CO2 and H2H cryogenic removal process evaluation for the biogas upgrading and liquefaction.

At present there is an increasing focus on environmental issues and air pollution. Although several measures were taken to reduce greenhouse gas (GHG) emissions, major efforts will be necessary in order to comply with the European climate targets. In this context, the transport sector accounts for almost a quarter of the global GHG emissions. Several studies demonstrate that natural gas (NG) could efficiently substitute conventional fuels, reducing the environmental impact. In particular, its liquid form (LNG) presents additional advantages, due to its high energy density. Recently, an interesting opportunity in this way was found in using purified biogas as feedstock gas, namely biomethane. In order to obtain such a gas, H2S and CO2 have to be removed from biogas. Actually, several upgrading and purification technologies are available but, to produce LNG, cryogenic upgrading technologies become very interesting. Purpose of this study is to investigate the possibility to remove H2S and CO2, obtaining liquefied biogas (LBG), with a single plant. The analysis is performed by means of HYSYS software. An economic comparison between this technology and conventional systems and between this technology and another cryogenic upgrading method is also performed. Results indicate that the proposed technology is a valid option for LBG production.