The 2023 Vattenfall Prize for best thesis

Petter Paulsen Thoresen, visiting researcher in chemical engineering at Luleå University of Technology, is awarded the 2025 Vattenfall Prize for the best doctoral thesis.

“When my thesis was submitted as a nomination for the award, I didn’t have high expectations, as there is so much excellent research being conducted at Luleå University of Technology. That’s why I was genuinely surprised and delighted when Vattenfall called me last autumn to announce that I had actually won! It was especially meaningful that Lovisa Fricot Norén, CEO of Vattenfall Vattenkraft AB, had prior knowledge of the research field, its complexity and challenges. Genuine recognition of the difficulties we face daily in research makes the award all the more rewarding,” says Petter Paulsen Thoresen.

Thoresen’s research focuses on improving the utilisation of lignocellulose – forest-based biomass – with a particular emphasis on lignin, one of the main components of wood. He has extracted lignin from trees such as spruce, birch and beech using water and organic solvents, resulting in a brown powder. To create value, it is essential to understand how this lignin can be used. Since lignin is chemically diverse and changes during extraction, detailed chemical characterisation is required. Furthermore, lignin forms tiny, invisible aggregates that affect its properties, such as its antioxidant capacity. Thoresen has investigated how these aggregates can be reversed, which alters the lignin’s functionality. This aspect of lignin behaviour remains largely unexplored and may represent the next important step in lignin research – enabling the development of new sustainable products from forest resources.

“We are very proud that Vattenfall’s award of SEK 75,000 for best doctoral thesis 2025 goes to Petter Paulsen Thoresen. His research in biochemical process engineering is highly relevant to the development of the bio-based economy. Petter’s thesis is a significant contribution to the advancement of the circular economy and the pursuit of the global sustainability goals – a mission of great importance for a fossil-free future,” says Lovisa Fricot Norén, CEO of Vattenfall Vattenkraft AB.

The award statement of the jury:

“Vattenfall’s prize for best doctoral thesis 2025 is awarded to Petter Paulsen Thoresen for his dissertation in biochemical process engineering: Structure and Property Oriented Organosolv Lignin Extraction. The thesis explores parameters for tailored lignin extraction using organosolv processes, aiming to control and optimise structure–property relationships. It comprises six scientific publications of high international standard. Thoresen has also presented his findings at seven international research conferences and co-authored four additional publications, demonstrating both breadth and impact in his research – with particular relevance to the bio-based economy. His thesis transcends disciplinary boundaries by applying design principles to address the complex and challenging properties of technical lignin and other biopolymers. By linking material properties to process design, new knowledge is generated that deepens scientific understanding and promotes industrial innovation in sustainable materials. The research enables high-value applications of lignin and contributes to the transition towards a more bio-based industrial system. The thesis is therefore a vital contribution to the development of the circular economy and the work to achieve the global sustainability goals – a mission that is both timely and strategically crucial for a fossil-free future.”