Comparative life cycle assessment of energy and material recovery of cardboard in municipal solid waste

Abstract

Cardboard contributes a large proportion in total MSW and mixed MSW. Recovery of cardboard, either as material or energy, is believed to reduce the impacts on the environment from the global warming point of view. European Union has been promoting recycling which resulted in recycling of the majority of well-separated cardboard. Published life cycle assessment studies show that recycling can provide the best benefits to the environment. However, some other studies argue that incineration with energy recovery would bring more credits. The technological data and system boundaries of the studies were proved to affect the outcome of the recovery methods studied.

The present thesis was carried out assuming high technology data for both recycling and incineration with energy recovery. The main focus was on global warming potential (GWP), but also acidification (AP) and eutrophication potentials (EP) were taken into consideration. Results of all three impact categories supported the option of energy recovery had higher benefits compared to material recovery. Even though recycling could reduce the environmental burdens in GWP, this method resulted in additional impacts on AP and EP. Full replacement of virgin fibers could offer better results than partial substitution for GWP but it was opposite for AP and EP.

Sensitivity analysis supported the superiority of energy recovery as the recovery method always reduced GWP, AP and EP. Performance of the recycling was not as steady as energy recovery. When electricity from natural gas or grid mix was substituted, energy recovery provides lower savings than in the baseline scenario.