Can Synthetic Fuels Save the Combustion Engine?

Introduction

The internal combustion engine (ICE) has been the backbone of global transportation for over a century. However, with increasing pressure to reduce carbon emissions and combat climate change, the future of gasoline and diesel engines appears uncertain. Electric vehicles (EVs) are rapidly gaining market share, and many governments are imposing bans on the sale of new fossil-fuel-powered cars within the next few decades.

Amid this transition, synthetic fuels—also known as e-fuels—have emerged as a potential lifeline for combustion engines. These fuels, produced using renewable energy and carbon capture, promise near-carbon-neutral operation while preserving the familiar mechanics of traditional engines. But can they truly save the combustion engine from obsolescence, or are they merely a temporary solution in an electrified future?

What Are Synthetic Fuels?

Synthetic fuels are artificially created hydrocarbons designed to mimic conventional gasoline, diesel, or jet fuel. Unlike fossil fuels, which are extracted from the ground, e-fuels are manufactured through chemical processes that combine hydrogen (produced via electrolysis using renewable electricity) with carbon dioxide (captured from the atmosphere or industrial sources). The result is a liquid fuel that can be used in existing engines with little to no modification.

There are several types of synthetic fuels:

1. E-gasoline & E-diesel – Nearly identical to their fossil counterparts, these can be used in standard ICE vehicles.
2. E-methanol & E-ethanol – Alcohol-based fuels that can be blended with gasoline or used in flex-fuel engines.
3. E-kerosene – A sustainable alternative for aviation, where electrification remains challenging.

The Environmental Promise of E-Fuels

The primary advantage of synthetic fuels is their potential for carbon neutrality. Since the CO₂ released during combustion is theoretically offset by the CO₂ captured during production, e-fuels could drastically reduce the net emissions of ICE vehicles. Additionally, they can be produced using renewable energy, further minimizing their environmental impact.

Another benefit is compatibility. Unlike hydrogen fuel cells or battery-electric systems, synthetic fuels require no major infrastructure overhaul. Existing gas stations, pipelines, and engines can remain in use, easing the transition away from fossil fuels without requiring consumers to abandon their current vehicles.

Challenges and Limitations

Despite their promise, synthetic fuels face significant hurdles:

1. Energy Inefficiency

Producing e-fuels is energy-intensive. Electrolysis, carbon capture, and fuel synthesis require vast amounts of electricity. According to some estimates, an EV powered by renewable energy is three to five times more energy-efficient than an ICE vehicle running on e-fuels. Given the global push for energy conservation, this inefficiency could limit their widespread adoption.

2. High Production Costs

Currently, synthetic fuels are far more expensive than conventional gasoline or diesel. Scaling up production to meet global demand would require massive investments in renewable energy infrastructure and carbon capture technology. Without substantial subsidies or carbon taxes, e-fuels may struggle to compete economically with both fossil fuels and electric alternatives.

3. Limited Availability

While some companies, such as Porsche and Siemens Energy, are investing in e-fuel production, the industry is still in its infancy. Most synthetic fuel projects are small-scale, and widespread commercial availability remains years—if not decades—away.

4. Competition from Electrification

Battery technology is advancing rapidly, with EVs becoming more affordable and capable. Governments worldwide are incentivizing electric mobility through tax breaks, charging infrastructure investments, and outright bans on ICE vehicles. In this context, synthetic fuels may struggle to gain traction outside niche applications like aviation, shipping, and classic car preservation.

Potential Applications: Where E-Fuels Could Thrive

While synthetic fuels may not replace gasoline and diesel entirely, they could play a crucial role in specific sectors:

1. Aviation and Shipping

Battery-electric solutions are impractical for long-haul flights and cargo ships due to energy density limitations. E-kerosene and e-methanol could provide a viable decarbonization pathway for these industries.

2. Motorsports and High-Performance Vehicles

Formula 1 and other racing series are exploring carbon-neutral synthetic fuels to maintain the excitement of combustion engines while meeting sustainability goals. High-end automakers like Porsche are also investing in e-fuels to keep their legacy sports cars on the road.

3. Classic and Vintage Cars

For enthusiasts who cherish historic vehicles, e-fuels offer a way to preserve these machines without contributing to climate change.

Conclusion: A Niche Solution or a True Savior?

Synthetic fuels present an intriguing possibility—a way to reconcile the environmental imperative of decarbonization with the cultural and mechanical legacy of the combustion engine. However, their high costs, energy inefficiency, and the rapid rise of electrification suggest that they are unlikely to fully replace fossil fuels in mainstream transportation.

Instead, e-fuels may serve as a complementary solution, bridging the gap in sectors where electrification is not yet feasible. For the combustion engine to survive in the long term, synthetic fuels must overcome significant economic and logistical barriers. Otherwise, they may remain a fascinating but ultimately limited footnote in the broader transition to sustainable mobility.

The question remains: Can synthetic fuels save the combustion engine? Perhaps not entirely—but they might just buy it some extra time.