Investigating the use of Ionic Liquids in biogas upgrading

The use of upgraded biogas (biomethane) as vehicle fuel has been considered as one of the most efficient means of utilizing renewable fuels to reduce greenhouse gas emissions from the transpor­tation sector. Although several technologies have been developed and commercialized to upgrade biogas, they are energy intensive and usually require large-scale operations. It thus calls for explor­ing energy and cost effective technologies for biogas upgrading to improve the overall economics of biogas processes.

Ionic liquids have shown great potential to be used as liquid absorbents for CO₂ removal from different gas streams (e.g. biogas upgrading) because of high CO₂ solubility (i.e. high absorption capacity) and low energy requirement for regeneration (i.e. low energy usage and low cost).

A recently finished project within the Swedish Energy Agency and f3 collaborative research program Renewable transportation fuels and systems covers this subject. The project is titled Techno-economic analysis of biomethane production with novel upgrading technology. In the project, both conventional and novel Ionic Liquids (ILs) were chosen as liquid solvents for bio­gas upgrading in order to investigate how the properties of ILs affected the process performance in respect to commercial co-digestion facilities in Sweden and Norway. The performance of the biogas upgrading technology with the ILs was further compared with water scrubbing.

At this point, results from the project can be accessed in a published scientific article, a conference contribution and in a Doctoral Thesis. Publication of the project report has been postponed due to the procedure for scientific peer review of a second article. However, the report can be made available on request from the project leader.