Fuel development as a systems discipline – interview with A. Ferrari

What makes a good fuel? According to Alessandro Ferrari, the answer lies not in individual properties, but in the interaction between fuel, engine and application. In this interview, the Head of Development Performance Fuels at Haltermann Carless discusses modern fuel development, testing expertise and the future of sustainable mobility. 

Alessandro Ferrari, where does "fuel formulation" end and where does true "systems development" (fuel, engine and application) begin? 

Fuel formulation initially involves selecting and combining components and additives to achieve specific chemical and physical properties. For me, true development only begins when we also consider the engine and the intended application.

A fuel never delivers its performance in isolation. It influences combustion, efficiency, emissions, component protection and driveability, while engine architecture, calibration and operating conditions also influence the fuel. That is why we now view fuel, engine and application as a single integrated system.

The key question is no longer, "Is this a good fuel?" but rather, "Does this fuel deliver the desired outcome within a specific system?"

This systems perspective is also reflected in our team. At Haltermann Carless, fuel development is driven by close collaboration between chemists, engine specialists and advanced analytical experts.

As a result, we develop solutions whose full potential is only realised when fuel, engine and application work together.  

Haltermann Carless is a leader in the development of test and reference fuels. What role does this expertise play in your day-to-day development work? 

For us, test and reference fuels are far more than testing media. They follow highly precise specifications and provide the foundation for reproducible and reliable development results.

We also develop specialised test fuels designed to replicate specific engine effects, such as injector deposit formation or other critical operating phenomena.

OEMs use these fuels to develop and homologate new engine and vehicle concepts, while additive manufacturers use them to develop and qualify their products. As a result, test fuels have become a vital part of the entire testing ecosystem.

The interaction between fuel and engine is always critical. Only when we understand which fuel properties cause which effects in an engine can we develop and optimise solutions in a targeted way.

New propulsion concepts, changing regulatory requirements and new feedstock sources continuously create new challenges. That is why we regularly evaluate new approaches and technologies, enabling us to identify opportunities early and translate them into practical solutions together with our customers. 

When does a good fuel become a truly reliable development result? 

Only when results are reproducible. That is precisely why test and reference fuels play such an important role. They create defined and stable conditions that allow differences in engines, hardware or additive technologies to be assessed reliably.

Only then can results be compared, developments validated and new solutions refined effectively. 

What does a fuel development expert really need to understand about engines beyond the basics? 

A fuel developer first needs to understand that there is no such thing as a single, universal engine. Even within the automotive sector, there is a wide range of concepts, from petrol and diesel engines to two-stroke and four-stroke designs, port and direct injection systems, turbocharged and naturally aspirated engines. Differences in combustion chamber design, engine speed range and operating strategy add further complexity. Vehicle engines are only part of the picture; turbines and aircraft engines, for example, place very different demands on fuel.

Two phases are particularly important because this is where fuel has the greatest influence: injection or evaporation, followed by combustion. Mixture formation determines how effectively fuel and air combine.

It is equally important to understand what an engine was designed to achieve. A production engine must operate reliably for many years and perform with a broad range of specification-compliant fuels. A racing engine has a very different objective: maximum efficiency and performance under tightly controlled conditions.

That is why fuel development goes far beyond chemistry. It requires an understanding of how engine, application and fuel interact as a complete system.

How do you translate specific engine requirements, such as knock tendency, injection strategy or deposits, into chemical and physical targets during fuel development? 

In practice, we rarely start with a blank sheet of paper. Most fuels must comply with predefined specifications, such as fuel standards for production vehicles or FIA regulations in motorsport. Within these boundaries, however, there is often considerable flexibility in selecting and combining suitable components.

We are almost always looking for the best compromise. Optimising a single property in isolation rarely delivers the right outcome. For example, high chemical reactivity may improve combustion efficiency, while under certain conditions it can also increase the tendency for engine knock. 

How are stricter emissions and particulate requirements changing the way fuels are developed, tested and validated today? 

Stricter emissions and particulate regulations have significantly shaped both engine and fuel development in recent years. The objective is straightforward: to convert as much of the energy contained in the fuel as possible into useful work. Greater efficiency means lower fuel consumption for the same performance and therefore lower CO₂ emissions.

The direction of travel is increasingly defined by regulation. Emissions standards such as Euro IV, Euro V, Euro VI and the upcoming Euro VII require manufacturers to continuously reduce both fuel consumption and emissions. As a result, engines are being designed to utilise fuel more efficiently than ever before.

At the same time, fuels themselves are evolving. Today's standard fuels increasingly contain sustainable components such as ethanol, biodiesel and HVO, while still needing to meet the requirements of modern engines.

These changes are also reflected in the demands placed on test and reference fuels. They must accurately and reproducibly represent the properties of current and future market fuels to support the development, testing and homologation of new engine technologies. 

Beyond the product itself, what makes Haltermann Carless a true development partner for OEMs and industry?

What sets Haltermann Carless apart, in my view, is the combination of fuel expertise and application knowledge. We understand the chemistry and physics of fuels while also recognising the requirements of the applications in which they are used.

This enables us to develop solutions tailored to specific use cases. Our customers benefit from a combination of fuel expertise, systems understanding and many years of development experience.

Where do you see the biggest misconceptions about modern fuel development?

Too often, discussions imply that there is a single solution for the future of mobility. In reality, particularly when it comes to sustainable fuels, the picture is far more diverse.

We are not talking about one technology but a broad spectrum, ranging from biofuels from different feedstocks to HVO, bioethanol and e-fuels. Each option has its own strengths and areas of application.

The debate is also frequently framed as "electrification versus sustainable fuels". I believe this is an oversimplification. The challenge is so significant that we should make use of every viable technology wherever it can make the greatest contribution.

What role will sustainable fuels play in the future mobility technology mix?

The engine and mobility expert Kelly Senecal summarises this idea in a well-known phrase: 

"The future of mobility is not electric, it is eclectic." 

To me, this means that the future of mobility will not be shaped by a single solution, but by an intelligent combination of technologies, energy carriers and applications. That is why it is essential to evaluate every option based on facts, application requirements and real-world benefits rather than simplified either-or debates.

Thanks for the interview.       

Do you have any questions? We look forward to hearing from you.