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Researcher Yuri Kroyan isn’t working on easy questions. He’s trying to figure out how alternatives to fossil fuels could better power planes, trains, automobiles and ships. It’s a hugely complex question: one that’s not just about how much fuel cars consume but also about local climates, social factors, economic trends, and infrastructure like roads and refueling stations.

In his work at the energy company Neste, Kroyan, who graduated from Aalto University in late 2022 with a doctorate in energy technology, looks for answers with the help of statistical modelling. As Kroyan’s mathematical models churn out projections of how to best replace carbon-based fuels with renewables, decision-makers from the European Commission to energy industry C-suites pay attention.

But it wasn’t always like that. When Kroyan was supposed to start work at Aalto on a doctoral research project called ADVANCEfuel, he had no idea where to begin. 

‘We needed to model the impact of advanced fuel properties on end-use performance, meaning fuel consumption, emissions and stuff like that. But how do you do that so that the model is flexible enough to describe both a single vehicle and an entire country?’

It’s best to pause here and explain that the ‘advanced’ refers to biofuels made from non-food biomass such as agricultural waste. Biofuels can be blended with or used to replace liquid fossil fuels, which reduces emissions.

There was almost no data available, but after countless hours the team figured it out. ‘We started looking at the performance of alternative fuels relative to fossil fuels that were taken from the same source. We knew that their properties, like density, octane and cetane numbers, vapor pressure and distillation points, compared to their fossil counterparts. We saw how these properties shifted with changes in fuel consumption.’

That relative analysis cracked it. Kroyan built models that could use existing data points to describe fuel consumption in light-duty gasoline vehicles and aircraft, while his colleague Michał Wojcieszyk built the models for diesel vehicles. After verifying the results and writing a stack of papers, the next step was obvious.  

‘We created a tool for the European Commission and European industries to support their regulatory and decision-making processes.’

That’s the gist of statistical modeling: creating reliable predictions from limited data. 

‘In general, modelling is about finding the continuity of what you observe. You see certain phenomena, perhaps you have a few points of data. Then you want to understand what is between those points and what lies beyond them. That’s where statistical modelling comes in.’

Statistical modelling is a powerful tool for emerging technologies and vast, complex issues, like decarbonising transportation. In the best case, the results steer both public policy and private enterprise. For Kroyan, statistical modeling is a way to affect real change in the world and put his varied background to work.

Working against the clock

At Neste, Kroyan builds statistical models that tell the company’s decision-makers how to move away from fossil fuels in an impactful way that also makes sense from an investment standpoint. The race is on for the energy sector as Kroyan says the world, the economy, and everything else are on a timer.

‘We take fossil fuels for granted because we have plenty now. But one day they will run out. Power-to-X technologies like hydrogen and carbon capture are expensive and are still in the early stages, but they will scale well enough to transform the sector in the coming decades.’

According to Kroyan, alternatives like longer hydrocarbon chain fuels, such as renewable diesel or sustainable aviation fuels, could be used in existing infrastructure (as so-called ‘drop-in fuels’) bringing faster and more cost-effective reductions in the carbon footprints for those sectors.

Kroyan points out the challenge is also deeply layered and loops in on itself.

‘For example, electric vehicles are treated as zero-emission vehicles. But there are emissions related to the manufacturing of batteries and the mining and processing of minerals. And then there is the question of what source the electricity comes from.’

Kroyan says addressing climate change by decarbonising global transportation on air, land, and sea has to be comprehensive. ‘All potential technologies should be on the table, from electrification and biofuels to hydrogen and more, to achieve genuine transformation and a reduction in greenhouse gas emissions. They should go hand-in-hand, because the magnitude of the decarbonisation challenge is so big we cannot afford to pick and choose. Unexpected discoveries can lead to surprising scalability, so it’s crucial not to pick favourites early on.’

Some might be daunted by the sheer scale of the problem, but Kroyan relishes working on it because, simply put, ‘renewable fuels can be better than fossil fuels.’ We just need to find the best technologies and make the right policy decisions to realise their utmost potential. That might take some statistical modelling.

Yuri Kroyan

• Graduated in 2014 with a bachelor’s degree in Advanced Materials and Nanotechnology from Jagellonian University in Krakow, Poland.
• Studied in the Joint Nordic degree programme, graduated in 2018 with a double-degree Master’s in Innovative Sustainable Energy Engineering.
• Doctoral researcher in Professor Emeritus Martti Larmi’s Thermodynamics and Combustion Technology research group. Completed a doctorate in Energy Technology at the School of Engineering in 2022.
• School of Engineering’s publication of the year for the paper “Modeling the effects of fuel properties on end-use performance in light-duty road transport and aviation” (2022).
• Associate at Neste since 2022 with a focus on gasoline, aviation, and powertrains. Won Neste CEO's Innovation Award 2022.

This article has been published in the Aalto University Magazine issue 37, February 2026.