Playbook: adopting sustainable aviation & shipping in 90 days

Global sustainable aviation fuel (SAF) production doubled in 2024 to 1.0 million tonnes—yet this represents just 0.3% of total jet fuel consumption, while shipping remains the world's sixth-largest greenhouse gas emitter if counted as a country. For UK-focused product and design teams navigating the hidden trade-offs in transport decarbonization, understanding what's actually working requires moving beyond headline commitments to operational reality. This playbook examines city and utility pilot results that reveal the genuine constraints shaping sustainable aviation and shipping adoption.

Why It Matters

Aviation and maritime shipping present the most challenging decarbonization frontiers in the transport sector. Unlike road transport, where electrification provides a clear pathway, long-haul aviation and oceanic shipping face fundamental constraints: energy density requirements that current battery technology cannot satisfy, infrastructure spanning multiple jurisdictions, and capital stock turnover rates measured in decades rather than years.

The UK occupies a strategic position in this transition. The UK SAF mandate entered force in 2025, requiring fuel suppliers to ensure 2% of jet fuel comes from sustainable sources—creating immediate market demand and triggering price dynamics that reveal true cost structures. The UK's maritime sector, supporting £46 billion in trade annually, faces simultaneous pressure from the International Maritime Organization's 2030 targets and the UK Shipping Office for Reducing Emissions (UK SHORE) initiatives.

For product and design teams, these constraints define the solution space. Carbon intensity reduction must accommodate incumbent infrastructure, permitting realities, and supply chain dependencies. Biomaterial feedstock availability limits SAF production pathways. Resilience requirements—the ability to operate reliably across diverse conditions—constrain technology choices. Biodiversity considerations increasingly shape feedstock sourcing and port development decisions.

The 2025 landscape represents an inflection point: regulatory mandates have converted aspiration to obligation, technology options have multiplied, but the gap between policy ambition and operational capacity remains stark.

Key Concepts

Sustainable Aviation Fuel Pathways

SAF encompasses multiple production technologies. HEFA (Hydrotreated Esters and Fatty Acids) dominates current production at 82-85% of capacity, converting used cooking oils and waste animal fats into jet fuel. Alcohol-to-Jet (AtJ) converts ethanol or methanol to jet fuel, representing approximately 8% of projected 2030 capacity. Power-to-Liquid (PtL) or e-SAF synthesizes fuel from green hydrogen and captured CO2—the ultimate scalable solution but currently at cost premiums up to 12 times conventional jet fuel.

Maritime Alternative Fuels

The maritime fuel transition has consolidated around three primary alternatives. Liquefied Natural Gas (LNG) reduces sulfur and particulate emissions but offers limited greenhouse gas benefits due to methane slip. Methanol has emerged as the leading liquid alternative fuel, with 450+ methanol-capable vessels on water or on order by late 2025. Ammonia and hydrogen represent deeper decarbonization options but require new engine technologies and bunkering infrastructure not yet widely available.

Feedstock and Sustainability Constraints

Both SAF and maritime biofuels face feedstock constraints. EU SAF production in 2024 relied primarily on used cooking oil (81%) and waste animal fats (17%), with 69% of feedstock imported—38% from China alone. This dependence creates supply chain vulnerabilities while raising questions about feedstock authenticity and sustainability verification. Biomaterial competition between aviation, shipping, and other sectors intensifies as mandates drive demand.

Permitting and Infrastructure Dependencies

New fuel production facilities require environmental permits, planning approvals, and infrastructure connections that add years to project timelines. Port infrastructure for alternative fuel bunkering requires similar permitting pathways. The mismatch between policy timelines (mandates effective 2025) and infrastructure timelines (facilities requiring 3-5 years from decision to operation) defines much of the current market stress.

Fuel Type	GHG Reduction vs. Conventional	2024 Cost Premium	Infrastructure Readiness	Scalability Assessment
HEFA SAF	50-80%	2-3x	High	Feedstock-limited
AtJ SAF	65-85%	3-4x	Medium	Scaling potential
e-SAF/PtL	90-99%	8-12x	Low	Unlimited potential
Bio-methanol	65-95%	1.5-2x	Growing	Moderate
Green ammonia	90-99%	2-4x	Emerging	High potential
LNG	10-20%	0.8-1.2x	Established	Transition fuel only

What's Working

UK SAF Mandate Market Creation

The UK's SAF mandate, requiring 2% sustainable fuel in 2025 and scaling to 10% by 2030, has transformed market dynamics. Prior to the mandate, SAF procurement was voluntary and sporadic. Post-mandate, fuel suppliers face compliance obligations that guarantee demand regardless of cost premium. This regulatory certainty has unlocked investment decisions that voluntary commitments could not support. Phillips 66 and other major fuel suppliers have announced UK-targeted SAF production capacity in response.

Methanol-Fueled Vessel Orders Acceleration

The maritime sector has coalesced around methanol as the leading liquid alternative fuel, with over 450 methanol-capable vessels on water or on order by late 2025. Maersk's commitment to methanol-powered container ships—including 19 methanol-capable vessels ordered since 2021—demonstrates major shipping lines' confidence in the pathway. Methanol's advantages include liquid state at ambient temperature (simpler handling than LNG), available dual-fuel engines, and compatibility with both bio-methanol and e-methanol as production scales.

Port Cluster Decarbonization Initiatives

UK ports including Felixstowe, Southampton, and Aberdeen have launched coordinated decarbonization initiatives combining shore power, alternative fuel bunkering infrastructure, and operational efficiency improvements. The Port of Aberdeen's £420 million South Harbour development incorporates hydrogen and ammonia bunkering capacity, positioning the port as a hub for maritime alternative fuels serving North Sea operations. These coordinated investments create the infrastructure foundation that individual vessel investments require.

Aviation Booking and Attribution Systems

Airlines have developed booking systems allowing corporate customers to purchase SAF on their behalf, with verified emissions reductions attributed to the specific customer. This "book and claim" approach addresses SAF's fungibility challenge—the fuel physically blends at airports, making direct tracing impossible. British Airways' SAF program and United Airlines' Eco-Skies Alliance demonstrate viable models for corporate SAF procurement that product teams can integrate into travel management systems.

What's Not Working

SAF Production Scale Versus Mandate Pace

UK SAF production capacity lags mandate requirements, forcing imports that stress already-tight European supply. The 2% mandate in 2025 requires approximately 300 million liters of SAF for UK departing flights—but domestic production capacity remains minimal. This supply-demand mismatch triggered price spikes following mandate implementation, with SAF premiums in EU markets reaching €2,085 per tonne versus €734 for conventional jet fuel. The 10% 2030 mandate will require domestic production capacity that does not exist on current project timelines.

Feedstock Authentication Challenges

The dominance of used cooking oil as SAF feedstock creates fraud risks that undermine sustainability claims. Reports of virgin palm oil mislabeled as waste cooking oil have plagued European biofuel markets. Traceability systems remain inadequate for verifying feedstock origin and sustainability characteristics at scale. For product teams designing corporate travel sustainability programs, these authentication gaps create reputation risks that simple SAF purchasing cannot address.

Maritime Fuel Availability Gaps

Alternative fuel availability remains geographically concentrated, creating operational constraints for vessels adopting new technologies. Methanol bunkering exists at limited ports, requiring voyage planning that accounts for fuel availability rather than just commercial optimization. Ammonia and hydrogen infrastructure is essentially non-existent outside pilot facilities. This infrastructure gap delays fleet transition by vessels that cannot reliably access alternative fuels across their trading patterns.

Permitting Bottlenecks

New SAF production facilities and port alternative fuel infrastructure face multi-year permitting processes that cannot compress to match policy timelines. Environmental impact assessments, air quality permits, safety certifications, and planning approvals each add months to project schedules. The mismatch between political ambition (net-zero commitments) and administrative capacity (permitting throughput) creates implementation bottlenecks that announcements and targets cannot resolve.

Cost Pass-Through Mechanisms

The economics of sustainable transport ultimately require mechanisms to pass higher fuel costs to end users—passengers and shippers. Airlines face competitive pressure limiting fare increases, while shipping's fragmented structure makes coordinated surcharges difficult. The EU Emissions Trading System extension to shipping in 2024 begins creating cost pressure, but carbon prices remain below levels that would drive fuel switching absent mandates.

Key Players

Established Leaders

Neste operates the world's largest SAF production capacity, with refineries in Finland, Singapore, and the Netherlands producing renewable diesel and SAF from waste and residue feedstocks. Their 2024 expansion increased SAF-capable capacity to over 2 million tonnes annually.

Maersk leads maritime decarbonization through its methanol strategy, having ordered 19 methanol-capable vessels since 2021 and actively developing methanol supply chains across its global network.

Rolls-Royce develops and certifies engines compatible with 100% SAF, removing the current 50% blending limit that constrains SAF utilization. Their 2024 testing demonstrated full SAF compatibility across commercial engine families.

Shell operates integrated refining capable of SAF production and maintains extensive marine fuel bunkering networks positioning the company to deliver alternative marine fuels as supply develops.

Emerging Startups

Velocys develops smaller-scale Fischer-Tropsch technology enabling waste-to-fuel production at sites closer to feedstock sources, with UK projects in development targeting domestic SAF production.

Arcadia eFuels pursues e-SAF production in Norway, leveraging abundant hydropower for green hydrogen generation to produce synthetic jet fuel competitive on lifecycle emissions.

Houlder (UK) provides maritime decarbonization engineering services, helping shipowners and ports navigate technical and regulatory complexity in the fuel transition.

ZeroAvia develops hydrogen-electric aviation powertrains for regional aircraft, representing the alternative pathway to SAF for shorter routes where direct hydrogen propulsion becomes practical.

Key Investors & Funders

UK Infrastructure Bank provides financing for sustainable transport infrastructure including SAF production facilities and port alternative fuel systems, with specific mandate to support net-zero transition.

HyNet consortium coordinates hydrogen production and distribution infrastructure development in Northwest England, enabling both industrial and transport applications of low-carbon hydrogen.

The UK Department for Transport administers the £165 million Advanced Fuels Fund supporting domestic SAF production alongside regulatory mandates creating demand.

Breakthrough Energy Ventures has invested in sustainable aviation and maritime decarbonization companies including ZeroAvia, representing patient capital supporting long-development-cycle technologies.

Real-World Examples

Example 1: Heathrow Airport SAF Infrastructure Development

Heathrow Airport, the UK's largest aviation hub, has developed SAF blending and distribution infrastructure to support the UK mandate while building toward higher blend rates. The airport's 2024 investments included hydrant system modifications enabling SAF blending at multiple concentrations, storage capacity for segregated SAF inventory, and monitoring systems verifying blend ratios. Operational lessons demonstrate that existing airport infrastructure can accommodate SAF with targeted modifications—capex rather than fundamental redesign. However, the example also reveals constraints: blending ratios remain limited by airline engine certification, and physical SAF availability at Heathrow depends on import logistics that add cost and complexity.

Example 2: Port of Rotterdam Green Corridor

The Port of Rotterdam established a "Green Corridor" pilot with the Port of Singapore, creating a defined trade lane where vessels commit to progressive decarbonization targets supported by infrastructure at both ends. The corridor approach addresses the chicken-and-egg challenge: vessels hesitate to adopt alternative fuels without bunkering infrastructure, while ports hesitate to build infrastructure without vessel demand. By coordinating both simultaneously on a specific route, the green corridor creates viable transition economics. For UK product teams, the Rotterdam-Singapore model suggests port-to-port partnerships as a structure for designing maritime sustainability programs rather than fleet-wide mandates.

Example 3: British Airways SAF Corporate Program Results

British Airways launched a corporate SAF program allowing business customers to purchase SAF certificates attributed to their travel, with independent verification of emissions reductions. By late 2024, the program had allocated 10 million liters of SAF to corporate customers—modest in absolute terms but demonstrating functional booking and attribution systems. Participating companies report using SAF purchases for Scope 3 emissions reduction in corporate sustainability reporting. The program reveals both potential (corporate willingness to pay premium for verified emissions reductions) and constraints (available SAF volumes limit program scale regardless of demand).

Action Checklist

• Week 1-2: Baseline Assessment — Quantify current aviation and shipping emissions in Scope 3 inventory; identify highest-impact routes and suppliers where intervention offers greatest leverage
• Week 3-4: Regulatory Mapping — Document applicable mandates (UK SAF, FuelEU Maritime, IMO targets) and compliance timelines affecting your organization and transport providers
• Week 5-6: Provider Engagement — Survey current aviation and shipping providers on decarbonization plans; assess SAF and alternative fuel availability on priority routes
• Week 7-8: Pilot Design — Define limited-scope pilot incorporating SAF booking or alternative fuel shipping; establish measurement protocols and success criteria
• Week 9-10: Contract Negotiation — Negotiate SAF or alternative fuel terms with selected providers; address cost allocation, verification requirements, and attribution mechanisms
• Week 11-12: Pilot Launch and Monitoring — Deploy pilot with intensive monitoring; document operational friction, cost impacts, and verification outcomes for scaling decisions

FAQ

Q: How should organizations balance SAF cost premiums against other decarbonization investments? A: SAF cost-effectiveness varies by context. At current prices (2-5x conventional fuel), SAF delivers carbon reductions at $300-600 per tonne CO2e—expensive compared to many operational efficiency measures but potentially competitive with carbon removal for Scope 3 claims. Organizations should prioritize operational efficiency (route optimization, load factors, modal shift where possible) before SAF premium payments. SAF investment makes most sense when Scope 3 aviation emissions are material and reduction through efficiency measures is exhausted.

Q: What role do carbon offsets play alongside SAF and alternative fuels? A: Offsets and SAF address different parts of the emissions challenge. SAF reduces lifecycle emissions from the fuel itself—the "insetting" approach. Offsets compensate for residual emissions that SAF does not eliminate. High-quality offsets (verified carbon removal) can complement SAF programs but should not substitute for actual emissions reduction. For credible net-zero claims, organizations should maximize SAF adoption for flights taken, then address residual emissions through quality offsets.

Q: How reliable are SAF sustainability claims given feedstock authentication concerns? A: Reliability varies by certification and chain of custody. RSB (Roundtable on Sustainable Biomaterials) and ISCC (International Sustainability and Carbon Certification) provide the most rigorous frameworks, though neither eliminates fraud risk entirely. Book-and-claim systems add additional complexity—the SAF physically consumed may differ from the SAF purchased. Organizations should require specific certification standards in SAF contracts and consider third-party verification of claims for material sustainability reporting.

Q: What shipping decarbonization options exist for organizations without fleet ownership? A: Shippers can influence maritime emissions through carrier selection (favoring lines with decarbonization commitments), contract specifications (requiring emissions reporting, incentivizing lower-carbon vessels), route optimization (accepting slower transit for efficiency gains), and green corridor participation (directing freight through decarbonizing trade lanes). The Clean Cargo Working Group provides benchmarking data enabling informed carrier selection. Emissions clauses in freight contracts are emerging but not yet standard.

Q: How do biodiversity considerations affect SAF and maritime fuel choices? A: Feedstock sourcing creates biodiversity trade-offs. SAF from purpose-grown crops risks habitat conversion; SAF from used cooking oil avoids this but faces supply constraints. Maritime biofuels face similar feedstock considerations. Port infrastructure development for alternative fuels requires environmental assessment addressing marine and coastal ecosystems. Organizations should require feedstock sustainability certification (ISCC, RSB) and consider Scope 3+ biodiversity impacts alongside carbon metrics in transport fuel decisions.

Sources

• U.S. Energy Information Administration. "U.S. sustainable aviation fuel production takes off as new capacity comes online." EIA Today in Energy, 2024.
• EASA. "Sustainable Aviation Fuel scale-up, progress and pressure points." European Union Aviation Safety Agency, 2024.
• Global Maritime Forum. "Why 2025 is such an important year for shipping decarbonisation." GMF Publications, 2024.
• DNV. "Maritime Forecast to 2050." DNV AS, 2024.
• IATA. "SAF Production Growth Rate is Slowing Down." International Air Transport Association, December 2024.
• UK Department for Transport. "Jet Zero Strategy: Delivering Net Zero Aviation by 2050." UK Government, 2024.