuel cells improves but remains conditional on a carbon tax or similar mechanism.

To summarize, our assessment shows that fuel cells could play a relevant part in shipping’s decarbonization, should certain boundary conditions be fulfilled. Stakeholders across the shipping industry can use the information in this report for guidance as they each play their important roles in the adoption of this technology. For example, our results suggest that shipowners or operators may be able to affordably improve their assets’ environmental profile by phasing in fuel cells as described in our study. For technology providers, our report sheds light on the optimal commercial operational combinations of fuel cell technologies and alternative fuel pathways. From a policy perspective, the report provides guidance on what is possible and needed to enable fuel cells to contribute to shipping’s zero-carbon transition in the coming decades. Finally, this report uses insights from expert interviews and analysis to clarify industry perspectives and increase awareness of fuel cell technology and its potential to support decarbonization of shipping.