Co-pyrolysis of waste wind turbine blades and biomass using fixed-bed pyrolysis plant

This work aims to study the co-pyrolysis of waste wind turbine blades (WTB) and wheat straw (WS) biomass using a bench fixed-bed pyrolysis plant, allowing for the quantification of representative products. The co-thermal process was carried out on WTB consisting of glass fiber-reinforced unsaturated polyester resin and blended equally with WS. To obtain the highest yield of the high-value oil pyrolysis product, the conversion process was carried out at different temperatures of 450, 500 and 550 °C. The co-pyrolysis gaseous and liquid products were characterized using GC-TCD and GC-MS, respectively, while the composition and morphology of its solid residues were examined using SEM-EDX. The results showed that oil production increased significantly to 33.9 wt% at 450 °C and then decreased markedly to 22.9 wt% at 550 °C. In contrast, the highest gaseous yield (32.7 wt%) was obtained at 550 °C, compared to 26.9 wt% at 450 °C due to oil oxidation. A significant reduction in solid residue (39 wt%) was also observed compared to that obtained from typical WTB pyrolysis (55 wt%). 1,2-Benzenedicarboxylic acid (27.12%), acetic acid (23.88%), terephthalic acid, di(2ethylhexyl) ester (57.54%), and benzene, 1,1'-(1-butene1,4-diyl) bis-, (Z)- (23.79%) were the predominant compounds that are commonly used in resin production as plasticizers, coatings, and adhesives. A small amount of styrene (≤15.94%) was also observed in the condensate component along with other compounds such as benzene, 1,1'-(1,3 propanediyl) bis- (up to 32.01%) and terephthalic acid, di(2ethylhexyl) ester (up to 32.57%). While the gaseous product was loaded with CH₄ and H₂ gases, especially at high temperatures. Recycled fibres at 500 °C showed better morphology, cleaner surface, and sharper edges compared to other conditions. While the char product was rich in carbon and loaded with calcium, magnesium, potassium and sodium. Accordingly, it can be asserted that co-pyrolysis is a promising solution for processing WTB and WS together and converting them into high-energy-added products and short fibres with low styrene content.