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Definition, Calculation and Comparison of the "Biomass Utilization Efficiency (BUE)" of Various Bio-based Chemicals, Polymers and Fuels

Publication date2015

This paper defi nes, introduces and applies a new term, the “Biomass Utilization Effi ciency (BUE)”. This is a new and relatively simple approach to evaluate and compare different bio-based chemicals, materials and fuels based on the input-biomass, the used conversion process and the end product. A BUE analysis can answer the following questions: How effi ciently is biomass utilized? What share of the biomass is ending up in the fi nal product? To summarise the role of the Biomass utilization effi ciency (BUE) in the context of existing methods, it is obvious that this new metric has an emphasis on the best combination of biomass feedstock, process and bio-based product that is absent from existing calculations routinely used by research and process chemists and engineers. At present, waste minimisation during a manufacturing process is addressed through the choice of methods and optimisation of conditions. However, it is now clear that inherent waste, produced by aerobic fermentation for example, is easily overlooked when it concerns the conversion of biomass into chemical intermediates or fuels. Biomass utilization effi ciency (BUE) helps create awareness about alternative approaches for producing bio-based products. The difference in material effi ciency between direct acetic acid production (anaerobic fermentation) and ethanol oxidation is clear (BUEH = 90% compared to 60%). The same also applies to other examples covered in this paper. As demand for renewable resources rises, the effi ciency of (bio)-chemical transformations will come under greater scrutiny. We anticipate the relevance and importance of insightful BUE calculations will increase as the bio-based chemical industry adapts to growing economic and material competition for resources. Finally, this paper shows that it is important to use the right molecule with the right process in the right application. Molecules that havelow oxygen content are more suitable for energetic purposes whereas molecules with higher oxygen content (and additional functional groups) are more suitable to create material with specifi c chemical properties. This oxygen-associated “functionality of biomass can reduce the steps of making a chemical and in that way reduce also the energy needs for the fi nal molecule production” (Diels 2015). To put it differently, the use of oxygenated biomass only makes sense for material use (bio-based products). The only exception might be octane enhancers of the combustion process but those additives can also be grouped under the umbrella of material use of biomass.Even though they were not a part of the scope of this paper, phenolic lignins should also be very suitable to create materials under the points we just mentioned above. Special cases are molecules such as succinic acid, which capture CO2 in their molecular formula. Here, one has the additional, ecological benefit of reducing a greenhouse gas. Moreover, the formula we apply does not take into account that the CO2 created by e.g. making ethanol from biomass could possibly be used to also make value added products like e.g. methane in a biorefinery approach. In some cases a full environmental assessment shows different results. The BUE method does not take into account the energy use and environmental impacts related to bio-feedstock supply.

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Citation (ISO format)
IFFLAND, Kerstin et al. Definition, Calculation and Comparison of the ‘Biomass Utilization Efficiency (BUE)’ of Various Bio-based Chemicals, Polymers and Fuels. 2015
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  • PID : unige:115546

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