Our research

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Research on impurities in charcoal-based grilling fuels were started in 2016 by dr. Zbigniew Jelonek from the University of Silesia in Poland. Eventually the research was extended to wood pellets and other types of biomass fuels like grass or sunflower husk pellets.

Concerns about climate change, energy security, and the diversification of energy supplies make biomass an increasingly more attractive and essential energy source. Biomass fuels have experienced rapid growth, especially in the European Union, the USA, and China. This expansion should continue globally for the foreseeable future. A better understanding of biomass fuels quality and the human health and environmental implications arising from their combustion is therefore an urgent and very timely research direction. 

In the last few years we have analyzed over 200 charcoal-based and more than 700 wood pellet fuel samples from 9 different countries. Some of these fuels contained variety of contaminants, exhibiting in some extreme cases as much 26 vol. % of impurities. Our team defined, described and documented these impurities and created classifications allowing for easier and more precise contaminant identification.

Although most impurities are recognizable only under a microscope, some of these fuels contained contaminants visible even with a naked eye. Some impurities come are from the wood structure, harvesting method, and transportation. Others, like metal, rust, oil, and grease, can be introduced during manufacture. Such impurities are acceptable at low levels.

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However, additional contaminants can result from machinery malfunctions or inadequate source material (e.g., old furniture or construction materials that contain glues, resins, or paint). In some instances, their presence results from a lack of attention (e.g., plastic bags), or they may be intentionally added (e.g., plastic and tire rubber) to facilitate the ignition and increase heat output. Therefore, testing of solid biomass fuels is of critical importance because these contaminants can lead to emissions of carcinogenic compounds and harmful particulate matter.

Wide range of documented by us impurities clearly demonstrate that currently used physical and chemical analyses are not sufficient to guarantee high quality of fuel.

A quick and reliable solution for identifying and quantifying impurities is through reflected light microscopy. Although this method is a well-known and widely used analytical technique for coal, source rocks, metals, ceramics, and polymers, it is a novel application for solid biomass fuels.


This methodology, developed by our research team, is an excellent tool for solid biomass quality testing; it can help to assure the production of superior quality fuels.

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photo by Henry Philips

Our research focuses also on assessing the quality of the released flue gas and the quantity of emitted particulate matter during biomass combustion and gasification. 

Because the properties of raw fuels affect the characteristics of emissions, the assessment of the solid biomass fuels should be of critical importance. It is especially essential in case of grilling fuels as smoke from their combustion has direct contact with food, impacts human safety, and pollutes the atmosphere.

In some instances, petrographic results can be correlated with emissions, which means that there is a possibility of predicting harmful air pollutants from the biomass fuel composition.