Methane loss from commercially operating biogas upgrading plants

•Methane emission from nine biogas upgrading plants has been measured.•State-of-the-art of the methane emission from biogas plants has been summarized.•Regenerative thermal oxidizer was tested to minimize the methane emission. Biogas technology is one of the widely applied anaerobic digestion approaches to harvest methane from different wastes. Recently, methane loss from biogas plants and its environmental and economic consequences have been underlined, but not thoroughly researched. In this investigation, process related CH4 loss from nine different commercially operating biogas upgrading plants such as water scrubber, amine, and membrane-based plants was examined. The result of the measurements showed an average of 0.81% methane loss with respect to supplied methane to the upgrading plants. A methane loss up to 1.97% was detected in water scrubber methane upgrading technology and up to 0.56% loss from membrane technology, while 0.04% methane loss was detected in amine based upgrading, thus the water scrubber has shown the most detrimental effect as regards methane loss. The regenerative thermal oxidizer was further applied to reduce CH4 emission by 99.5% of the amount of CH4 in the waste gas from the upgrading unit, which ensures the sustainable process of biogas production.