Residues from the Oil Pressing Process as a Substrate for the Production of Alternative Biochar Materials

The purpose of this study was to evaluate the feasibility of using residues from cooking oil production to produce alternative biochar fuels along with optimizing the pyrolysis process. The work consisted of carrying out the pyrolysis process at varying temperatures and holding times at the final temperature, and then evaluating the energy potential of the materials studied. Taking into account aspects of environmental emissions, the content of selected oxides in the flue gases generated during the combustion of cakes and the biochar obtained from them was evaluated. Plant biomass derived from a variety of oilseeds, i.e., fennel flower (Nigella sativa L.), rapeseed (Brassica napus L. var. Napus), flax (Linum usitatissimum L.), evening primrose (Oenothera biennis L.), milk thistle (Silybum marianum L. Gaertn.) and hemp (Cannabis sativa L.), was used to produce biochar. The experimental data have shown that the obtained biochar can have a calorific value of nearly 27 MJ kg−1. The use of pyrolysis allowed for a maximum increase in the calorific value of nearly 41% compared to non-thermally processed cakes and a several-fold decrease in carbon monoxide, nitrogen oxides and sulfur dioxide emissions. According to these results, it can be concluded that the pyrolysis process can be an attractive method for using residues from the production of various cooking oils to produce alternative biofuels, developing the potential of the circular economy.