Professor Henrik Leion, based in the Department of Chemistry and Chemical Engineering at Chalmers University of Technology, has spent much of his career exploring how chemistry can contribute to the energy transition. His research ranges from fundamental studies of chemical processes to technologies now used in large-scale energy facilities.
"The work that has had the greatest impact is something I didn't even recognise at the time. The idea was there in our data, but we didn't see where it would lead. Someone else did."
The remark captures something important, not only about Henrik Leion's research, but also about the often unpredictable nature of scientific progress. A finding that initially appeared to be a minor thread in his work was later picked up by colleagues in the division of Energy Technology and developed into a solution that is now used in large-scale energy facilities.
"My motivation as a researcher is to make things better for the world. Climate change is at the heart of that. In recent years, another element has become increasingly important: curiosity. Sometimes you come across something fascinating and simply have to find out how it works."
Leion's research encompasses both technologies that are already making an impact and ideas that remain at an early stage, but which may prove equally important in the future.
Collaboration Across Disciplines
As a child, an academic career was far from an obvious path for Henrik Leion. He grew up on a farm, but following in the family tradition was never really an option.
"One reason was fairly obvious: I'm allergic to pretty much anything with fur, so I realised farming wasn't for me. The other was that I'm dyslexic, and the subjects that came most naturally to me were science and mathematics. Beyond that, it's really a matter of circumstance and chance."
When Leion completed his Master's degree at Chalmers around the turn of the millennium, the dot-com crash had hit and job opportunities were scarce. He applied widely and was offered a doctoral position — a decision that would shape the course of his career.
His research focused on chemical-looping combustion, a technology that uses solid materials to supply oxygen for chemical reactions.
As a PhD student, Leion worked across both the Department of Chemistry and the Division of Energy Technology.
"I was based in Chemistry, but affiliated with Energy Technology, where Professors Tobias Mattisson and Anders Lyngfelt supervised my work. That meant I became very independent early on. When you're given responsibility for organizing and managing things yourself, you learn quickly."
The collaboration between the two disciplines has continued throughout his career.
Tobias Mattisson sees Leion's work as an important bridge between fundamental chemistry and applied energy research.
"To interpret what we observe in large pilot facilities, it is essential to investigate the same processes on a smaller scale, for example through laboratory reactors and chemical analysis. We've learned a great deal from Henrik and his group. It's knowledge we would not have been able to generate ourselves."
"Henrik's contributions have enabled us to connect our applied research much more closely to fundamental chemistry."
For Mattisson, that connection is crucial:
"Many of the technologies we study in Energy Technology, including chemical-looping combustion, are essentially advanced chemical reactors. To understand the reactions and interactions involved, chemistry is absolutely central."
Building an Independent Research Environment
After several years working across both Chemistry and Energy Technology, Leion was given the opportunity to establish his own research direction. He was among the first researchers recruited as part of Chalmers' strategic investment in energy research.
The position allowed him to build a research group of his own and develop the interdisciplinary approach that had shaped his work since his doctoral studies.
Looking back, he believes that already being part of the organisation helped him get started quickly.
"One advantage of internal candidates that people often overlook is that you already understand how the organisation works. That gives you a much shorter start-up period."
For Leion, building a research environment has never been only about research. It has also been about creating opportunities for people.
For many years he has been involved in Jobbsprånget, Sweden's largest internship programme for internationally trained academics. His involvement began after he noticed that highly qualified candidates often struggled to gain a foothold in the Swedish labour market despite strong academic credentials.
Since then, he has hosted numerous interns and encouraged colleagues to do the same. Several have gone on to careers in research and academia. One of the first interns he welcomed, Esraa Darwish, is now a PhD student in the Department of Chemistry and Chemical Engineering.
Combustion Research with a Climate Focus
Much of Henrik Leion's research is driven by the challenge of climate change. His work includes improving energy efficiency, developing more effective fuel production processes and exploring carbon capture technologies linked to combustion.
"I've worked on carbon capture from combustion, but solar and wind have been more successful. Not every technology wins the race, but that doesn't mean the problem has gone away."
A central focus of his research is the development of so-called oxygen carriers — materials that transport oxygen in solid form, making it possible to control combustion processes in new ways.
"My research is about supplying only the oxygen, and not everything else. That means you avoid having to separate large volumes of gases afterwards."
By controlling how and when oxygen is supplied, combustion processes can be made more efficient while also creating better conditions for reducing emissions.
Much of this work remains at the research stage. Alongside technologies that have already found industrial applications, Leion has contributed to several important scientific advances in understanding how oxygen carriers behave.
His work includes developing some of the first materials for CLOU (Chemical Looping with Oxygen Uncoupling), a process in which oxygen can be released directly from the material itself. He has also helped explain how substances such as nitrogen and sulphur affect these materials, and how solid fuels and ash interact with them during combustion.
This type of work is often referred to as proof-of-concept research: demonstrating that something can work in principle. It may never become a commercial technology itself, but it provides the knowledge needed for future innovations.
"There is always a chain behind everything. When you teach the First World War, you don't start with the ancient Greeks, but they're still there in the background."
Chemical-looping combustion research at Chalmers is itself the result of decades of scientific development, with researchers such as Anders Lyngfelt helping to lay the foundations.
From Unexpected Finding to Industrial Application
This was the work Leion was referring to at the beginning of the interview when he described it as the most impactful outcome of his research.
What has now become a practical technology was never intended to be the main focus of the project.
Instead, a line of inquiry that emerged from Leion's research was taken forward by colleagues in Energy Technology and eventually developed into the company Improbed AB. The concept replaces sand in a fluidised bed with engineered materials that actively influence the combustion process.
What followed was a journey from laboratory experiments to full-scale trials in combined heat and power plants. By replacing conventional sand with an oxygen-carrying bed material, researchers demonstrated higher efficiency, more stable combustion and lower emissions — results that now underpin commercial applications.
"At a technical university, it is important to be able to connect research to concepts and technologies that can benefit society. The way we have worked together has allowed us both to deepen our understanding and to scale up the technology," says Tobias Mattisson.
Leion emphasises that the development was gradual and depended on the contributions of many researchers.
"I don't want to take credit for it," he says.
Today, the technology is used in large-scale industrial facilities.
"A typical boiler can improve its efficiency by somewhere between five and twenty per cent. Even a five per cent increase is significant when you're dealing with systems of that scale."
A Research Environment Built for the Unexpected
When establishing his research environment, Leion made a conscious decision not to optimise it for a single process or technology.
"It turned out well because I always thought I'd end up doing something else."
Instead, the laboratory was designed to accommodate a wide range of experiments and research questions. The result was an unusually flexible environment where new ideas and unexpected research directions could be explored as they emerged.
But the story does not end there.
Leion sees the next step in continuing to build on the same principle that underpins Improbed: using materials that actively influence combustion processes. By exploring alternatives to the materials used today, researchers may be able to further improve both efficiency and operational stability.
"The first material we happened to test was the one that was taken forward. There is still a great deal out there that has never been tested."
RELATED CONTENT:
New type of sand boosts waste-to-energy plant performance
Researchers at Chalmers have discovered that a specific type of bed material can significantly increase efficiency while reducing operating and maintenance costs in the combustion of waste and biomass. In collaboration with E.ON, they have demonstrated that the concept works in today’s commercial boilers.
The findings make modern combined heat and power (CHP) plants highly attractive from both an economic and climate perspective, while also opening up opportunities for smarter designs in the next generation of energy facilities.
Existing biomass boilers could support Sweden’s entire transition to renewable fuels
A transition to renewable production of heat, electricity and fuels could also create new opportunities for a wide range of industries to manufacture renewable products. As Chalmers researchers now summarize ten years of energy research, they highlight major technological advances across the field.
“The potential is enormous. Existing energy facilities in Sweden alone could produce renewable fuels equivalent to 10 per cent of global aviation fuel demand if such a transition were fully implemented,” says Henrik Thunman, Professor of Energy Technology at Chalmers.
How to move from fossil dependence to renewable alternatives remains a key challenge for many industries. For heavy industries such as oil refineries and the pulp and paper sector, the transition is particularly urgent because investment cycles are long. At the same time, investments must be carefully planned to avoid premature replacement of boilers or other facilities, which would entail substantial costs. Thanks to a long-term strategic research effort, Chalmers researchers have now paved the way for a radical transition that would also enable more than one hundred existing facilities in Sweden to remain in operation.
▶ Read more in the press release (in Swedish, May 21, 2018)
▶ Chalmers Power Central
- Director of Master's Programme, Undergraduate Education (GRU)
- Full Professor, Energy Technology, Environmental and Energy Sciences
- Projectleader Research, Energy Technology, Environmental and Energy Sciences
