Biogas Upgrading Technologies: State of Art Review in European Region

Upgrading biogas to high energy biomethane is commonly utilized to produce SNG (substitute natural gas used for injecting into grid) and/or CNG (compressed natural gas employed as a fuel in transportation). In this process the most crucial operation is a separation of CO2 from biogas, which is carried out by technology based on unit operations like absorption or permeation. Aim of this text is to introduce state of art in development of these technologies within European region: assess their pros and cons in order to alleviate orientation in this issue and point out research tendencies. There were chosen three aspects for the assessment: (1) process-technology, (2) energy-economy and (3) environmental impact. The review is based on research of studies, reports and other informational sources that come from the work of some research institutions and engineering companies. From process-technology perspective specifications like methane purity and flow rate range were evaluated. Aspect regarding energy and economy is mainly focused on assessment of consistency of available data and on utilization of the data for comparative analysis of given technology. From environmental point of view there was considered an important specification called methane losses. The review clearly suggests that in European region the highest share refers to water scrubbing technology which is followed by PSA method and chemical absorption. All kinds of absorption technology (water scrubbing, absorption with chemical or physical solvents) seem to be well established and conventional. On the other hand PSA method and especially membrane technology offer progressive research potential.