Holistic and integrated life cycle sustainability assessment of prospective biomass to liquid production in Germany

As a part of the developing bioeconomy, liquid biofuels may play an important role for transportation due to the hope for a sustainable drop-in alternative to substitute fossil fuels and maintaining existing economic in-frastructures. In this case study we applied Holistic and Integrated Life Cycle Sustainability Assessment to a prospective technical concept for the production of biofuels from wood residues, sorghum and straw via gasi-fication and Fischer-Tropsch synthesis located in the German federal state Brandenburg. Through this quanti-tative and qualitative sustainability assessment we identified synergies and hot-spots of biofuel production on a detailed and aggregated level, as well as compare the impacts to fossil fuels and other alternative transport systems. 99 social, ecological and economic indicator results addressing 14 out of 17 SDGs show contributions but also sustainability risks of such biofuels for the SDGs. The total substitution factor of impacts (f = 21.38) for all indicators of biofuels compared to fossil fuels indicates significantly higher impacts of biofuels production, in particular for land (SDG 15, f = 30.43), water (SDG 14, f = 125.57), consumption and production patterns (SDG 12, f = 54.11), low energy efficiency and maintaining problematic global supply chains and working conditions. However, the impacts on climate can be lower (SDG 13, f = 0.42), if residual heat is effectively and efficiently used. Comparing the transportation systems and use phases of fuels, all types of car-based individual trans-portation including fossil fuels (f = 6.50), biofuels (f = 9.16) and electric drive (f = 6.46) had significant higher impacts than transportation by train. Besides technological downsides, such as the high energy demand, biofuels may play a minor role for specific applications with no other alternative energy technologies in the future. In conclusion, it is very questionable whether such liquid biofuels are a suitable drop-in solution to substitute fossil fuels in a significant quantity. In a final discussion we referred to the necessary societal-ecological transformation with structural changes of production, consumption, political economy and global supply chains. In the future, Holistic and Integrated Life Cycle Sustainability Assessment will be further improved by closing indicator and database gaps, including a cost analysis and direct stakeholder participation, as well as absolute sustainability assessments on how much biofuel production is sustainable.

Automated summary

This study assessed the production of biofuels from wood residues, sorghum, and straw through comprehensive evaluation, and found that biofuel production has greater environmental impacts compared to fossil fuels, particularly on land, water resources, and energy efficiency. However, the impact on climate can be mitigated by effectively utilizing residual heat. Moreover, biofuels may have limited applications in the future. Overall, the suitability of biofuels as a drop-in solution to replace fossil fuels is questionable.