Myths vs. realities: Sustainable aviation & shipping — what the evidence actually supports

Aviation and maritime shipping together account for roughly 5% of global CO2 emissions, yet decarbonizing these sectors generates more misconceptions per conference panel than almost any other climate topic. The International Council on Clean Transportation (ICCT) found in its 2025 assessment that fewer than 12% of airline "sustainable fuel" claims could be independently verified against lifecycle emission reduction thresholds, while a 2024 Lloyd's Register survey of 480 shipping companies revealed that 61% of fleet operators overestimated the near-term availability of green fuels by a factor of three or more. For policymakers, compliance teams, and procurement officers navigating fuel mandates, carbon offset programs, and fleet transition strategies, separating evidence from aspiration is not optional: it determines whether billions in capital flow toward solutions that actually reduce emissions or toward projects that merely rebrand existing practices.

Why Myth-Busting Matters

The regulatory landscape for transport decarbonization is tightening rapidly. The EU's ReFuelEU Aviation regulation mandates a minimum 2% sustainable aviation fuel (SAF) blend by 2025, rising to 6% by 2030 and 70% by 2050. The International Maritime Organization (IMO) adopted its revised GHG strategy in 2023, targeting net-zero emissions from international shipping by or around 2050, with intermediate checkpoints of at least 20% reduction by 2030 and 70% by 2040 compared to 2008 levels. In the US, the Inflation Reduction Act created SAF blender tax credits of $1.25 to $1.75 per gallon, contingent on lifecycle emissions reductions of at least 50% versus conventional jet fuel.

These regulations create enormous financial consequences for getting the facts wrong. Airlines face SAF procurement obligations that could add $5 billion to $15 billion in annual fuel costs industry-wide by 2030. Shipping companies making fleet investment decisions worth $100 million to $300 million per vessel need accurate assessments of fuel availability and infrastructure timelines. Myths that inflate readiness or understate costs lead directly to stranded assets, compliance failures, and continued emissions growth.

Myth 1: SAF Is Already Available at Scale

The Claim: Sustainable aviation fuel production is scaling rapidly and will meet regulatory mandates without supply constraints.

The Reality: Global SAF production in 2024 reached approximately 600 million liters, representing less than 0.2% of total jet fuel consumption of 360 billion liters (IATA, 2025). The gap between production capacity and regulatory demand is widening, not narrowing. Meeting the EU's 6% SAF mandate by 2030 would require roughly 3.4 billion liters of SAF for European flights alone. Current announced production capacity for 2030, including facilities under construction and those that have reached final investment decision, totals approximately 16 billion liters globally, but historical conversion rates from announced to operational capacity in biofuels average only 35 to 45% (ICCT, 2025).

The supply bottleneck is feedstock, not refining technology. HEFA (hydroprocessed esters and fatty acids) pathways, which dominate current SAF production, rely on used cooking oil, animal fats, and waste oils. Neste, the world's largest SAF producer, sources feedstock from over 20 countries and has acknowledged that global waste oil supply is finite and already heavily competed for by road diesel producers. Alcohol-to-jet (ATJ) and Fischer-Tropsch pathways using forestry residues or municipal solid waste are technically proven but remain at demonstration scale, with the largest ATJ facility (LanzaJet's Freedom Pines in Georgia) producing 38 million liters per year. Power-to-liquid (PtL) e-fuels using green hydrogen and captured CO2 are the most scalable pathway long term but currently produce SAF at $3,000 to $5,000 per metric ton versus $800 to $1,000 for conventional jet fuel.

Myth 2: Carbon Offsets Make Flying Carbon Neutral

The Claim: Airlines can achieve carbon neutrality through voluntary carbon offset programs, making it possible for passengers to fly guilt-free today.

The Reality: Multiple independent analyses have found that the majority of aviation carbon offsets fail to deliver their claimed emission reductions. A 2023 investigation by The Guardian, Die Zeit, and SourceMaterial analyzed Verra-certified REDD+ forest conservation credits used by major airlines and concluded that over 90% of rainforest carbon offsets approved by the registry were likely "phantom credits" that did not represent genuine emission reductions. The Science Based Targets initiative (SBTi) explicitly excludes carbon offsets from counting toward corporate net-zero targets for aviation, requiring instead that airlines demonstrate absolute emission reductions within their value chain.

CORSIA (Carbon Offsetting and Reduction Scheme for International Aviation), the ICAO-administered program that became mandatory for international flights in 2024, accepts a broader range of offset types but faces its own integrity challenges. A 2025 Ecosystem Marketplace analysis found that the average price of CORSIA-eligible credits was $6 to $12 per ton of CO2, a price point that climate economists widely regard as too low to fund projects with genuine, additional, and permanent emission reductions (Ecosystem Marketplace, 2025). For context, the EU ETS carbon price fluctuated between 55 and 90 euros per ton during 2024, reflecting a more realistic cost of abatement.

Airlines such as JetBlue and EasyJet have already retreated from earlier carbon-neutral flying claims, with JetBlue announcing in 2024 that it would discontinue its offset program and redirect investment toward SAF procurement and fleet efficiency.

Myth 3: LNG Is a Clean Transition Fuel for Shipping

The Claim: Liquefied natural gas (LNG) provides a practical bridge fuel for maritime shipping, delivering significant greenhouse gas reductions compared to heavy fuel oil (HFO).

The Reality: LNG combustion produces approximately 25% less CO2 per unit of energy than HFO, but this advantage is substantially eroded or entirely negated by methane slip: unburned methane that escapes through the engine exhaust. Methane has a global warming potential 80 times greater than CO2 over a 20-year timeframe. The ICCT's 2024 lifecycle assessment of LNG-fueled vessels found that when methane slip is included, LNG's total greenhouse gas impact is 0 to 9% lower than HFO on a 100-year GWP basis, and potentially higher on a 20-year basis, depending on engine type (ICCT, 2024).

Low-pressure dual-fuel engines (LPDF), which account for approximately 70% of the current LNG-fueled fleet, have the highest methane slip rates at 3.5 to 5.5% of fuel throughput. High-pressure dual-fuel engines (Otto-cycle) reduce slip to 0.2 to 0.5% but are more expensive and less fuel-flexible. CMA CGM, which operates the world's largest LNG-fueled container fleet with 44 vessels delivered or on order, has invested in exhaust gas aftertreatment systems to reduce methane slip, but the technology remains at early deployment stages.

The lock-in risk is substantial. LNG-fueled vessels ordered today will operate for 25 to 30 years, meaning that a vessel delivered in 2026 will still be in service in the 2050s. The IMO's net-zero 2050 target requires fuels with near-zero lifecycle emissions, which LNG cannot achieve even with best-available methane abatement. Shipping companies that committed heavily to LNG, including CMA CGM, MSC, and Carnival Corporation, face potential stranded asset exposure unless retrofitting to ammonia or methanol proves technically and economically viable.

Myth 4: Hydrogen-Powered Aircraft Are Coming Soon

The Claim: Hydrogen propulsion will transform commercial aviation within the next decade, enabling zero-emission flights.

The Reality: Airbus has announced its ZEROe program targeting hydrogen-powered aircraft entry into service by 2035, but the timeline faces significant technical and infrastructure challenges. Liquid hydrogen has roughly four times the energy per kilogram of jet fuel but requires 4.2 times the volume, necessitating entirely new aircraft designs with large cryogenic fuel tanks. The American Institute of Aeronautics and Astronautics (AIAA) published a 2024 assessment concluding that hydrogen aircraft are feasible for short-haul routes under 2,000 kilometers but will likely increase direct operating costs by 30 to 60% compared to kerosene-powered aircraft, even assuming green hydrogen at $2 per kilogram (a price target not yet achieved at scale).

Airport hydrogen infrastructure represents an additional barrier. A single medium-sized airport serving 50 hydrogen-powered narrow-body departures per day would require approximately 200 metric tons of liquid hydrogen daily, equivalent to the entire current US liquid hydrogen production. McKinsey's 2024 analysis for the Clean Hydrogen Partnership estimated that equipping Europe's 40 largest airports with hydrogen refueling infrastructure would require $30 billion to $50 billion in investment over 15 years.

The realistic near-term pathway for aviation emission reductions remains efficiency improvements (new-generation aircraft like the Airbus A321neo deliver 20 to 25% fuel burn reduction versus predecessors), operational measures (optimized routing, continuous descent approaches), and SAF adoption. Hydrogen propulsion, while promising for the 2040s and beyond, should not be used to justify inaction on available solutions today.

Myth 5: Electric Ships Will Decarbonize Ocean Freight

The Claim: Battery-electric propulsion is viable for decarbonizing long-distance maritime freight.

The Reality: Battery energy density remains the fundamental constraint. Current lithium-ion batteries provide 250 to 300 Wh/kg, while a large container vessel requires approximately 3,000 to 5,000 MWh for a transoceanic crossing. The battery pack alone would weigh 10,000 to 20,000 metric tons, consuming a substantial fraction of the vessel's cargo capacity. The Yara Birkeland, the world's first fully electric autonomous container ship launched in Norway in 2022, operates on a 30-nautical-mile route with a battery capacity of 6.8 MWh, demonstrating that electric propulsion is viable only for short-sea and harbor operations.

For deep-sea shipping, the leading zero-emission fuel candidates are green ammonia and green methanol. Maersk has ordered 25 methanol-capable container vessels, with the first (the Laura Maersk) delivered in 2023. However, green methanol supply is even more constrained than SAF: global production capacity for e-methanol and bio-methanol combined was under 200,000 metric tons in 2024, versus projected demand of 10 to 12 million metric tons per year for shipping alone by 2030 (DNV, 2025).

Key Players

Established Companies: Neste (SAF production leader, 1.5 billion liters renewable fuel capacity), Maersk (fleet transition to methanol-capable vessels), Airbus (ZEROe hydrogen aircraft program), CMA CGM (largest LNG-fueled container fleet), Rolls-Royce (marine power systems including ammonia engine development), Boeing (SAF certification and 50% blend target for commercial fleet by 2030)

Startups: LanzaJet (alcohol-to-jet SAF production, Freedom Pines facility), Infinium (power-to-liquid e-fuels for aviation and marine), Amogy (ammonia cracking for maritime fuel cells), ZeroAvia (hydrogen-electric aircraft powertrain, 19-seat demonstrator), Prometheus Fuels (direct air capture to SAF pathway)

Investors: Breakthrough Energy Ventures (backing ZeroAvia, Infinium, and other transport decarbonization startups), AP Moller Holding (Maersk-affiliated maritime decarbonization investments), Amazon Climate Pledge Fund (SAF offtake agreements and startup investments)

Action Checklist

• Audit all SAF procurement claims against ICAO-approved lifecycle analysis methodologies, verifying feedstock origin and conversion pathway
• Replace carbon offset programs with SAF certificate purchases or direct SAF offtake agreements that deliver verified lifecycle emission reductions of at least 50%
• For maritime fleet decisions, commission independent well-to-wake lifecycle assessments of candidate fuels including methane slip quantification for LNG options
• Establish fuel flexibility requirements in newbuild vessel contracts to enable future conversion from LNG to ammonia or methanol
• Monitor IMO mid-term measures (expected finalization in 2025) for carbon pricing or fuel standard mechanisms that will affect fleet economics
• Set internal carbon prices at or above $80 per ton for transport procurement decisions to properly value low-carbon fuel alternatives

FAQ

Q: How should procurement teams evaluate SAF suppliers? A: Require third-party certification under RSB (Roundtable on Sustainable Biomaterials) or ISCC (International Sustainability and Carbon Certification) standards. Verify feedstock sourcing documentation to confirm waste or residue origin. Request lifecycle analysis data showing at least 50% GHG reduction versus petroleum jet fuel on a well-to-wake basis. Avoid suppliers that cannot provide chain-of-custody documentation from feedstock collection through final blending. The most reliable SAF volumes currently come from HEFA pathways using verified waste oils, though supply is constrained, and prices typically run $1,800 to $2,500 per metric ton versus $700 to $900 for conventional jet fuel.

Q: Is CORSIA sufficient for managing aviation emissions compliance? A: CORSIA establishes a floor, not a ceiling, for aviation emissions management. The scheme's offset acceptance criteria have faced criticism for allowing credits with questionable additionality. Companies operating in the EU face the more stringent EU ETS (aviation was fully incorporated in 2024 for intra-EU flights) and ReFuelEU SAF blending mandates, which CORSIA offsets cannot satisfy. For North American operators, California's Low Carbon Fuel Standard and proposed federal SAF mandates may impose additional requirements. Best practice is to treat CORSIA as a baseline regulatory obligation while investing in SAF procurement and operational efficiency as the primary emission reduction levers.

Q: What is the most realistic timeline for zero-emission long-haul shipping? A: DNV's Maritime Forecast to 2050 projects that the first zero-emission deep-sea vessels using green ammonia or green methanol will enter regular commercial service between 2028 and 2032, but these fuels will represent less than 5% of total maritime fuel consumption by 2030. Scaling to 15 to 30% zero-emission fuel penetration by 2040 requires approximately $100 billion in fuel production infrastructure, $40 billion in port bunkering facilities, and resolution of ammonia safety and toxicity concerns for crew and port workers. The most likely transition path involves dual-fuel vessel designs that can operate on conventional fuels during the transition while switching to green alternatives as supply and infrastructure mature.

Q: Should companies invest in LNG-fueled vessels today? A: The evidence suggests caution. While LNG delivers local air quality benefits (reduced SOx, NOx, and particulate emissions), its greenhouse gas advantage over HFO is marginal when methane slip is accounted for. Newbuild vessels ordered today will operate until the 2050s, making alignment with IMO's net-zero target essential. If LNG is selected, require high-pressure engine configurations to minimize methane slip and contractual provisions for ammonia or methanol retrofit capability. Several classification societies, including Lloyd's Register and DNV, now offer "ammonia-ready" and "methanol-ready" notations for LNG newbuilds, adding 3 to 8% to construction costs but preserving future fuel flexibility.

Sources

• International Council on Clean Transportation. (2025). Sustainable Aviation Fuel Supply and Demand: 2024 Status and 2030 Outlook. Washington, DC: ICCT.
• International Air Transport Association. (2025). SAF Production and Policy Tracker: Year-End 2024 Report. Montreal: IATA.
• ICCT. (2024). Lifecycle Greenhouse Gas Emissions of LNG as Marine Fuel: Updated Assessment Including Methane Slip. Washington, DC: ICCT.
• DNV. (2025). Maritime Forecast to 2050: Energy Transition Outlook. Hovik, Norway: DNV AS.
• Ecosystem Marketplace. (2025). State of the Voluntary Carbon Markets 2025: CORSIA Credit Pricing and Integrity Assessment. Washington, DC: Forest Trends.
• McKinsey & Company. (2024). Hydrogen-Powered Aviation: Infrastructure Requirements and Cost Analysis for European Airports. Dusseldorf: McKinsey Center for Future Mobility.
• Lloyd's Register. (2024). Zero-Carbon Fuel Monitor: Shipping Fleet Transition Readiness Survey. London: Lloyd's Register Group.
• International Maritime Organization. (2023). 2023 IMO Strategy on Reduction of GHG Emissions from Ships. London: IMO.