Biorefining of ethanol and methane from NaOH pretreated poplar residues: Mass balance and energy flow analyses

• Published in: Fuel (Guildford) 2023-02, Vol.333, p.126293, Article 126293
• Main Authors: Wu, Peiwen, Li, Lianhua, Zhou, Yangyan, Wang, Wen, Sun, Yongming, Guo, Yufang, Kang, Xihui
• Format: Article
• Language: English
• Subjects: Advanced biofuels; Anaerobic digestion; Mass balance; Poplar; Waste valorization
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2022.126293

This illustrates that the gross energy output from the co-production (ethanol and methane) process of NaOH-treated Poplar outperformed the stand-alone production process (ethanol or methane). [Display omitted] •Conversion efficiency of poplar residues to ethanol or/and biogas was evaluated.•Energy conversion efficiency of co-production was 1.2 times of ethanol production.•1 kg NaOH pretreated poplar residues yielded 158.2 g ethanol and 103.3 g methane.•1 kg pretreated poplar yielded 9.5 MJ of gross energy via the coproduction process. Poplar, a crucial player in lignocellulosic biofuel production worldwide, can be divided into five types. The feedstock variability would significantly impact the scale-up and commercialization of biofuel technologies from poplar. To date, few studies were found comparing ethanol and biogas production from different types of poplar. This study compared the conversion efficiency of NaOH pretreated five types of poplar residues to ethanol and biogas under three biological conversion processes (namely ethanol fermentation process, anaerobic digestion (AD) process, and cascading ethanol fermentation and AD process); the flow of mass, carbon, nitrogen and energy were also analyzed by material flow analysis. 48.4–60.1 % of theoretical ethanol yield, and the specific methane yield of 201 ± 11.0–270 ± 3.40 mL/g volatile solids were obtained under the co-production process, with the highest yield from Populus trichocarpa (N2). These results showed that the co-production process (cascading ethanol fermentation and AD process) of poplar N2 outperformed ethanol fermentation and AD in terms of energy conversion efficiency, which was 121 % and 42.9 % higher than the ethanol fermentation process and AD process, respectively. Mass and energy balance analysis showed that under the co-production process, 158 g ethanol and 103 g methane could be obtained from 1 kg pretreated poplar N2, corresponding to a total energy output of 9.5 MJ, with an energy conversion efficiency of 54.3 %. This study may provide new insights into the breeding of new poplar species for the current biorefinery process.