Abstract
Global concerns about mitigation of greenhouse gas (GHG) emissions and enhancement of energy security has grown rapidly over the years. Therefore, it is important to investigate new renewable energy sources. Biomass is considered as one of them, it can be used for fuels and chemicals production. However, its application should be efficient and flexible, that is why biorefinery concept was proposed.
This study was aimed to determine the most sustainable way of bioethanol and bioplastic co-production based on literature review. To evaluate environmental performance of defined biorefinery system life cycle assessment (LCA) was used.
Results of LCA suggested, that production of HDPE in thermo-chemical biorefinery from poplar wood/forest residues has remarkably lower environmental impact than HDPE, obtained via fermentation from sugar beet. Reductions were also noted in such categories as global warming and fossil resource depletion, when thermo-chemically produced HDPE was compared to its fossil equivalent. However, switch from crude oil to biomass indicated an increase of impact in eutrophication and acidification. Comparison of poplar wood and forest residues as raw material for biorefinery showed, that forest residue is the best option, since its use minimized impact across all categories considered, and compared to fossil-based HDPE it has lower eutrophication potential. Therefore, it was concluded, that use of biomass should minimize contribution not just to global warming and fossil resource depletion, but to other impact categories as well, in order to avoid shift in pollution.
Another key finding of this thesis indicated the importance of accounting for biogenic carbon. In the program used for LCA biogenic carbon, which is emitted during the production of biobased HDPE and bioethanol, assumed to be neutral. Hence, it’s contribution to GWP wasn’t taken into account, what has led to unfair comparison between oil and biorefinery.
