New vessels are increasingly expected to be dual or multi-fuel capable to remain competitive, this shift extends beyond storage and influences the full onboard fuel chain, from bunkering systems to engines and ventilation.
The shipping industry is undergoing significant development to meet the ambitious targets set by the International Maritime Organisation and national regulations for net zero. Greenhouse gas emissions need to be curbed for a better future and a healthier climate, and this means adopting technologies that pave the way for a greener future.
Shipowners are upgrading existing vessels to enhance efficiency and reduce emissions, and new vessels are being built to meet the net-zero standards. Research and development sectors are working around the clock to integrate various aspects of energy simulation, design, operational planning, and optimisation, as well as real-world data obtained from monitoring and measurements, to validate and predict model outcomes effectively.
Engineers are working on fuel tank designs and retrofits for shipowners to operate on alternative fuels like methanol and extend the operational life of vessels. As such, Design and technical aspects of fuel tanks and retrofitting are now under the spotlight. Recently, ClassNK approved in principle (AiP) to SRC for Methanol Superstorage – an innovative tank design concept that uses a Sandwich Plate System (SPS) technology to almost double shipboard storage capacity for methanol and ethanol. Alex Vainokivi, Innovation Manager, SRC Group, said the Methanol Superstorage tank delivers almost twice the fuel storage volume of a traditional tank, while the SPS provides a triple barrier for fire protection, leak prevention, and higher impact protection. Moreover, it can be retrofitted with minimal impact on the vessel’s general arrangement.
To help SeaNews understand more about ship fuel tank designs, retrofitting for a net-zero future, here’s what Alex Vainokivi said:
What are the biggest pain points in current ship fuel tank designs when transitioning from heavy fuel oil to low-carbon alternatives like methanol or ammonia?
The biggest challenge is space. Methanol’s energy density is less than half that of heavy fuel oil, meaning roughly 2.5 times more tank volume is needed for the same range. For ammonia, the volume penalty is even higher, about 3.5 times, since its energy density is lower and storage typically requires cylindrical pressure tanks. Methanol Superstorage tackles this issue for both methanol and ethanol fuels by reclaiming lost volume and minimizing the space penalty.
How do these impact vessel efficiency and compliance with IMO regulations?
Cofferdam requirements are often a dealbreaker for retrofits because many vessels simply don’t have the physical space to fit them. This makes compliance with IMO rules technically or economically unfeasible, especially when reduced fuel range forces more frequent bunkering. SRC’s system removes the need for conventional cofferdams, allowing compliance without as much sacrificing cargo or range, and keeping vessels both efficient and regulation-ready.
In your view, how have global decarbonisation targets, like the 2050 net-zero goal, reshaped the design priorities for fuel storage systems in the maritime industry over the past five years?
Global decarbonisation targets have completely redefined fuel system design priorities. New vessels are increasingly expected to be dual or multi-fuel capable to remain competitive.
This shift extends beyond storage and influences the full onboard fuel chain, from bunkering systems to engines and ventilation.
What misconceptions do shipowners have about retrofitting fuel tanks for green fuels, and how does this slow adoption?
Many still assume switching to methanol or ethanol automatically means installing bulky cofferdams and losing large portions of cargo space. That was true in early designs, but technologies like SRC’s Methanol Superstorage remove that limitation. The system provides equivalent or higher safety levels and has received Approvals in Principle from Lloyd’s Register, RINA, ClassNK, and the Panama Maritime Authority, with final approval evaluated on a project-specific basis. The misconception persists, slowing adoption that could already be technically and commercially viable.
Give an overview of the core engineering behind SRC’s Methanol Superstorage – how does the Sandwich Plate System enable up to 85 percent more storage capacity without cofferdams, and what materials or processes make it viable for retrofit installations?
It works by transforming part of the ship’s steel structure into the actual tank wall. The existing ship steel becomes the inner plate of a new composite structure. A new steel plate is then welded on top, creating a narrow cavity between the two. This cavity is filled with a specially engineered elastomer that cures in place, forming a solid core bonded permanently between the plates. This creates a compact, triple-layer wall-steel, elastomer, steel – that serves as both the tank boundary and containment system. It removes the need for conventional cofferdams, which frees up significant volume.
What were some of the key challenges in the installation of the Methanol Superstorage and what ROI did the shipowner see in terms of range /emissions reduction?
There are no major challenges in the installation process. SPS, which is a technology Methanol Superstorage uses, is a well-known method in shipbuilding with a 20-year track record. Methanol and Ethanol tanks are just a new application for it, designed by SRC. Therefore, the baby’s teething process is a long over with this one. The primary ROI drivers for shipowners adopting Methanol Superstorage are increased fuel capacity, which translates directly into operational benefits, reducing the need for bunkering and enabling longer operational windows between bunkering stops. Also, there is no need for inspections, maintenance, etc., as it is with cofferdams, which lowers the lifecycle cost.
Beyond methanol, how adaptable is SRC’s Superstorage approach to emerging fuels like e-ammonia or bio-LNG, and what regulatory hurdles might arise?
As same design regulations apply to ethanol. Methanol Superstorage is 100 percent adaptable to ethanol as well. We are also looking into other alternative fuels, but this R&D is at a very early stage.
What advice would you give to the owner of a typical container ship or tanker on prioritising fuel tank upgrades in a multi-fuel fuel?
Futureproof the Tank Spaces. Invest in tank designs that allow for future adaptation. As the marine fuel landscape continues to evolve, it’s critical that tank spaces are able to accommodate alternative fuels. For example, Methanol Superstorage can be used to store diesel or conventional fuel today, while being fully prepared for a future transition to methanol or ethanol. This approach reduces major changes later and supports a staged decarbonisation strategy.
