Q&A: Fuel Readiness – designing for flexibility in an uncertain fuel future
Insights on long-term fuel strategies from Deltamarin’s ship design team
With multiple regulatory pressures accelerating the transition away from conventional fuels, shipowners are increasingly being asked to commit to fuel choices that may not remain viable for the full operational life of their vessels. The need for long-term flexibility in fuel and engine strategy has never been more urgent – but preparing for future transitions requires a deep understanding of how technical decisions made today will shape a vessel’s adaptability tomorrow.
At Deltamarin, fuel readiness is not an add-on – it’s an integral part of smart ship design. From spatial planning and systems integration to lifecycle cost modelling and scenario analysis, the company’s engineering teams work closely with owners to ensure their newbuilds are not only compliant at delivery but will remain competitive in an evolving market.
In this Q&A piece, Project Engineers Juuso Reunamo and Joonas Määttänen explain how Deltamarin helps clients balance today’s fuel strategy with tomorrow’s uncertainty. They explore real-world examples of cost trade-offs, conversion planning, class notations and the cascading impact of fuel decisions on non-propulsion systems – helping customers design vessels that will stay efficient, adaptable and valuable for decades to come.
- What’s driving the urgency around fuel readiness – and how do MEPC 83 and FuelEU Maritime change the equation for shipowners?
- How should shipowners assess what level of fuel readiness is right for their fleet – and what frameworks or tools can help guide that decision?
- Can fuel readiness actually save money in the long run – and what do the real numbers look like?
- What kind of technical decisions today will have the biggest impact on fuel flexibility tomorrow?
- How do alternative fuels like methanol and ammonia affect the performance of ship systems beyond propulsion?
- With fuel technologies still evolving, how can shipowners avoid locking into the “wrong” fuel pathway or engine design?
- What are the most common missteps you see when companies plan for alternative fuels – and how can they be avoided?
- What’s the real value behind fuel readiness class notations – and are they always worth pursuing?
- How does Deltamarin support clients in integrating fuel readiness from first discussions to vessel delivery?
- What risks or unknowns still remain in the fuel readiness landscape – and how do you help clients prepare for them?
1. What’s driving the urgency around fuel readiness – and how do MEPC 83 and FuelEU Maritime change the equation for shipowners?
The regulations set by MEPC 83 (May 2025) and FuelEU Maritime are giving a clear and strong signal that now is the time to consider how vessels being built today can fulfil environmental requirements throughout their operational lifetime. The impact is not limited to fuel choice; it extends to how fuels are produced and distributed, affecting operational and investment strategies alike.
At MEPC 83, the IMO agreed on midterm GHG reduction measures, setting a target of reducing the carbon intensity of shipping by at least 40% by 2030 versus 2008 levels, and pushing toward a 70–80% GHG reduction by 2040. In parallel, FuelEU regulations will come into effect in 2025, setting escalating annual limits on GHG intensity for ships calling at EU ports, with a 2% reduction target in 2025 and up to 80% by 2050. This will directly affect vessel design and fuel strategies, as compliance will require significant emissions reductions year on year.
Critically, these regulations have broad geographic reach. While some owners previously planned to reposition or trade vessels outside the EU to avoid regional regulations, the new global IMO standards make that a less viable “Plan B”. Ships will need to comply with increasingly stringent emissions standards wherever they operate, reinforcing the need for long-term flexibility in vessel design.
While the ship systems themselves are generally agnostic to the production method of alternative fuels, the environmental performance and regulatory compliance of the fuels are not. Over time, ships will likely shift from conventional fuels to greener blends or entirely renewable alternatives. Increasingly, regulations are moving from a tank-to-wake (TtW) approach – measuring only exhaust emissions – to a well-to-wake (WtW) framework that considers the entire fuel lifecycle, from production to combustion. For example, FuelEU sets GHG intensity limits based on WtW emissions, meaning that both upstream production and onboard combustion performance affect compliance. Even for fuels like bio- or renewable diesel, which are close in characteristics to conventional fuels, there are important considerations regarding compatibility, availability, lifecycle emissions and cost.
Today, the majority of ships adopting alternative fuels are dual-fuel (DF) vessels. For example, vessels operating on MGO and LNG already enjoy a degree of flexibility, as both fossil and bio/synthetic blends can be used in these systems. However, if operational or regulatory pressures push toward adopting other fuels – such as methanol or ammonia – a conversion will be required. This is where securing a high level of fuel readiness can deliver significant benefits by reducing the complexity, cost and downtime associated with future adaptations.
2. How should shipowners assess what level of fuel readiness is right for their fleet – and what frameworks or tools can help guide that decision?
When considering the appropriate level of fuel readiness, the starting point of the vessel is critical. Ships that rely solely on conventional fuels typically have the highest need for fuel readiness upgrades but also face the greatest technical challenges due to limited existing compatibility in systems and arrangement. In contrast, some of the dual-fuel (DF) LNG vessels recently delivered or now under construction are built with tanks that can be adapted for alternative fuels like ammonia or methanol, which can significantly reduce the complexity and cost of future conversions. However, this is not automatically the case with standard LNG tanks on existing vessels.
To guide owners through these strategic decisions, Deltamarin divides fuel readiness into three primary levels:
- MINIMAL READINESS
This is the most basic level, designed to ensure that the vessel can technically be converted in the future. It typically involves documentation and pre-approval drawings showing how the vessel could be modified but with no physical space reservations or installed equipment. Engine conversion kits may not be available yet but are planned for future release. However, executing a conversion from this baseline can be highly expensive and time-consuming, involving the installation of new tanks, re-routing of pipes and cabling, upgrading safety systems and possibly even replacing engines – all of which would cause significant downtime. - INTERMEDIATE READINESS
This level aims to reduce future conversion costs and time by incorporating some physical preparations during the initial build. The design ensures that critical components – such as engines – can be converted with available kits and that the vessel layout includes access routes that allow these components to be installed or removed without the need for structural modifications. These access routes refer to predefined paths within the vessel, such as removable decks panels, hatches or bulkhead openings, that are sized and located to support both initial installation and future hauling or maintenance. Tanks are either already suitable or require only minor modifications for alternative fuels. There is space reserved, or pre-installed infrastructure, for auxiliary systems and fuel-handling equipment. The hazardous and non-hazardous zones are already planned with future fuels in mind, minimising later regulatory hurdles. - FULL READINESS
This level equips the vessel to be immediately capable of operating on the alternative fuel – even if the actual fuel is not yet commercially available or bunkering infrastructure is limited. It includes fully installed fuel storage, supply systems and engines either capable of DF operation or pre-certified for future conversion. In some cases, engine manufacturers may offer conversion kits for installation post-delivery, meaning the vessel is only a few minor steps away from operational readiness on the new fuel. This level of readiness gives the highest future flexibility but also involves the highest upfront investment.
In many projects, a hybrid approach can also be advantageous – applying a full readiness level for one primary alternative fuel, while maintaining intermediate or minimal readiness for secondary options. This ensures that owners are not overinvesting but still retain flexibility if market conditions or regulations shift.
The optimal fuel-readiness strategy depends heavily on the ship type, operational area, trading profile, fuel availability and the owner’s long-term business plan. That’s why at Deltamarin, we support clients with advanced scenario modelling and simulation tools. These models incorporate not only the vessel’s operational profile but also projected GHG emissions pathways, cargo capacity impacts and endurance trade-offs under various fuel strategies.
Importantly, all current and emerging regulatory requirements – including the latest IMO and FuelEU Maritime targets – are integrated into these simulations. This allows our clients to make informed, data-driven decisions about the right level of fuel readiness, the right timing for conversion and the most resilient path to long-term compliance.
3. Can fuel readiness actually save money in the long run – and what do the real numbers look like?
Fuel readiness is often viewed as an additional upfront cost – but when properly considered, it is fundamentally an investment in lifecycle value and operational flexibility.
Understanding the cost dynamics of fuel storage is key. LNG and ammonia, for instance, are both liquefied gases and can be stored in similar cryogenic tanks – but the tank material and design strength must be carefully specified to handle the specific properties of either LNG or ammonia, or ideally both. Methanol, on the other hand, can be stored in coated structural tanks, requiring different configurations including protective cofferdams for safety.
- If designed carefully, an LNG tank can also be certified for ammonia and even methanol with only minor modifications.
- In contrast, a methanol-designed tank cannot be safely upgraded to store LNG or ammonia later.
- Some conventional fuel tanks can be designed with structural reinforcements or reserved space to allow easier conversion to methanol use in the future.
- Investing in readiness at the newbuilding stage – when systems are already being installed – is significantly cheaper than trying to retrofit these capabilities later, when structural modifications, steel work and system reconfigurations will add substantial cost and downtime.
- Conversely, if fuel simulations and regulatory projections show that the selected initial fuel will meet long-term targets, a lower readiness level can be applied to avoid overinvesting.
For example, in one feasibility case study, we compared two configurations: a standard LNG fuel system and an LNG system with an ammonia-ready tank design. The cost increase for preparing the tank for future ammonia use at the newbuild stage was approximately 20% over the baseline LNG system. While this adds modest cost upfront, it significantly reduces long-term risk.
In contrast, if a vessel with a conventional LNG system were later required to convert to ammonia, the cost implications would be far higher. Not only would the original LNG tank – which may have cost around USD 6 million – become obsolete but the retrofit would require an entirely new ammonia-compliant tank, plus major structural modifications and system adaptation. This could bring total costs up to USD 20 million – more than 200% higher than the ammonia-ready option at the newbuild stage. This includes scrapping the existing tank, procuring and installing a new one, and undertaking extensive steel work – particularly if the tank is located deep within the vessel.
The takeaway is clear: when future fuel transitions are even a moderate possibility, it is far more cost-effective to prepare at the outset. The marginal investment today avoids substantial conversion costs, downtime and technical challenges later.
At Deltamarin, we use detailed lifecycle cost modelling and simulation tools to help clients understand the total cost of ownership implications of their fuel readiness decisions. By balancing initial CAPEX against future OPEX and retrofit risks, we ensure that owners are making informed, financially sound decisions, optimising their investment not just for today’s regulations but for decades of operational flexibility.
4. What kind of technical decisions today will have the biggest impact on fuel flexibility tomorrow?
Beyond the engine room, spatial and structural considerations play a major role in determining how straightforward, or costly, future conversions will be. Key examples include:
- Bunker station layout: It’s essential to position bunker stations during newbuilding to meet the safety regulations of alternative fuels, such as segregation requirements for hazardous areas. If designed thoughtfully from the start, this can usually be achieved with minimal or no additional cost. However, if not considered early, costly and complex structural modifications may be required later to meet safety standards for alternative fuels like ammonia or methanol.
- Ventilation systems and vent mast design: Adequate separation distances between hazardous and non-hazardous areas must be maintained. If insufficient distance is allowed during initial design, extensive retrofits might be necessary — including repositioning major components or raising vent masts. Taller vent masts could also inadvertently impact vessel air draft, restricting access to certain ports and waterways, which adds significant operational limitations.
- Tank space and routing: Providing flexible spaces and unobstructed routes for future installation of additional fuel tanks, piping or auxiliary equipment (e.g. fuel treatment systems) can dramatically ease conversion efforts later. Structural reinforcement or space reservation now prevents costly steelwork and downtime later in the vessel’s life.
At Deltamarin, we take an integrated design approach that considers not just today’s operational needs but anticipates future fuel pathways. Through early-stage scenario modelling and layout optimisation, we help clients avoid design bottlenecks and costly constraints – ensuring that investments made today preserve operational and regulatory flexibility for decades to come.
5. How do alternative fuels like methanol and ammonia affect the performance of ship systems beyond propulsion?
As tightening regulations drive up the cost of emissions and future fuels, it has become increasingly important to design energy-efficient ships that maximise the use of all available energy – including waste heat that is typically recovered from exhaust gases. However, alternative fuels like methanol and ammonia introduce a significant technical challenge that is often underestimated in early designs.
One key issue is that methanol and ammonia combustion produces significantly less waste heat versus conventional fuels like marine diesel oil (MDO) or LNG. This reduction has direct and indirect implications for onboard systems that either rely on thermal energy recovered from exhaust gases or are affected by their availability, including:
- Steam turbines
- Organic Rankine Cycle (ORC) units
- Auxiliary boilers
- Exhaust gas boilers
- Heating and ventilation systems
If the vessel is equipped with waste heat recovery systems (e.g. for generating electricity or process heat) and these systems are designed based on the thermal output of conventional fuels, they may become oversized or underutilised when the ship transitions to alternative fuels. In such cases, exhaust gas boilers may no longer deliver sufficient heat output, and the vessel may need to rely more heavily on auxiliary boilers to meet energy demands. This shift can lead to higher fuel consumption, increased OPEX and, in some cases, render advanced waste heat recovery equipment economically unviable.
In one recent study, Deltamarin identified that switching from diesel to methanol would result in an approximate 30% drop in available exhaust gas heat. To address this, the ship’s heating system was re-engineered – transitioning from a traditional steam-based configuration to a hot water-based system. The updated design focused on maximising heat recovery from the engine’s high-temperature (HT) cooling water, which is less affected by the fuel type and provides a more stable heat source. While some energy was still recovered from the exhaust gases, the shift in focus enabled the vessel to maintain reliable heating efficiency despite the lower thermal output of methanol combustion. Over the vessel’s lifetime, this design adaptation helped ensure energy efficiency, reduce dependency on auxiliary boilers and maintain optimal performance of both heating and ORC systems while reducing lifecycle emissions.
It is important to understand that there is no one-size-fits-all solution. The optimal configuration depends heavily on vessel type, operational profile, voyage patterns and anticipated fuel pathways. This is why Deltamarin applies a systems-level approach to fuel readiness – not only considering propulsion but also carefully evaluating the cascading impact of fuel choices on auxiliary systems and long-term vessel operability. By doing so, we help clients avoid hidden inefficiencies and future-proof their ships against evolving energy realities.
6. With fuel technologies still evolving, how can shipowners avoid locking into the “wrong” fuel pathway or engine design?
Fuel readiness opens the door to multiple future pathways, even in cases where today’s fuel solution might seem like a safe bet. In many instances, owners operating vessels in specific regions – for example, where LNG, biogas and eventually synthetic gas are readily available – might opt for LNG propulsion as the obvious choice. LNG, along with its bio- and synthetic derivatives, offers lower emissions and some compliance assurance for the near future.
However, the market and regulatory landscape can shift rapidly. If future availability or economics change – for instance, if LNG supply becomes constrained or synthetic gas adoption is slower than expected – owners could find themselves exposed. Without fuel readiness built in, the investment in LNG-specific infrastructure could become a sunk cost. In contrast, if the vessel is designed with a degree of flexibility, that risk can be mitigated.
Fuel-ready designs allow for this flexibility. For example:
- Spaces and systems initially designed for LNG tanks and fuel handling can be dimensioned and arranged to accommodate alternative fuels like ammonia or methanol with minimal modifications.
- Utility routes, structural supports and hazardous zoning can be pre-engineered to be adaptable, reducing the complexity and cost of future conversions.
- Multi-pathway strategies: Vessels can be designed to maintain optionality for several fuel types, weighting readiness levels depending on likelihood — for instance, full readiness for a primary alternative and intermediate readiness for a secondary fuel.
This approach derisks the vessel’s operational future by keeping multiple compliance and fuel strategies open – even if the preferred fuel pathway today ultimately changes.
At Deltamarin, we actively support clients in mapping likely fuel pathways based on operational areas, trading routes, port bunkering developments and regulatory forecasts. Using advanced scenario modelling, we help clients design vessels with built-in flexibility – balancing today’s fuel strategy with tomorrow’s uncertainties. In an environment where fuel markets and emissions regulations are evolving rapidly, designing for adaptability is one of the most critical ways to protect long-term asset value and operational resilience.
7. What are the most common missteps you see when companies plan for alternative fuels – and how can they be avoided?
When it comes to planning for alternative fuels, some of the most common – and costly – missteps can happen early, during the concept and basic design stages. Frequent pitfalls might include:
- Poor space planning: Not allocating enough space or incorrectly zoning areas for future fuel systems (e.g. tanks, piping, ventilation systems, fuel treatment equipment) can dramatically increase the cost and complexity of retrofits later.
- Material compatibility issues: Selecting tank coatings, piping materials or safety equipment that are not compatible with future fuels such as methanol or ammonia, requiring expensive replacements.
- Inadequate hazardous area planning: Failing to anticipate the stricter safety zones needed for alternative fuels can result in major structural changes or limitations on cargo space when conversions are attempted.
- Overlooking auxiliary systems: As discussed earlier, designing waste heat recovery, ventilation, and energy management systems without considering future fuel thermal profiles can lead to inefficiencies or obsolescence.
At Deltamarin, we help clients avoid these traps by leveraging our extensive experience across multiple ship types, fuel technologies and design stages. Working across diverse vessel segments – from tankers and bulkers to cruise and offshore units – exposes us to a wide range of fuel strategies and technical innovations. This broad exposure encourages out-of-the-box thinking and the cross-pollination of ideas that may not be visible when focusing only on one ship type or market.
Moreover, because we are deeply involved throughout the entire design process – from initial concept design, through class approvals to detailed engineering – we are able to integrate lessons learned at each stage into subsequent projects. This continuity ensures that our designs are not only innovative but also practical, class-compliant and operationally sound.
Quite often, the final vessel delivered is very close to the first concepts we developed – a testament to the robustness of our early design work and the depth of our technical expertise. It is this approach that has made us a trusted partner to both shipyards and shipowners over many years. Focusing only on a single vessel type or fuel can easily lead to blind spots, causing minor-seeming oversights that, if left unaddressed, may later have a disproportionate impact on cost, safety or operational flexibility. Our broad, integrative approach ensures that clients are protected from these avoidable risks.
8. What’s the real value behind fuel readiness class notations – and are they always worth pursuing?
Most classification societies offer fuel readiness notations, and while the naming and specifics vary slightly, the basic structure is broadly similar. Typically, notations fall into three main categories:
- Design readiness: Indicates how the vessel could be modified to accommodate alternative fuels based on design documentation.
- Tank readiness: Focuses on the preparedness of the fuel tanks – materials, structure and safety measures.
- Engine and boiler readiness: Covers the propulsion and auxiliary machinery’s capacity for future conversion.
Within each category, there is usually a three-tiered scale:
- A: Conversion is possible in the future but no physical preparations are made (essentially a “paper” readiness, low cost).
- B: Partial preparation – for example, engine conversion kits are available or the design accommodates future retrofitting without major structural changes.
- C: Full readiness – physical modifications are already in place; minimal work would be needed for full fuel switch compliance.
For example, a vessel might have a B-level main engine (conversion kit available), an A-level auxiliary engine (future conversion possible but not yet prepared), and a C-level tank (fully built to the specifications required for alternative fuels).
However, it is important to note that class notations can sometimes offer a false sense of security. Many A and B levels involve little to no physical investment and are more about documentation and pre-approval than tangible shipyard work. As a result, while these notations can be obtained at relatively low cost, they do not necessarily reduce the future conversion burden.
Moreover, not everything that matters is captured by class notations. For instance, small but critical design features such as:
- Dimensioning fuel handling room ventilation to accommodate more stringent requirements for fuels like ammonia.
- Future-proofing hazardous zoning and space for fuel treatment systems.
These elements often fall outside formal class criteria but can have a significant impact on future conversion costs, shipyard downtime, and regulatory compliance. If considered thoughtfully at the newbuilding stage, they can be included at negligible extra cost, but save substantial time and money during future retrofits.
At Deltamarin, we go beyond simply aiming for notations. We work closely with clients to critically assess which levels of readiness deliver real operational and financial value – and where it’s worth investing a little more at the design stage to avoid bigger expenses later. By combining regulatory insight, technical detail and cost-benefit analysis, we help owners avoid superficial readiness and instead achieve true future-proofing for their fleet.
9. How does Deltamarin support clients in integrating fuel readiness from first discussions to vessel delivery?
Integrating fuel readiness into vessel design requires a strategic, lifecycle approach – not just technical adjustments but a deep understanding of how future fuel choices will impact operational, commercial and regulatory performance over the vessel’s lifetime.
At Deltamarin, we engage with clients from the very earliest project stages, starting with comprehensive feasibility studies. These studies evaluate the impact of different fuel options on:
- Cargo capacity: Alternative fuels often require larger or differently shaped tanks, which can reduce available cargo space.
- Vessel endurance: Fuel energy density and storage requirements influence voyage range and bunkering frequency.
- Overall vessel cost: We assess the trade-offs between initial capital expenditures and long-term operational costs under different fuel pathways.
- Comparative analysis: Clients receive side-by-side comparisons of fuels like LNG, methanol, ammonia and future synthetic options – factoring in availability, price trends and regulatory compliance risks.
This process helps clients see not just how a particular fuel will fit their intended operations but also how future shifts in fuel markets or regulations could affect the vessel’s performance and value.
Importantly, these feasibility studies are also used to drive decisions about the appropriate level of fuel readiness. Clients can model different readiness levels (minimal, intermediate, full) based on the chosen fuel strategy and operational profile. Armed with this data, they can make informed decisions about:
- Which readiness investments to incorporate at the newbuild stage.
- How to future-proof their vessels without overinvesting in unnecessary systems.
- Where to maintain flexibility in layout, equipment selection and safety zoning.
Throughout this process, Deltamarin provides not just technical inputs but also operational and financial modelling, ensuring that the readiness strategy is aligned with your specific business model, risk appetite and long-term goals. Examples of our digital design methods for simulating ship energy consumption and regulatory costs can be found in “white papers and publications” in the Studies & Consulting section of our website. These services are a natural part of our newbuilding projects.
From early consultations through to concept design, class approvals, detailed engineering and construction support, we work as an integrated partner across the vessel lifecycle. This collaborative, data-driven approach ensures that fuel readiness is not an afterthought but a fully embedded part of the vessel’s DNA – helping owners safeguard their investments against regulatory shifts, fuel market changes and evolving charterer expectations.
10. What risks or unknowns still remain in the fuel readiness landscape – and how do you help clients prepare for them?
Despite the growing momentum around alternative fuels, there are still significant uncertainties that shipowners must navigate when preparing for the future. Some of the main risks include:
Regulatory evolution: While the IMO’s current midterm measures and the FuelEU Maritime regulations provide a framework, the details are still evolving – particularly around lifecycle emissions (well-to-wake accounting) and future fuel certification standards. Regional regulations may also diverge, creating a patchwork of requirements that ships must meet in different trading areas.
Fuel availability and infrastructure: Although fuels like LNG, methanol and ammonia are technically viable, global bunkering infrastructure remains uneven. Betting on a fuel too early – or without ensuring long-term supply reliability – can expose vessels to operational risks or unplanned retrofitting costs.
Technology readiness: Engine and fuel-system manufacturers are still developing and refining dual-fuel and alternative fuel solutions. Delays in engine certification, supply chain constraints or unexpected technical challenges can impact the timelines for safe and efficient fuel adoption.
Market dynamics: Fuel pricing, carbon taxation schemes and emissions trading systems are volatile and can shift quickly, affecting the cost-competitiveness of different fuels over the vessel’s lifetime.
At Deltamarin, we help clients manage these uncertainties strategically rather than reactively. Our approach is to focus not only on current regulatory compliance but also on real emissions reduction and long-term operational efficiency. Rather than chasing regulatory targets that may shift, we guide clients toward robust, resilient design strategies that:
- Minimise lifecycle emissions under a wide range of future scenarios.
- Preserve operational flexibility through modular, adaptable fuel system designs.
- Incorporate scenario modelling that stress-tests vessel performance against different fuel price forecasts, regulatory regimes and technology adoption curves.
By prioritising the most efficient vessel design, owners can position themselves well for future regulations – many of which will become more stringent over time. Achieving genuine efficiency and low emissions cannot be reached simply by meeting today’s minimum regulatory requirements; it requires forward-looking thinking that anticipates where the industry is heading.
Our mission is to ensure that the vessels we design today are not only compliant at delivery but also competitive and resilient for decades to come, regardless of how the regulatory and fuel landscape evolves.
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