Upgrading of biogas using ash

In order to be able to use biogas as a vehicle fuel it needs to be purified so that the methane share is increased whilst the carbon dioxide share is reduced. When biogas pass through a container with ash its methane share will increase whilst the carbon dioxide share will be reduced. Through a number of processes the carbon dioxide in the gas and the calcium oxide in the ash produce calcium carbonate, i.e. lime stone. A number of projects have aimed at making the process applicable for biogas upgrading:

• In the project "Upgrading of biogas using bottom ash from woodfuels" the purpose was to study the process in labscale using woodfuels and Salix
• In the project "Optimized uptake of carbon dioxide from biogas using calcium-rich ash" lab trials are used to study how gas flow rates, ash humidy as well as ash bed dimensions influence the capacity of the ash bed to bind carbon dioxdide.
• In 2014 pilot scale trials at Lövsta biogas plant will take place, as part of the SE Biomethane project, which is financed by the Swedish Energy Agency through EN ERA-NET Bioenergy.