Water scrubbing for biogas upgrading: developments and innovations

Abstract Water scrubbing is a mature and efficient family of methodologies that is already widespread due to its simplicity and generally low costs. This chapter reviews the state of the art of the most common water scrubbing solutions applied to biogas upgrading, focusing on the main advantages (such as low methane loss, energy consumption, and maintenance costs), disadvantages, plant designs, and potential chemical promoters. The subject of methane slip mitigation by water scrubbing is also discussed in detail; indeed, while off-gas carbon dioxide release in the atmosphere can be considered carbon-neutral, methane in off-gas is a strong greenhouse gas, and furthermore its loss is associated with economic loss.