Apr 9, 2007

EU looks at feeding biogas into the main natural gas grid

The biogas sector is undergoing a rapid transformation in Europe. Whereas green gas production used to be an activity associated with individual farms and community waste management programs, it has been scaled up to become an industry that produces quantities large enough to be fed into the main natural gas grid. More and more, dedicated biogas crops (such as specially bred biogas maize, exotic grass species such as Sudan grass and sorghum, or new hybrid grass types) are being utilized as single substrate feedstocks for large digester complexes, and biogas upgrading to natural gas standards is becoming more common.
Upgrading biogas to NG quality
A key technology for injection of biogas into the natural gas grid is upgrading of the biogas to natural gas quality after which it can be compressed to transport grid pressure. Biogas consists of around 50 to 65% of methane, small fractions of other compounds and 50 to 35% of carbon dioxide, which has to be removed before injection. (Earlier we pointed out why this large CO2 fraction makes pre-combustion carbon capture from biogas an interesting option in the context of carbon capture and storage, which results in the concept of a radical carbon negative energy system - previous post).