Life Cycle Analysis of Fuels in Ship Operations

Methodologies, Emission Accounting, and Feasibility for the Maritime Sector

1. Introduction to Life Cycle Analysis (LCA) in the Maritime Sector

The global maritime industry faces increasing pressure to decarbonize, necessitating a comprehensive understanding of the environmental impact of marine fuels. Life Cycle Analysis (LCA) emerges as a critical tool in this endeavor, providing a standardized and holistic methodology for assessing greenhouse gas (GHG) emissions across the entire fuel value chain. This section introduces the fundamental principles of LCA, its structured phases, and its specific application within the maritime context.

1.1 Defining Life Cycle Analysis (LCA) and its Purpose

Life Cycle Assessment (LCA) is a quantitative method for evaluating the environmental impact of a product or service throughout its entire lifespan, often referred to as a “cradle-to-grave” perspective.1 This methodology has been standardized by the International Organization for Standardization (ISO) 1, ensuring a consistent and rigorous approach to environmental assessment. The primary objective of LCA is to generate scientific and objective evidence that supports informed decision-making for environmental improvements.1 By quantifying resource and energy inputs, as well as various emissions at each stage of a product’s or service’s life cycle, LCA aims to prevent the unintended consequence of merely shifting environmental problems from one phase of the life cycle to another, or from one environmental issue to another.1

For the maritime sector, LCA is recognized as an appropriate and essential tool for evaluating the environmental performance of marine fuels.1 The International Maritime Organization’s (IMO) LCA Guidelines specifically focus on assessing GHG emissions across the full life cycle of marine fuels, encompassing everything from their production to their transport and eventual use onboard ships.2 The emphasis on LCA being standardized by ISO and its purpose to provide objective evidence underscores a fundamental drive towards global harmonization in environmental reporting. For an international industry like shipping, where fuels are sourced globally and vessels operate across numerous jurisdictions, a universally accepted and verifiable methodology is paramount. This standardization facilitates equitable comparison of different fuels, mitigates the risk of regulatory arbitrage, and builds essential trust in decarbonization claims, which is vital for attracting investment and ensuring consistent compliance across a diverse global fleet.

Well-to-Wake (WtW) and Well to Tank (WtT) concept

1.2 The Four Phases of LCA (ISO 14040 Standard)

According to the ISO 14040 standard, conducting an LCA involves four interdependent and often iterative phases.1 This iterative nature means that as new data becomes available or understanding deepens, earlier phases may require refinement, allowing for continuous improvement and adaptation of the assessment.

• Goal and Scope Definition: This initial phase is crucial for establishing the study’s purpose, defining the system under analysis, and setting its boundaries.1 A key element here is the “functional unit,” a quantitative measure representing the system’s function, which enables meaningful comparisons between different products or services that fulfill the same purpose.1 For marine fuels, a functional unit might be the energy delivered (e.g., per megajoule) or the distance transported (e.g., per ton-mile).
• Inventory Analysis: This phase involves constructing a detailed flow model based on the defined system boundaries.1 It systematically collects data on all resource inputs (e.g., raw materials, energy) and environmental outputs (e.g., air pollutants, water pollutants, solid waste) at every stage of the fuel’s life cycle.1 This includes everything from feedstock acquisition and processing to distribution, onboard use, and potential disposal or recycling.2 The elemental flows of resources and emissions connected to each process are meticulously quantified.1
• Impact Assessment: In this mandatory phase, the quantified elemental flows from the inventory analysis are classified into various environmental impact categories, such as global warming, acidification, or eutrophication.1 These flows are then characterized to calculate their relative contributions to these impacts. For instance, different greenhouse gases (e.g., methane, nitrous oxide) are aggregated into a single indicator, typically carbon dioxide equivalent (CO2e), to represent their global warming potential.1 An LCA without this impact assessment step is considered a life cycle inventory analysis rather than a full LCA.1
• Interpretation: The final phase involves summarizing and discussing the results derived from either or both the inventory analysis and the impact assessment.1 This synthesis forms the basis for drawing robust conclusions and formulating actionable recommendations, guiding decision-making for environmental improvements.1

The explicit mention of LCA as an iterative process carries significant implications for the maritime sector’s decarbonization efforts. Given the rapid evolution of new fuel technologies—such as hydrogen, ammonia, and methanol—and their associated production methods 4, environmental assessment cannot be a static, one-time exercise. The iterative nature of LCA means that as supply chains mature, production efficiencies improve, or new scientific data emerges, assessments will need continuous refinement. This dynamic approach necessitates a flexible regulatory framework and ongoing monitoring, which in turn drives continuous innovation and adaptation within the maritime sector, rather than adhering to a fixed, prescriptive set of rules.

1.3 Application of LCA to Marine Fuels and GHG Emissions

The IMO’s LCA Guidelines provide a specific framework for defining GHG emissions from marine fuels across their entire life cycle. This framework distinguishes between “Well-to-Tank” (WtT) for upstream emissions (from feedstock extraction to fuel bunkering), “Tank-to-Wake” (TtW) for onboard emissions, and “Well-to-Wake” (WtW) for the total life cycle emissions.2

LCA is crucial for identifying suitable alternative low- or zero-GHG fuel candidates for shipping by comprehensively assessing the full spectrum of GHG emissions involved throughout their life cycle, including the often-overlooked earlier stages of production.3 The IMO’s LCA Guidelines are highly detailed, classifying fuel pathways based on feedstock type, origin, production method, and energy used, specifying a total of 128 different fuel pathways.2 To facilitate this assessment, the Guidelines specify a technical tool known as the “Fuel Lifecycle Label” (FLL), which collects and conveys information relevant to the life cycle assessment of marine fuels and energy carriers.2 This FLL requires verification and certification by a third party, with further guidance expected from the IMO.2

The explicit focus on comprehensively assessing GHG emissions throughout the entire life cycle of fuels, including their production stages, directly addresses the critical issue of “carbon leakage” or “burden shifting”.7 By encompassing the entire value chain, LCA ensures that efforts to reduce emissions at the ship’s exhaust do not inadvertently lead to increased emissions during the fuel’s production or transport. This holistic approach is fundamental to achieving genuine and verifiable decarbonization within the maritime industry, preventing a scenario where the sector appears cleaner on paper while its upstream activities contribute disproportionately to global GHG emissions.

2. Understanding Fuel Emission Accounting: Well-to-Wake (WtW) and Well-to-Tank (WtT) Concepts

To effectively manage and reduce greenhouse gas emissions in the maritime sector, specific methodologies for calculating fuel-related emissions have been developed. These methodologies delineate different stages of a fuel’s life cycle, providing varying scopes for emission accounting. This section elaborates on the Well-to-Tank (WtT), Tank-to-Wake (TtW), and the comprehensive Well-to-Wake (WtW) approaches, which are central to GHG emission calculations for marine fuels.

2.1 Well-to-Tank (WtT) Emissions: The Upstream Perspective

Well-to-Tank (WtT) emissions represent the total greenhouse gas emissions associated with the production, processing, and distribution of a specific fuel type from its initial point of extraction or primary production (the “well”) to the moment it is stored in the ship’s fuel tank.2 These emissions are frequently referred to as “upstream” or “indirect” emissions.3

The scope of WtT encompasses a broad range of activities that occur before the fuel is consumed onboard a vessel. This includes emissions generated during feedstock extraction (e.g., crude oil, natural gas, biomass), refining processes, and all forms of transportation (e.g., by pipelines, rail cars, trucks, or ships) to reach distribution points and bunkering facilities.2 For alternative energy carriers like electricity used for shore power, WtT emissions would include those from electricity generation (e.g., power plants) and transmission and distribution losses.10 The IMO’s LCA Guidelines specifically detail methods for calculating the GHG intensity of this Well-to-Tank phase, covering all emissions from feedstock extraction through production, transport, and bunkering.2

The concept of WtT emissions reveals that a substantial portion of a fuel’s environmental impact occurs long before it is even loaded onto a vessel. This implies that focusing solely on emissions at the ship’s exhaust would severely underestimate the true carbon footprint of maritime operations. A thorough understanding of WtT is therefore crucial for identifying and targeting opportunities for emission reductions throughout the entire fuel supply chain. This perspective incentivizes the development and adoption of cleaner production methods and prevents the creation of an illusion of decarbonization when emissions are merely displaced upstream.

2.2 Tank-to-Wake (TtW) Emissions: The Onboard Use Perspective

Tank-to-Wake (TtW) emissions, sometimes referred to as “tank-to-propeller” 3 or “tank-to-wheel” 9, specifically account for the greenhouse gas emissions produced by a ship’s engine during its operational phase, once the fuel has been loaded into the vessel’s tanks.2 These are commonly known as “downstream” emissions.3

The activities included in TtW calculations primarily involve the combustion or conversion of fuel onboard the vessel. This includes the release of key greenhouse gases such as carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) resulting from the engine’s operation.3 A significant limitation of this approach is that it does not incorporate any emissions related to how the fuel was produced, processed, or transported to the vessel.8

2.3 Well-to-Wake (WtW) Emissions: The Holistic View

Well-to-Wake (WtW) represents the most comprehensive assessment of total greenhouse gas emissions across the entire life cycle of a marine fuel.2 It integrates both the Well-to-Tank (WtT) and Tank-to-Wake (TtW) components, providing a complete picture of the fuel’s environmental impact from its origin to its final use onboard a ship.2

This holistic perspective encompasses every stage: from primary production or feedstock extraction, through all processing, transport, and bunkering operations, and finally, the fuel’s combustion or conversion during its use onboard ships.2 The WtW approach is considered vital for understanding all emissions and other environmental impacts associated with fuel production, storage, distribution, and onboard consumption.7 It is increasingly seen as the main driving force behind the introduction of alternative fuels in the maritime sector, as it ensures that the intended GHG reduction benefits are genuinely achieved across the entire value chain.7

The WtW concept, by explicitly combining WtT and TtW, necessitates a fundamental shift from isolated operational considerations to integrated supply chain management for fuel emissions. This implies that ship operators and fuel suppliers must engage in close collaboration, sharing data and insights across the entire value chain to accurately track and reduce emissions. Furthermore, future fuel procurement decisions will increasingly depend not just on traditional factors like price and availability, but also on the verifiable WtW carbon intensity of the fuel. This shift will push for greater transparency and potentially lead to new contractual agreements that span the full life cycle of the fuel, driving comprehensive decarbonization efforts.

The following table provides a clear comparison of these three critical emission accounting concepts:

3. Comparative Analysis: WtW vs. TtW/WtT for Maritime GHG Emissions

The choice of methodology for calculating greenhouse gas (GHG) emissions profoundly impacts how fuels are classified, incentivized, and regulated within the maritime sector. This section critically compares the Well-to-Wake (WtW) and Tank-to-Wake (TtW) approaches, highlighting their key distinctions, the implications for fuel assessment, and the compelling advantages of adopting a comprehensive WtW methodology.

3.1 Key Differences and Implications for Fuel Classification

The fundamental distinction between Well-to-Wake (WtW) and Tank-to-Wake (TtW) lies in their scope: WtW considers all emissions throughout a fuel’s entire life cycle, whereas TtW focuses exclusively on emissions generated during its use onboard the vessel.8 This difference has significant ramifications for how fuels are classified, particularly concerning their “carbon-neutral” status.8

Under a Tank-to-Wake (TtW) approach, fuels with zero tailpipe emissions, such as hydrogen or battery-electric power, are favored and deemed carbon-neutral, irrespective of the emissions associated with their production.8 For example, under a strict TtW framework, all forms of hydrogen—whether “gray hydrogen” produced from natural gas with significant GHG emissions, or “green hydrogen” produced using renewable electricity with minimal emissions—would be considered carbon-neutral because they release no GHGs when consumed on a vessel.8 This narrow focus can, however, misrepresent the total climate and health impacts by disregarding the upstream processes of fuel production and transport.8

Conversely, a Well-to-Wake (WtW) approach accounts for the entire process, providing a more accurate differentiation between fuels based on their full life cycle impact. In this context, green hydrogen would be recognized as carbon-neutral, while gray hydrogen would not, due to its substantial upstream emissions.8 Similarly, a fuel like renewable natural gas, which can achieve carbon-negative status over its entire life cycle, would not qualify as carbon-neutral under TtW because it emits GHGs during combustion. However, its full environmental benefit would be recognized under a WtW assessment.8 WtW directly addresses and avoids the critical problem of “burden shifting,” where GHG emissions are merely moved upstream or downstream in the fuel supply chain rather than genuinely reduced.7

The stark contrast in “carbon-neutral” classification between TtW and WtW, particularly evident in the hydrogen example, reveals a critical risk for the maritime industry: the potential for “greenwashing”.7 If regulations are based solely on TtW, there is a strong, albeit misleading, incentive to adopt fuels that appear clean at the tailpipe but are associated with high upstream emissions. This not only misrepresents the actual climate impact but also risks misdirecting significant investment into solutions that do not contribute to genuine net-zero goals. Ultimately, such a narrow focus could undermine the industry’s overall decarbonization efforts and erode public trust in its environmental commitments.

3.2 Benefits of a Well-to-Wake Approach

The adoption of a Well-to-Wake (WtW) approach offers numerous compelling benefits that extend beyond mere compliance, driving genuine decarbonization and fostering sustainable practices across the maritime fuel value chain.

• Ensures Actual GHG Reduction Benefits: By encompassing emissions from production, storage, and distribution, WtW guarantees that the intended GHG reduction benefits from fuels are genuinely achieved, preventing the mere relocation of emissions within the supply chain.7 This comprehensive view provides ship operators and regulators with greater control over the outcomes of GHG emission reduction plans.7
• Avoids Burden Shifting: WtW directly addresses the problem of emissions being moved upstream or downstream in the fuel supply chain, ensuring accountability across the entire life cycle.7
• Accurate Comparison and Benchmarking: Consistent application of WtW allows for precise and fair comparison of carbon reduction outcomes across different fuels and varying regulatory regimes, preventing misleading assessments.7 This enables informed decision-making when selecting sustainable alternative fuels.7
• Maximum Regulatory Compatibility: As the broadest framework for assessing fuel carbon intensity, WtW offers the widest applicability across diverse national and international regulatory frameworks.7 Notably, regional initiatives like the EU’s FuelEU Maritime already assess fuels based on their lifetime carbon emissions (WtW).7
• Precise Application of Carbon Levies: WtW ensures that all carbon emissions associated with fuel use are accounted for, facilitating a more precise and equitable application of carbon levies, taxes, or incentive schemes.7 This comprehensive accounting can also provide ship operators with greater control over the pricing of low-carbon fuels by offering an accurate representation of their true carbon intensity.7
• Widens Scope for Innovation and Cost Reduction: The WtW methodology expands the possibilities for reducing fuel carbon intensity beyond just onboard combustion. It opens new avenues for economic reductions through optimizing fuel production processes or sourcing alternative raw materials.7 This approach broadens the range of potential low-carbon fuels and feedstocks considered by the shipping industry.7
• Avoids Undesirable Externalities: A thorough WtW approach considers other externalities beyond GHGs, such as emissions of other atmospheric pollutants, socially undesirable outcomes, or the unsustainable use of scarce resources during fuel production, transport, storage, and use.7
• Incentivizes Cleaner Production: Even for conventional fossil fuels, WtW incentivizes producers to implement cleaner production practices, as these efforts are directly reflected in the overall WtW emissions profile.7
• Protects Against Reputational Risk: By providing comprehensive visibility throughout the supply chain, WtW helps shipping companies avoid accusations of “greenwashing” or deceptive environmental claims as they pursue decarbonization.7

The comprehensive list of benefits associated with WtW collectively points towards a transformative impact on the maritime fuel supply chain. Beyond mere regulatory compliance, WtW analysis enables ship operators to genuinely differentiate themselves as environmentally responsible entities, which can attract green finance and environmentally conscious clients. This implies that WtW is not merely a technical preference but a strategic tool for competitive advantage, fostering innovation and driving the entire fuel production and distribution ecosystem towards cleaner practices. Ultimately, this leads to a more sustainable and resilient maritime industry.

The following table summarizes the key benefits of adopting a Well-to-Wake approach for marine fuels:

3.3 Limitations of a Tank-to-Wake Approach

While seemingly simpler, the Tank-to-Wake (TtW) approach presents significant limitations that hinder genuine decarbonization efforts and can lead to misleading conclusions about environmental performance.

Firstly, as previously discussed, TtW fundamentally misrepresents the total climate and health impacts of shipping fuels by entirely ignoring the upstream emissions associated with their production and transport.8 This narrow focus creates an incomplete and potentially deceptive picture of a fuel’s true environmental footprint.

Secondly, by concentrating solely on tailpipe emissions, TtW offers no incentive for fuel producers to reduce emissions during the extraction, processing, or transportation phases. This effectively absolves upstream actors of their environmental responsibility, shifting the entire burden of decarbonization to the ship operator.

Thirdly, a strict TtW approach would severely limit the range of viable decarbonization options for the industry. It would effectively restrict the maritime sector to only zero-tailpipe emission fuels (e.g., hydrogen, ammonia, batteries), potentially excluding other promising low-carbon alternatives that achieve significant upstream emission reductions but still have some tailpipe emissions.8 This could prematurely sideline fuels like renewable natural gas or renewable methanol, which can offer immediate emission reductions and play a crucial role in the transition phase.8

Finally, under a TtW framework, there would be no regulatory obligation for fuels like ammonia or hydrogen to be derived from renewable feedstocks. The regulatory scope would cease once the fuel is in the tank, meaning that even if a fuel has zero tailpipe emissions, its overall climate impact could still be substantial if produced using highly carbon-intensive methods (e.g., gray hydrogen).8

These limitations of TtW reveal a form of “regulatory myopia.” By narrowly defining the scope of emissions, TtW overlooks crucial opportunities for decarbonization that exist within the broader fuel supply chain. This implies that adhering to a TtW approach would not only impede the achievement of ambitious GHG reduction targets but also stifle innovation in upstream fuel production, ultimately slowing down the broader energy transition necessary for the maritime sector.

4. Feasibility and Justification: Adopting a Well-to-Wake Methodology for the Shipping Industry

The transition to a Well-to-Wake (WtW) methodology for assessing marine fuel emissions is not merely a technical preference but an increasingly urgent imperative for the shipping industry. This section will justify the feasibility and necessity of adopting WtW, considering the evolving regulatory landscape, the strategic advantages it offers for decarbonization, and the practical challenges that must be addressed for successful implementation.

4.1 Regulatory Landscape and IMO’s Evolving Stance

The International Maritime Organization (IMO) has firmly committed to decarbonizing international shipping, as evidenced by the adoption of its ambitious 2023 IMO GHG Strategy. This strategy sets a target of achieving net-zero GHG emissions from international shipping by or around 2050.4 To guide this transition, the strategy includes indicative check-points for significant GHG reductions: at least 20% (striving for 30%) by 2030, and at least 70% (striving for 80%) by 2040, all compared to 2008 levels.4

Crucially, the IMO has already adopted Guidelines on life cycle GHG intensity of marine fuels (LCA Guidelines), which explicitly allow for a Well-to-Wake assessment of GHG emissions.2 Work is actively ongoing to further develop the comprehensive Life Cycle GHG Assessment (LCA) framework.6 The 2023 IMO GHG Strategy outlines “mid-term measures” that include a key technical element: a goal-based marine fuel standard designed to regulate the phased reduction of marine fuel’s GHG intensity.6 This standard is specifically intended to require ships to utilize fuels that emit fewer WtW GHG emissions, driving a complete transition towards zero-emission fuels.4

The IMO has established a clear timeline for the implementation of these mid-term measures. The approval of the draft legal text, known as the “IMO Net-Zero Framework,” was completed in Spring 2025 (MEPC 83). Adoption is slated for an extraordinary MEPC session in Autumn 2025, with expected entry into force 16 months later in 2027.6 Beyond the IMO, regional regulations, such as the EU’s FuelEU Maritime initiative, are also moving to assess fuels based on their lifetime carbon emissions (WtW), further solidifying this global regulatory trend.7

The IMO’s adoption of LCA Guidelines and the explicit integration of WtW into its forthcoming goal-based marine fuel standard signals an undeniable and irreversible regulatory shift. This implies that WtW is rapidly transitioning from a preferred analytical tool to a mandatory compliance framework. For the shipping industry, this means that future fuel procurement, ship design, and operational strategies must align with WtW principles to ensure regulatory compliance, avoid potential penalties, and maintain access to global shipping markets. The convergence with regional regulations like FuelEU Maritime further underscores this imperative, making WtW a non-negotiable aspect of future operations.

The following table outlines the IMO’s 2023 GHG Strategy targets and timeline, emphasizing the integration of the Well-to-Wake concept:

4.2 Strategic Advantages for Decarbonization and Investment

Beyond regulatory compliance, adopting a WtW methodology offers profound strategic advantages for the shipping industry’s decarbonization journey, positioning it for sustainable growth and attracting necessary investment.

WtW enables a robust and equitable comparison of diverse alternative fuels, including renewable e-fuels (such as hydrogen, ammonia, and methanol) and sustainable biofuels.4 This is crucial given the multitude of factors involved in fuel selection, including technological feasibility, safety concerns, fuel availability, economic costs, and overall environmental impacts.5 By providing a comprehensive metric, WtW facilitates informed decision-making in a complex and evolving fuel landscape.

By setting limits on the WtW GHG intensity of fuels, the IMO’s forthcoming GHG Fuel Standard will directly stimulate investments in the production capacity and infrastructure necessary for new, low-carbon fuels.4 This creates a powerful incentive for the entire supply chain—from feedstock producers to fuel distributors—to reduce emissions, rather than placing the entire burden solely on the ship operator.7

Adopting a WtW approach directly aligns the maritime sector’s decarbonization efforts with broader global climate goals, including the Paris Agreement and the aspiration to limit global warming to 1.5°C.4 Achieving the IMO’s ambitious targets necessitates significant reductions in WtW GHG intensity, such as an 18% reduction by 2030 and a 72% reduction by 2040 compared to a 2019 baseline.4 WtW provides the necessary framework to track and verify progress towards these critical global objectives.

Furthermore, WtW unlocks significant economic opportunities. It expands the possibilities for economically reducing carbon intensity, for example, through optimizing fuel production processes or by sourcing alternative raw materials more sustainably.7 It also provides ship operators with greater control over the pricing of low-carbon fuels by offering an accurate and transparent representation of their true carbon intensity, which can be factored into carbon pricing mechanisms.7

The strategic advantages of WtW extend beyond mere compliance; they position the methodology as a catalyst for systemic innovation and a magnet for green finance. By providing a transparent and comprehensive measure of environmental performance, WtW allows investors to confidently back truly sustainable projects across the entire fuel value chain. This implies that the adoption of WtW will not only reshape fuel markets but also accelerate the development and deployment of cutting-edge technologies and infrastructure necessary for the maritime sector to achieve net-zero emissions, transforming it into a leader in the global energy transition.

4.3 Practical Considerations and Challenges for Implementation

While the strategic imperative for Well-to-Wake (WtW) is clear, its practical implementation presents several significant considerations and challenges that the shipping industry must address collaboratively.

Firstly, performing an accurate WtW LCA requires extensive and granular data collection across highly complex supply chains, from the initial feedstock production to the final use onboard the vessel.1 This complexity is further compounded by the existence of 128 different fuel pathways specified by the IMO’s LCA Guidelines, each with its unique characteristics and data requirements.2

Secondly, the Fuel Lifecycle Label (FLL), which conveys WtW information, requires verification and certification by a third party.2 This necessitates the establishment of robust audit trails and potentially new industry standards for data transparency, integrity, and traceability, perhaps even leveraging digital solutions like blockchain.7

Thirdly, “allocation problems” arise when a fuel production process yields more than one product (co-products). Accurately allocating environmental impacts among these co-products can be complex and requires careful methodological consideration.1 Similarly, for biomass-based fuels, the assessment must account for indirect land use change (ILUC) impacts, adding another layer of complexity to the overall environmental footprint.11

Moreover, emissions and other parameters can exhibit variability and uncertainty depending on the specific fuel type, its origin, and its production pathway.5 This inherent variability requires sophisticated modeling and robust data sets to ensure reliable WtW assessments.

From an economic perspective, alternative fuels currently face significant cost premiums, with some studies indicating they can be five times more expensive than conventional heavy fuel oil (HFO).5 This economic disparity represents a substantial barrier to widespread adoption and necessitates supportive policy mechanisms, such as carbon pricing, to bridge the cost gap and make cleaner alternatives economically viable.6

Finally, transitioning to new alternative fuels often demands substantial changes in bunkering infrastructure and onboard safety measures due to differing fuel characteristics.5 For instance, ammonia, while a promising zero-carbon fuel, requires significantly greater volume (5.03 times) and higher weight (2.3 times) for the same energy content compared to marine diesel, which can increase the overall energy consumption of the vessel.5 Despite years of exploration, a lack of consistent evaluation criteria for selecting alternative fuels persists among global shipping companies 5, underscoring the urgent need for widespread understanding and adoption of WtW as the primary assessment standard.

The practical challenges associated with WtW implementation—including data complexity, verification, cost implications, and necessary infrastructure and safety upgrades—highlight that while WtW is the scientifically sound approach, its successful adoption is contingent upon collaborative innovation and robust policy support. This implies that industry stakeholders, technology providers, regulators, and financial institutions must work in concert to develop standardized data platforms, invest in necessary infrastructure, and implement economic mechanisms that bridge the cost gap and de-risk investments in low-carbon fuel pathways. Without this concerted effort, the transition to WtW-compliant operations will be significantly hampered.

5. Conclusion and Recommendations

The imperative for the maritime sector to decarbonize is undeniable, and at the heart of this transformation lies the adoption of a comprehensive and scientifically robust methodology for assessing fuel emissions. Life Cycle Analysis (LCA), specifically the Well-to-Wake (WtW) approach, stands out as the most feasible and necessary methodology to achieve genuine and verifiable greenhouse gas (GHG) reductions.

5.1 Reiteration of WtW as the Most Feasible and Necessary Methodology

WtW moves beyond the inherent limitations of the Tank-to-Wake (TtW) approach by capturing the entire fuel life cycle, from feedstock extraction and production through to onboard consumption. This holistic perspective is crucial because it prevents “burden shifting,” ensuring that emissions are not merely relocated upstream or downstream in the supply chain but are genuinely reduced across the entire value chain. WtW provides an accurate and equitable basis for comparing the diverse array of alternative fuels emerging in the market, allowing for informed decisions that truly contribute to climate goals.

The evolving regulatory landscape, spearheaded by the International Maritime Organization (IMO) and mirrored by regional initiatives like the EU’s FuelEU Maritime, increasingly mandates a WtW assessment for marine fuels. The IMO’s 2023 GHG Strategy, with its ambitious net-zero targets and the forthcoming goal-based marine fuel standard, explicitly integrates WtW as the foundational metric. This makes the adoption of WtW not just an environmental best practice but a non-negotiable compliance imperative for the future of international shipping. While practical challenges exist, the strategic advantages—including driving innovation, attracting green finance, and ensuring alignment with global climate objectives—far outweigh the difficulties, positioning WtW as the indispensable framework for the maritime industry’s decarbonization journey.

5.2 Recommendations for Industry Stakeholders

To navigate the transition to a WtW-centric future and achieve ambitious decarbonization targets, key stakeholders in the maritime industry should consider the following actionable recommendations:

• Invest in WtW Data Systems and Expertise: Shipping companies and fuel suppliers should proactively allocate resources towards developing or acquiring robust data collection, management, and analytical systems capable of performing comprehensive WtW assessments. This includes fostering in-house expertise in LCA methodologies or establishing strategic collaborations with specialized LCA consultants and technology providers.
• Promote Supply Chain Transparency and Collaboration: To ensure the accuracy and verifiability of WtW data, greater transparency and collaboration are essential across the entire fuel supply chain, from feedstock producers to bunkering operations. This may involve implementing digital solutions, such as blockchain-based platforms, to enhance data traceability and integrity throughout the value chain.
• Advocate for Consistent Global WtW Standards: Industry associations and individual companies should actively engage with international regulatory bodies, including the IMO and ISO, to advocate for the development and consistent application of harmonized global WtW standards and methodologies. This will reduce complexity, foster a level playing field, and accelerate industry-wide adoption.
• Integrate WtW into Strategic Planning: WtW analysis should be a fundamental component of all strategic decisions related to fuel procurement, fleet renewal, and infrastructure development. This involves evaluating the true carbon intensity and long-term economic implications—including the impact of carbon pricing mechanisms—of various fuel pathways.
• Support Research and Development: Continued investment in research and development for new low- and zero-carbon fuels and their production pathways is crucial. WtW assessments should guide these R&D efforts, ensuring that innovations are directed towards truly sustainable solutions that deliver genuine life cycle emission reductions.
• Engage with Policy Makers: Active participation in policy discussions is vital to ensure that regulatory frameworks, such as carbon levies, emissions trading schemes, and targeted subsidies, are effectively designed to incentivize the adoption of WtW-compliant fuels and technologies. Such policies are critical for bridging the economic viability gap for cleaner alternatives and accelerating the industry’s green transition.

Works cited

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