Current status of biogas upgrading for direct biomethane use: A review

Muhammad Usman Khan, Jonathan Tian En Lee, Muhammad Aamir Bashir, Pavani Dulanja Dissanayake, Yong Sik Ok, Yen Wah Tong, Mohammad Ali Shariati, Sarah Wu, Birgitte Kiaer Ahring

Research output: Contribution to journalReview articlepeer-review

146 Citations (Scopus)


Anaerobic digestion produces biogas, a mixture of CH4 and CO2, where CH4 is a low cost, environmentally friendly, and renewable energy source. The application of biogas production is increasing rapidly as a means of reducing the pollution impact of organic biomasses. However, biogas contains unwanted elements such as hydrogen sulfide, carbon monoxide, siloxanes, and carbon dioxide. To remove these elements, several biogas upgrading technologies like water scrubbing, amine scrubbing, pressure swing adsorption, and membrane separation have been developed and are being used at various commercial scales. Problems with these methods are high energy consumption, the use of expensive chemicals, and high operating cost. Therefore, a major effort is currently underway to improve the design of existing methods as well as developing innovative new upgrading technologies such as cryogenic separation and biological upgrading. This review intends to provide a comprehensive overview of the limitations with the existing upgrading technologies along with recent advances in physical, chemical, and biological biogas upgrading technologies (e.g., pressure swing adsorption, membrane separation, biochar adsorption and CO2 conversion by biological organisms) and further into possible future solutions, such as hybrid systems. Comparative studies of process complexities and associated economic concerns are also provided, and future perspectives that may facilitate research into sustainable biogas upgrading technologies are discussed, focusing in particular on cryogenic separation, novel biological techniques, biochar based upgrading and hybrid technologies incorporating two or more different methods seamlessly integrated.

Original languageEnglish
Article number111343
JournalRenewable and Sustainable Energy Reviews
Publication statusPublished - 2021 Oct

Bibliographical note

Publisher Copyright:
© 2021 Elsevier Ltd


  • Biochar
  • Clean energy
  • Renewable energy
  • Sustainable development
  • Waste-to-resource

ASJC Scopus subject areas

  • Renewable Energy, Sustainability and the Environment


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