Synthetic fuel: Types and applications in sustainable mobility

The production of synthetic fuel by thermochemical and electrochemical methods has succeeded in generating hydrocarbons with carbon-neutral potential, compatible with internal combustion engines. This technology facilitates an immediate energy transition without the need to adapt the existing infrastructure; in addition, they are a renewable option that boosts the transportation economy by allowing operational continuity with a smaller environmental footprint.

In the context of sustainable mobility, synthetic fuels are a technical way of operational transition without engine redesign or logistical changes. Information on the origin, composition and applications is significant in assessing the feasibility of the progressive substitution of conventional fossil fuels in real transportation scenarios.

Synthetic fuels: Definition and function

Also known as synfuels, these are artificially produced liquid or gaseous fuels. Unlike fossil fuels, their origin is not in geological deposits, but in alternative raw materials such as captured carbon dioxide (CO₂) and hydrogen, preferably of renewable origin; their great advantage is that they replicate the physicochemical properties of conventional fuels, but with considerably less climate impact.

The function of synthetic fuel is to act as a carbon-neutral energy carrier, replacing petroleum derivatives without compromising energy density, operational stability, thermal efficiency, technological compatibility or autonomy under demanding conditions.

Where does synthetic fuel come from?

Synthetic fuels are produced from synthesis gas (syngas), a mixture of carbon monoxide (CO) and hydrogen (H₂), obtained from biomass, natural gas, coal or by directly capturing atmospheric CO₂. This syngas is converted to liquid hydrocarbons through processes such as Fischer-Tropsch synthesis, where CO and H₂ react catalytically to form long hydrocarbon chains.

As an alternative, electro-fuels (e-fuels) are obtained through Power-to-X (PtX) technology, combining green hydrogen (produced by electrolysis using renewable energy) with captured CO₂, for the formation of compounds, such as e-gasoline, e-diesel or e-kerosene, with carbon neutrality potential. The use of these technologies from the environmental point of view is very important because it allows the reuse of industrial or environmental emissions, favoring the technical closure of the carbon cycle and avoiding the use of fossil resources.

The video provided, entitled “ENEOS Group Synthetic Fuel Initiatives for Carbon-Neutrality”, presents the ENEOS Group’s initiatives in the development of synthetic fuel production technologies as part of its commitment to carbon neutrality. It details the research and development efforts the company is undertaking to create sustainable alternatives to fossil fuels, highlighting the importance of these advances in the global energy transition.

Types of synthetic fuels and their application in mobility

Synthetic fuels comprise a group of products synthesized to directly substitute fossil hydrocarbons, with specific applications in various transportation sectors. Among the best known are:

1. Synthetic gasoline (e-gasoline): produced by Fischer-Tropsch synthesis or MTG (methanol to gasoline) conversion, this gasoline has a high octane rating and is free of toxic compounds such as sulfur or benzene, it is suitable in applications for light urban vehicles.

2. Synthetic diesel and HVO: Synthetic diesel (obtained from gas-to-liquid (GTL) or biomass-to-liquid (BTL)) is produced from natural gas or biomass by Fischer-Tropsch synthesis. In contrast, HVO (hydrotreated vegetable oil) is made from used oils or animal fats. Both synthetic fuels offer operational stability, high thermal efficiency and significant reductions in harmful emissions.

3. Synthetic kerosene: E-kerosene is part of the Sustainable Aviation Fuels (SAF) category, critical for flight decarbonization; this is produced by Power-to-Liquid (PtL) pathways that combine CO₂ with green hydrogen. It complies with ASTM D7566, being suitable for commercial aviation; due to its high energy density, it is used for long-haul flights.

4. E-methane (Synthetic Natural Gas): Also known as synthetic methane, it is obtained through the catalytic methanation of CO₂ with renewable hydrogen. It can be injected into natural gas networks or used in urban transportation with CNG vehicles, facilitating a direct substitution of fossil gas.

5. E-methanol and DME: Synthetic methanol and dimethyl ether (DME) are liquids produced from syngas or direct reaction of CO₂ with hydrogen, used in maritime and land transportation; companies such as Maersk have signed e-methanol supply agreements as an alternative to decarbonize commercial routes, with vessels such as the Ane Maersk already operating using this fuel.

Sectoral applications

• Aviation: e-kerosene and synthetic gasoline for regional and commercial flights.
• Maritime: e-methanol and DME as clean options versus fuel oil.
• Heavy transport: synthetic diesel and HVO as drop-in fuels.
• Urban: CNG and e-gasoline compatible with light vehicles.

Impact of synthetic fuels on transportation

Emission reduction and decarbonization: Their implementation in sectors where electrification is unfeasible makes it possible to mitigate greenhouse gas emissions. By capturing and reusing CO₂, they offer a neutral carbon balance if the CO₂ eliminated is equivalent to that emitted in combustion and if the hydrogen used is of renewable origin, thus closing the carbon cycle in logistics chains with high energy demand.

Strategic complement in the energy transition: based on the use of thermal engines and compatibility with the existing energy infrastructure, they constitute a transitional and scalable solution to the technological, economic and logistical restrictions still presented by electric and hydrogen-powered mobility.

Additional operational advantages

• Carbon circularity: they make it possible to close the emissions cycle by reusing CO₂.
• Energy security: they can be produced locally from renewable sources.
• Lower environmental footprint: their sulfur- and aromatic-free composition improves urban air quality.
• Their implementation promotes regenerative cycles that strengthen the link between sustainability and industrial performance.

Synthetic fuels for internal combustion engines

Synfuels match or exceed the energy density of fossil fuels, reaching up to 44 MJ/kg. This characteristic ensures optimum levels of autonomy in heavy transport and long-distance applications, making it possible to maintain operating efficiency without modifying existing mechanical systems or redesigning engine thermodynamic parameters; their thermal stability and compatibility with current technologies reinforce their viability as a direct substitute for traditional hydrocarbons. 

From the point of view of emissions, carbon-neutral fuels show advantages over conventional fuels; their controlled synthesis process significantly reduces the presence of aromatic and sulfur compounds, reducing the generation of particulate matter and nitrogen oxides (NOx) during combustion. 

In addition, the carbon dioxide emitted can be neutralized by reusing it in the production cycle, technically closing the carbon cycle and improving the environmental profile of transportation based on internal combustion engines.

Sustainable fuel solutions for mobility

Synthetic fuels offer substantial advantages in energy-intensive sectors such as aviation, heavy land transport and shipping, where electrification faces technical and logistical barriers. Their integration into existing engines makes it possible to reduce emissions without affecting range or compromising operating efficiency.

Unlike batteries, which are limited by capacity and charging time, or hydrogen, which requires cryogenic storage and specialized infrastructure, synfuels are an immediate, flexible option that is compatible with conventional thermal platforms.

In this context, synthetic fuels are consolidating as a complementary solution within the hybrid energy ecosystem. Their adoption does not require deep technological reconversion and promotes regenerative cycles that integrate sustainability and operational continuity, while facilitating decarbonization without sacrificing performance or logistical capacity, configuring a functional path towards operationally sustainable mobility.

Synthetic fuels market

The global synthetic fuels market, valued at approximately USD 8.6 billion in 2024, is projected to reach nearly USD 34.7 billion by 2033, at a compound annual growth rate (CAGR) of 16.7% between 2025 and 2033. This projected growth responds to the need for logistics solutions that scale without compromising energy autonomy.

The market is segmented by type of production: Fischer-Tropsch synthesis, advanced biofuels and coal-to-liquid (CTL) processes. Applications include commercial aviation, heavy industry, shipping and the automotive sector, where their high energy density and compatibility with existing installations facilitate the transition to sustainable energy solutions.

Major manufacturers include multinationals such as Shell, ExxonMobil, Sasol, Chevron, BP and TotalEnergies, along with technology companies such as Neste, Velocys, Synhelion, LanzaTech and Fulcrum BioEnergy. Also participating are state and chemical sector players such as Indian Oil Corporation, Syngenta Group, PetroChina and L’Air Liquide, which are leading the development of industrial facilities, carbon capture integration and Power-to-Liquid (PtL) technologies.

Energy transition driven by synthetic fuels

Due to their high energy density, technical scalability and carbon neutrality, synfuels act as a bridging solution in the energy transition; their manufacture from renewable hydrogen and captured CO₂ allows progressive implementation without the need for technological reconversion, positioning them as immediate allies in industrial decarbonization strategies.

In addition to facilitating the operational continuity of logistics sectors, they allow decoupling mobility from the direct use of fossil sources, favoring energy flexibility and diversification of the fuel mix. Their compatibility with existing logistics chains reduces the barriers to their implementation.

Technological advances and industrial initiatives

Current technological developments integrate advanced electrolysis with direct CO₂ capture to generate syngas. Among the most relevant technological variants are direct air capture (DAC), solid oxide electrolysis and modular microplant design, which optimize energy efficiency and enable industrial scalability in decentralized contexts.

The convergence between high-performance electrolysis, carbon capture and thermal synthesis marks a new frontier in sustainable fuel engineering, consolidating a technology platform adaptable to multiple scales.

Featured projects

• INERATEC: This company has developed modular microplants for the production of e-fuels from captured CO₂ and renewable hydrogen. Its plant in Frankfurt, Germany represents a scalable model for local supply.

• Audi e-diesel: Audi, together with technology partners, has produced e-diesel by combining water, CO₂ and renewable electricity. The process, based on Fischer-Tropsch, generates synthetic diesel with low environmental impact.
• Synhelion (Switzerland/Spain): Using concentrated solar power, this company converts CO₂ and water into syngas, which is then transformed into synthetic gasoline and kerosene, maintaining a focus on supplying aviation with 100 percent solar fuels.
• Norsk e-Fuel (Norway): This initiative develops industrial plants for the production of e-kerosene with hydroelectric power. It is aimed at the aviation sector and is part of the Norwegian goal of carbon-neutral domestic flights by 2030.
• Haru Oni (Porsche-HIF-Siemens Energy): Located in Chilean Patagonia, this pilot plant produces e-fuels through wind-powered electrolysis and direct CO₂ capture. Porsche uses the fuel in racing engines as part of its decarbonization strategy. 

We invite you to watch the following video from Siemens Energy, which reflects the Haru Oni project, located in the Chilean Patagonia, which was the first industrial-scale integrated plant that produces carbon-neutral e-fuels. It uses wind energy to generate green hydrogen through electrolysis, which is then combined with captured CO₂ to synthesize methanol and synthetic gasoline. With an initial capacity of 130,000 liters per year, it is expected to reach 550 million liters by 2027.

Constraints to synfuels implementation

The energy demand and operating costs of synfuels production require intensive electrical inputs, especially in the electrolysis and CO₂ capture stages. This currently raises their price per liter relative to fossil fuels. Currently, the average cost of e-kerosene exceeds USD 2.5/liter versus USD 0.6/liter of fossil kerosene (according to IEA, 2024).

However, the progressive reduction in the price of renewable energy, coupled with process optimization and economies of scale, projects an economic convergence in the next decade. To be truly competitive, it is essential to overcome the challenges of scalability and achieve large-scale production that optimizes costs.

Regarding infrastructure and regulatory framework, although they reuse existing networks, they require investment in scaling and logistics. It is key to establish clear certification regulations, tax incentives and traceability mechanisms to encourage large-scale integration.

Beyond current costs, the massification of synthetic fuel faces the challenge of creating an ecosystem where industrial production capacity and market demand grow synchronously. This requires not only technological investment, but also stable regulatory frameworks that drive adoption and facilitate the development of a robust value chain.

Conclusions

Synthetic fuel is positioned as a technically feasible and essential alternative for sustainable mobility, leveraging existing infrastructure. Produced from renewable hydrogen and captured CO₂, these synfuels reduce dependence on fossils and decarbonize key sectors such as heavy, maritime and air transport, shaping a circular economy. Far from replacing, they complement other technologies such as electromobility and green hydrogen. 

As energy carriers with a low or zero carbon footprint, synthetic fuels make it possible to extend the operating life of thermal engines, contribute to the significant reduction of greenhouse gas (GHG) emissions and facilitate the convergence towards hybrid and sustainable energy systems at a global level. They represent a transitional solution, and consolidate themselves as a strategic link in the reconfiguration of the link between the energy sector and transportation in the context of structural decarbonization.

References

1. Matteo Da Fermo (22, January 2025). Sustainable fuels: what are they and how do they work? https://powy.energy/es/noticias/evolution-news/combustibles-sostenibles/
2. https://www.repsol.com/es/sostenibilidad/ejes-sostenibilidad/medio-ambiente/economia-circular/nuestros-proyectos/combustibles-sinteticos/index.cshtml