The rapid advancement of synthetic fuel technologies has sparked an urgent question across the energy sector: does the emergence of e-fuels and power-to-liquid processes signal the beginning of the end for biodiesel’s hard-won position in sustainable transport? After two decades of infrastructure investment, policy support, and market development, biodiesel producers and their stakeholders are watching synthetic fuel pilot projects multiply across Europe with understandable concern. Yet the reality emerging from technical analysis, economic modelling, and policy signals suggests something more nuanced than simple displacement. Rather than witnessing a straightforward competition where one technology vanquishes another, we are observing a fundamental reshaping of roles where biodiesel and synthetic fuels may ultimately occupy distinct and complementary niches in the decarbonised transport landscape. The question is not whether biodiesel survives, but rather how its function evolves as synthetic fuels scale from laboratory curiosity to industrial reality.
Understanding the Two Pathways to Low-Carbon Liquid Fuels
Biodiesel: The Established Biological Route
Biodiesel represents the mature face of renewable liquid fuels, produced through the transesterification of organic feedstocks ranging from purpose-grown crops like rapeseed to waste cooking oils and increasingly sophisticated algae cultivation systems. The chemical process yields fatty acid methyl esters that closely mimic the properties of conventional diesel, allowing biodiesel to integrate seamlessly into existing fuel infrastructure when blended at appropriate ratios. This compatibility has proven transformative across European markets, where biodiesel mandates have driven steady growth in production capacity and consumption. The UK’s Renewable Transport Fuel Obligation, for instance, has established biodiesel as a routine component of the diesel supply chain, with B7 blends now standard at forecourts nationwide. When sourced from genuine waste streams or sustainably managed feedstocks, biodiesel delivers impressive greenhouse gas reductions compared to fossil diesel, often exceeding 80 per cent lifecycle carbon savings. Current UK production capacity stands at roughly 200,000 tonnes annually, whilst imports supplement domestic supply to meet growing demand.
Synthetic Fuels: Chemistry’s Industrial Promise
Synthetic fuels approach decarbonisation from an entirely different angle, using industrial chemistry rather than biological processes to create liquid hydrocarbons. The power-to-liquid pathway combines green hydrogen, produced via electrolysis using renewable electricity, with captured carbon dioxide to synthesise hydrocarbon chains through Fischer-Tropsch or similar processes. This chemical route offers a tantalising prospect: creating fuels that are molecularly identical to their fossil counterparts, functioning as perfect drop-in replacements requiring absolutely no engine modifications or infrastructure adaptations. For sectors where even minor fuel property variations create certification nightmares, this chemical fidelity represents a decisive advantage. However, synthetic fuel production today remains largely confined to demonstration plants and pilot facilities. The Norsk e-Fuel project in Norway and the Haru Oni facility in Chile represent the current state of the art, producing thousands rather than millions of tonnes annually. The technological readiness exists, but commercial-scale deployment faces formidable economic and infrastructural hurdles that will take years, perhaps decades, to fully overcome.
Where Synthetic Fuel Development Changes the Competitive Landscape
The Aviation and Maritime Imperative
The development trajectory of synthetic fuels is being powerfully shaped by the desperate needs of aviation and shipping, sectors where biodiesel faces inherent technical limitations that no amount of research can fully overcome. Commercial aviation demands exceptional energy density and precise fuel specifications to ensure safety across extreme temperature and pressure variations encountered at altitude. Jet A-1 specifications leave little room for the property variations inherent in biological feedstocks. Whilst biojet fuels exist and are certified for blending, they face severe feedstock constraints that make scaling to meet global aviation demand practically impossible without competing directly with food production. Synthetic kerosene, by contrast, can theoretically be manufactured in unlimited quantities provided sufficient renewable electricity and carbon feedstock exist. This has led major airlines and aircraft manufacturers to place substantial bets on synthetic aviation fuel as the primary pathway to net zero flying. Similarly, the maritime sector’s requirement for fuels that perform reliably across diverse global bunkering locations and extreme marine environments tilts the balance towards synthetic marine fuels that can slot into existing global supply chains without modification.
Feedstock Competition and Land Use Concerns
Synthetic fuels offer a conceptually elegant answer to biodiesel’s most persistent vulnerability: the criticism around agricultural land use and food security. Even when biodiesel is produced from waste oils or grown on marginal land, the scale required to meaningfully decarbonise transport inevitably raises questions about competing land uses and indirect effects on global agriculture. Synthetic fuel production sidesteps this entire debate by relying on inputs that need not compete with food production. The primary requirements are renewable electricity, water for electrolysis, and a source of carbon dioxide, whether captured directly from the air or from industrial processes. This gives synthetic fuels a theoretical scalability advantage that biodiesel cannot match through biological pathways alone. However, this theoretical promise must be tempered against current realities. The renewable electricity requirements for large-scale synthetic fuel production are staggering, potentially competing with direct electrification priorities. The efficiency of converting renewable electricity to liquid fuel then back to mechanical energy is considerably lower than using that same electricity to directly charge batteries.
Economic and Infrastructural Realities Reshaping Roles
The Cost Trajectory Question
The economics of fuel production will ultimately determine which technologies thrive and which struggle to maintain market share. Biodiesel has achieved remarkable cost reductions over the past two decades, reaching price points that are competitive with fossil diesel in some markets, particularly when policy support mechanisms are factored in. Synthetic fuels, conversely, remain prohibitively expensive for most applications, currently costing three to five times more than conventional fuels even under optimistic scenarios. The pathway to cost parity relies heavily on two factors: dramatic reductions in renewable electricity costs and the learning curve benefits that come with manufacturing scale. Renewable electricity prices have indeed fallen dramatically, and further reductions seem plausible. Yet the fundamental thermodynamic inefficiencies of the power-to-liquid process mean synthetic fuels will likely always carry an energy cost penalty compared to direct electricity use. For biodiesel, the question becomes whether its current cost advantage can be maintained as sustainable feedstock sources become increasingly competed for, and whether policy frameworks like the RTFO will continue to provide stable support as synthetic alternatives emerge. The realistic timeline for synthetic fuel cost competitiveness probably extends into the 2030s, giving biodiesel a crucial window to cement its position in defensible market segments.
Infrastructure Lock-In and Transition Pathways
Biodiesel enjoys a substantial first-mover advantage in having established distribution networks, storage facilities, and engine compatibility across millions of vehicles already on the road. This infrastructure lock-in represents significant sunk capital that creates inertia favouring continued biodiesel use, particularly in road transport where the existing diesel fleet will persist for decades. Paradoxically, however, synthetic fuels’ perfect chemical compatibility with fossil infrastructure may actually erode this advantage. Because synthetic diesel can use precisely the same pipelines, storage tanks, and engines as conventional diesel, it faces no technical barriers to displacement once economics become favourable. This removes the compatibility moat that biodiesel had partially constructed, where switching costs and technical modifications created barriers to competitive entry. Investment decisions in the 2020s must therefore account for this asymmetry: biodiesel infrastructure investments face potential stranding if synthetic fuels achieve cost parity, whilst synthetic fuel infrastructure can theoretically serve multiple fuel types during the transition period.
Policy and Market Signals in the UK and European Context
Regulatory Frameworks and Their Evolution
UK and European policy architecture is simultaneously supporting both biodiesel and synthetic fuels, but with notably different emphases and timescales that reveal strategic priorities. The Renewable Energy Directive’s sustainability criteria have created a framework that continues to underpin biodiesel markets, whilst the UK’s Jet Zero strategy explicitly identifies synthetic aviation fuel as a cornerstone of aviation decarbonisation. Government research funding flows tell a revealing story, with substantial public investment directed towards synthetic fuel research and demonstration projects, whilst biodiesel receives primary support through operational mechanisms like blend mandates rather than innovation funding. This pattern suggests policymakers view biodiesel as a mature technology requiring market support during deployment, whilst synthetic fuels represent a frontier requiring public investment to overcome commercialisation barriers. The evolution of these frameworks will be critical in determining market outcomes, particularly as the EU considers how to structure support mechanisms that avoid picking winners whilst still driving decarbonisation at the pace required by climate commitments.
The Carbon Accounting Conundrum
The methodological intricacies of lifecycle carbon accounting create subtle but consequential differences in how biodiesel and synthetic fuels are perceived and valued within regulatory frameworks. Biodiesel faces stringent scrutiny around indirect land use change, where even waste-based feedstocks can trigger accounting penalties if their diversion from other uses creates knock-on effects elsewhere in the economy. Synthetic fuels, meanwhile, rely heavily on assumptions about the carbon capture processes that supply their carbon feedstock and the renewable credentials of their electricity input. If synthetic fuels are produced using grid electricity in regions with significant fossil generation, their carbon benefits evaporate entirely. These accounting frameworks are not merely technical exercises but rather shape market access and economic viability through mechanisms like the RTFO’s carbon intensity thresholds. The tightening of these standards will likely favour genuinely low-carbon pathways regardless of technology, but the devil resides in methodological details that can advantage one approach over another.
The Emerging Division of Labour in Decarbonised Transport
Road Transport: Biodiesel’s Defensive Territory
For heavy road freight, biodiesel retains compelling advantages during what will inevitably be an extended transition period before full electrification or hydrogen adoption becomes practical for long-haul trucking. The existing diesel engine fleet, particularly heavy goods vehicles and buses, represents a vast installed base that will operate for decades. Biodiesel offers the most cost-effective pathway to immediately reduce emissions from these existing assets without requiring vehicle replacement or fuelling infrastructure overhaul. The economics strongly favour biodiesel in this segment, where its current cost advantage and proven supply chains make it the pragmatic near-term solution even as synthetic fuels capture research attention and headline coverage. Fleet operators making procurement decisions today face a clear choice: deploy biodiesel blends now at manageable cost, or wait for synthetic fuels that may not achieve price parity until their vehicles are ready for retirement anyway. This practical reality creates a defensible position for biodiesel in road transport, particularly in the UK market where diesel remains dominant in the commercial vehicle segment.
Aviation and Shipping: Synthetic Fuels’ Natural Domain
Conversely, the aviation and maritime sectors are increasingly coalescing around synthetic fuels as their primary decarbonisation pathway, driven by technical specifications and operational requirements that favour chemical precision over biological variability. Airlines operate within tightly regulated fuel standards enforced by international safety authorities, making the drop-in compatibility of synthetic kerosene immensely valuable. The global nature of aviation, with aircraft refuelling across dozens of jurisdictions during their service lives, creates powerful advantages for fuels that can integrate seamlessly into existing international supply chains without requiring harmonised technical standards for novel fuel blends. Shipping faces similar constraints, with vessels bunkering at ports worldwide where fuel quality and compatibility must be absolutely assured. The major players in these industries, from aircraft manufacturers to shipping companies, are directing their long-term planning and investment towards synthetic fuel infrastructure, effectively conceding the biodiesel pathway to road transport applications.
Implications for Energy Consultants and Industry Stakeholders
The picture emerging from this analysis suggests that synthetic fuel development is not eliminating biodiesel’s role in transport decarbonisation but rather refining and focusing it. Instead of a winner-takes-all competition, we are witnessing the emergence of a division of labour determined by sector-specific economics, technical requirements, and feedstock realities. Biodiesel appears well positioned to dominate the near-to-medium term road transport sector, where its cost advantages and compatibility with existing vehicle fleets create a strong defensive position. Synthetic fuels, meanwhile, are carving out territory in aviation and maritime applications where their technical properties and scalability potential justify the current cost premium and the substantial public investment required to bring them to commercial scale.
For energy consultants advising clients on investment decisions and strategic positioning, this division of labour carries important implications. Biodiesel investments should be evaluated with a clear-eyed recognition that the technology’s long-term future lies in specific applications rather than universal deployment. The window for establishing profitable biodiesel operations in road transport may be measured in decades, but planning horizons should account for eventual displacement by either electrification or synthetic alternatives as costs evolve. Conversely, synthetic fuel ventures require patient capital and realistic timelines, with commercial viability likely arriving first in high-value applications like aviation before expanding to other sectors. Policy advocacy should recognise that both pathways merit support through distinct mechanisms, with biodiesel requiring stable operational frameworks and synthetic fuels needing innovation funding and demonstration project support. The most sophisticated market participants will position themselves to participate in both pathways, recognising that the decarbonised transport system of 2050 will likely draw upon multiple fuel sources deployed strategically across different applications. Biodiesel’s role is being refined and focused, not eliminated, and the opportunities for those who correctly anticipate these evolving positions remain substantial.




