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6111039 
Journal Article 
CO2/CH4 separation by hot potassium carbonate absorption for biogas upgrading 
Paolini, V; Torre, M; Giacopini, W; Pastori, M; Segreto, M; Tomassetti, L; Carnevale, M; Gallucci, F; Petracchini, F; Guerriero, E 
2019 
Yes 
International Journal of Greenhouse Gas Control
ISSN: 1750-5836 
83 
186-194 
WOS:000462043400018 
In biogas upgrading to biomethane, the release of CO2 off-gas into the atmosphere is generally regarded as a carbon-neutral emission, but a significant loss of CH4 can occur in this step: considering the global warming potential of this latter compound, methane slip can worsen or even nullify the CO2 savings associated to biomethane. This study investigates a novel approach for biogas upgrading to biomethane, aimed at reducing the methane loss. A plant based on hot potassium carbonate was fed with 150–200 Nm3 h−1 of biogas from municipal waste. CO2 is removed in a K2CO3 absorption column, with negligible CH4 absorption. An assessment of biomethane quality was performed to check its compliance with recent National and European standard specifications. Results show that a methane slip below 0.1% can be achieved with this technology, thus significantly reducing the greenhouse gas emissions associated to biomethane industry. This leads to a lower capital expenditure because no off-gas post-treatment is required. Heat and electricity consumption were monitored, and operational expense resulted to be lower than membrane separation in the specific case study, by applying life cycle cost (LCC) methodology. 
Biogas upgrading; Biomethane; CH4; Water scrubbing absorption; Biofuels