Comparative Life Cycle Assessment and Costing of Biogas Direct Methanation and Water Scrubbing Upgrade

Biogas CO2 content can be valorized directly through the methanation process without the need for a cleaning step. By integrating biogas production with a methanation system, a net increase in biomethane yield and productivity can be achieved while reducing greenhouse gas emissions. This study aims to compare the environmental and economic performances of a biogas direct methanation system to those of one of the most widely-used conventional methods, namely water scrubbing, by means of Life Cycle Assessment and Life Cycle Costing methodologies, with specific reference to the Campania region context. Two detailed models were developed using Aspen Plus to produce high-purity methane suitable for direct injection into the natural gas grid. From simulations, inventory data of plant operations are collected and used for environmental and economic assessments. While direct methanation presents higher environmental impacts under current energy scenarios, utilizing renewable energy sources can substantially mitigate these impacts. Similarly, direct methanation becomes a cost-effective alternative to water scrubbing if a surplus of wind energy provides hydroge