The doctoral dissertation in the field of Forestry will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus and online.
What is the topic of your doctoral research? Why is it important to study the topic?
Aiming for fossil-free energy and materials, versatile approaches can broaden the resource portfolio. Bioenergy and biorefineries are closely linked to low-cost and domestic availability of feedstocks, improving competitiveness against fossil-based products and services. In this context, new biomass resources should be investigated, including dedicated energy crops that do not threaten food production, food residues and byproducts with no current particular use, and native tree species with little knowledge about them that could be integrated into forest management practices within a bioeconomy framework.
Biomass solid fuels must meet certain certification thresholds. Thus, our results, tied to combustion properties, both physical and chemical, are in line with the recommended market certification schemes. This, in turn, shows the potential of the studied materials for commercialization applications.
What are the key findings or observations of your doctoral research?
The energy crops from the first study could serve as a starting point for crop-based pellet production under Nordic climatic conditions, as no previous studies have examined these species under the same conditions. Hydrothermal processing elevated the released energy of coffee silverskin and spent coffee grounds, and the hydrochar contained a substantial number of chemical compounds suitable for valorization in biorefineries. The thermal processing of the coffee residues has been a high-interest topic over the past few years. Similarly, all native tree species exhibited good properties for combustion, with a select few combining high heating values with minimal ash yield. So far, very little has been known about the specific properties of the referred species.
However, a few results – such as pellet mechanical durability, as well as the ash and chemical content of the hydrothermal coffee-derived by-products and residues – indicate the need for future studies. Although all native tree species yielded favorable combustion properties, these findings should be integrated with their geographical distribution and dendrometric characteristics. A comprehensive analysis that encompasses multiple parameters can foster sustainability and minimize environmental disturbance.
How can the results of your doctoral research be utilised in practice?
My work incorporates three types of lignocellulosic biomass for bioenergy and biorefinery applications. Despite the disparities that arise in biomass use for bioenergy, as they are not homogeneous, there are utilization routes through the choice of the best-suited approaches. As I previously mentioned, a key success factor is availability at the domestic level. This is in correlation with parameters such as species origin, land availability, biodiversity, transportation feasibility, and mill network, setting up the basis for robust bioeconomy systems. This could be rather important for rural areas, as an additional source of revenue for local communities. For instance, the native tree species originate from a low-income region, and some of these species are a common resource for firewood. This paves the way for sustainable forest management of species adapted to geographical and ecological conditions, a wood-based bioeconomy, and subsequently, new bioenergy products and services.
What are the key research methods and materials used in your doctoral research?
Apart from describing the energy content of the samples, we pay attention to describing the physical and chemical characteristics. The bulk density and the mechanical durability of pellets are associated with the handling and transportation of pellets. The chemical content not only affects the combustion process, for instance, with ash formation, but could also pose subsequent impacts. More specifically, high Cl and S contents could corrode the boiler in the long term. Other parameters described are soil profiles for the first and third studies, yield productivity of the energy crops, and Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analyses for the coffee materials. It is important to mention that the delivered raw materials needed pre-treatments, being subjected to separation of the wood from the bark and size reduction for both crops and wood.
Is there something else about your doctoral dissertation you would like to share in the press release?
All my research studies relied on extensive laboratory work for many hours. On the other hand, it gave me the chance to gain a deeper understanding of the biomass processing mechanisms. I also had a lot of support from my office and laboratory mates, who encouraged me no matter the drawbacks that sometimes occurred during the laboratory tasks.
The doctoral dissertation of Nikolaos Papamatthaiakis, MSc (Agr & For), entitled Valorization of non-traditional lignocellulosic feedstocks for bioenergy and biorefinery applications will be examined at the Faculty of Science, Forestry and Technology, Joensuu campus. The opponent will be Associate Professor Sara Gonzalez Garcia, University of Santiago de Compostela, Spain, and the custos will be Professor Blas Mola-Yudego, University of Eastern Finland. Language of the public defence is English.
For further information, please contact:
Nikolaos Papamatthaiakis, [email protected]
