A critical review on second- and third-generation bioethanol production using microwaved-assisted heating (MAH) pretreatment

Jherwin B. Ocreto, Wei Hsin Chen, Aristotle T. Ubando, Young Kwon Park, Amit Kumar Sharma, Veeramuthu Ashokkumar, Yong Sik Ok, Eilhann E. Kwon, Analiza P. Rollon, Mark Daniel G. De Luna

Research output: Contribution to journalArticlepeer-review

35 Citations (Scopus)


In the pursuit of the 7th Sustainable Development Goal (SDG) of the United Nations, it is driven to develop affordable, sustainable, and clean energy. Second (lignocellulosic) and third (microalgae and macroalgae) generation bioethanol appear to be the most favorable renewable feedstocks to meet SDG 7 pursuance. However, several feedstock pretreatments have shown process challenges in terms of yield and product inhibitors. Microwave-assisted heating (MAH) has gained positive attention as a novel alternative method for pretreatment heating in the global community due to its numerous advantages over conventional heating. Therefore, current studies and progress in MAH pretreatment for bioethanol production are critically reviewed. The effects of different parameters on MAH pretreatment are also examined. The application of MAH pretreatment demonstrates rapid reaction exhibiting remarkable improvement in sugar recovery and fewer inhibitors over conventional heating. Despite these advanced results, certain obstacles remain to be addressed and improved until it is ready for industrial scalability. It includes understanding the interaction and relationship between the different parameters like biomass loading, catalysts, temperature, power intensity, contact time, and pressure for reactor design. Moreover, factors such as the non-thermal effect, dielectric properties of different biomass materials, and controlled temperature need to be further explored and evaluated. Thus, continuous research and development efforts on MAH pretreatment are encouraged to become commercially feasible for the applications of bioethanol production.

Original languageEnglish
Article number111679
JournalRenewable and Sustainable Energy Reviews
Publication statusPublished - 2021 Dec

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Ltd


  • Algae
  • Bioethanol
  • Lignocelluloses
  • Microwave-assisted heating
  • Sustainable development goal
  • Torrefaction

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment


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