Quantifying the environmental performance of integrated bioethanol and biogas production

As the production of biofuels continues to expand worldwide, criticism about, e.g. the energy output versus input and the competition with food has been questioned. However, biofuels have the possibility to be optimized in order to improve the environmental performance. This could be accomplished through the use of concepts from industrial symbiosis. This paper provides a quantification of the environmental performance of industrial symbiosis in the biofuel industry through integration of biogas and ethanol processes using a life cycle approach. Results show that although increasing integration is assumed to produce environmental benefits, not all impact categories have achieved this and the results depend upon the allocation methods, energy system and assumptions chosen.

► Integrated ethanol and biogas plants can lead to improved environmental performance.
► Methodological choices for the assessment can influence the results.
► All impact categories should be reviewed to show both global and local impacts.
► Rebound effects may occur by removing some by-products to integrate with biogas plants.
► The energy system and electricity network used for the assessment can influence the results.