Background Greenhouse gas (GHG) emissions from the waste management sector account for around 3% of total emissions in the EU (2006 data). Emissions in the waste management sector are primarily a result of methane emissions from landfills, caused by the anaerobic break down of biodegradable materials. Methane emissions from the waste management sector fell by 39% between 1990 and 2006. Total greenhouse gas emissions from this sector are projected to decrease further, to approximately 44% of 1990 levels by 2010. The decrease is mainly a result of the implementation of the EU Landfill Directive and similar national legislation, which reduces the amount of untreated biodegradable waste disposed of in landfills and installs landfill gas recovery systems at all new sites. A further reduction in CO2 emissions from landfill sites would however contribute to additional reductions in greenhouse gas emissions. The CO2 contained in landfill gas/biogas is of biogenic origin, and its emission does not effectively contribute to the greenhouse effect balance. If CO2 is captured from the landfill gas/biogas and stored, it would be possible to obtain an additional reduction in CO2 in the atmosphere, sinking the overall greenhouse effect balance. Objectives The overall objective of the ‘UPGAS-LOWCO2’ project was to reduce the landfill gas emissions and thus their contribution to the greenhouse effect. This would be achieved through the implementation of two methods. The first proposed method was based on the chemical absorption of CO2 with an alkaline aqueous solution that produces carbonate-rich solutions. This spent solution is fed to a regeneration step, where it is mixed with alkaline industrial residues (such as fly or bottom ashes, steel slag and cement wastes), producing a sludge rich in calcium or magnesium carbonate and a regenerated alkaline solution, that is recycled to the absorption column. The second method was based on the chemical reaction between gas containing carbon dioxide and bottom ash (BA). This kind of process accelerates the carbonation of the solid residues and CO2 uptake. Results The UPGAS-LOWCO25’ project designed, constructed and demonstrated two innovative systems for the removal and capture of CO2 from landfill gas/biogas. These processes increased the quality of landfill gas/biogas to that of natural gas. An integrated pilot plant for CO2 absorption and the regeneration of the spent solution with CO2 storage was designed and built in order to demonstrate the technical feasibility of the proposed processes. The two processes reached high methane purity (>90% vol.) and thus can produce bio-methane for grid injection or fuel. Further, the processes lead to less metals being released from air pollution control (APC) or BA from waste incineration if they come into contact with water. The cost of disposal for APC is reduced, whilst for BA it is cancelled and money can be earned from selling the material obtained to the construction sector. The project carried out a lifecycle assessment, which showed several environmental benefits from the use of these two technologies. Extensive application is, however, limited by the availability of solid residues and suggested application should occur at sites that have a residues and biogas producer (incinerator and landfill or anaerobic digestion plant). Further information on the project can be found in the project's layman report and After-LIFE Communication Plan (see "Read more" section).