Microwave processing of oil palm wastes for bioenergy production and circular economy: Recent advancements, challenges, and future prospects

• Main Authors: Foong, S.Y., Chan, Y.H., Lock, S.S.M., Chin, B.L.F., Yiin, C.L., Cheah, K.W., Loy, A.C.M., Yek, P.N.Y., Chong, W.W.F., Lam, S.S.
• Format: Article
• Published: 2023
• Online Access: http://scholars.utp.edu.my/id/eprint/34126/; https://www.scopus.com/inward/record.uri?eid=2-s2.0-85144082890&doi=10.1016%2fj.biortech.2022.128478&partnerID=40&md5=500f47b5ad44b261f0921d384e75f46d

The valorization and conversion of biomass into various value-added products and bioenergy play an important role in the realization of sustainable circular bioeconomy and net zero carbon emission goals. To that end, microwave technology has been perceived as a promising solution to process and manage oil palm waste due to its unique and efficient heating mechanism. This review presents an in-depth analysis focusing on microwave-assisted torrefaction, gasification, pyrolysis and advanced pyrolysis of various oil palm wastes. In particular, the products from these thermochemical conversion processes are energy-dense biochar (that could be used as solid fuel, adsorbents for contaminants removal and bio-fertilizer), phenolic-rich bio-oil, and H2-rich syngas. However, several challenges, including (1) the lack of detailed study on life cycle assessment and techno-economic analysis, (2) limited insights on the specific foreknowledge of microwave interaction with the oil palm wastes for continuous operation, and (3) effects of tunable parameters and catalyst's behavior/influence on the products� selectivity and overall process's efficiency, remain to be addressed in the context of large-scale biomass valorization via microwave technology. © 2022 Elsevier Ltd