Chemical building blocks from lignocellulosic feedstock form a huge potential for the production of bioplastics. More specifically, they have potential for biodegradable plastic poly(lactic acid) (PLA). The building block for PLA – lactic acid – is currently produced mainly from starch originating from corn, or sugar from sugarcane. A sustainable and cost-effective production process for lactic acid on a scale that meets future demands requires the use of second generation biomass such as lignocellulose. Wageningen UR Food & Biobased Research studies the process from lignocellulosic feedstock to lactic acid.
To get a clear view on the availability of agricultural residues for lactic acid production, Food & Biobased Research is performing a biomass availability study. We also carry out research into the pretreatment of lignocellulose for the production of lactic acid in order to define in-depth information about processing options.
Availability of lignocellulosic biomass
The overall objective of the biomass availability study is to assess the worldwide availability and suitability of agricultural residues for lactic acid production based on the fermentation of carbohydrates. The study focuses on lignocellulosic biomass that is produced as a by-product of agricultural production. The results of this study can be used to rank different biomass types for their lactic acid or fermentable sugar production potential. It can also be used to further evaluate the suitability, cost and sustainability of agricultural residues as feedstock for lactic acid fermentation or other biochemical conversion processes.
Review of pretreament options
The research review on the pretreatment of lignocelullose for the production of lactic acid will provide in-depth information on the processing options. In an ideal situation, the pretreatment will lead to a high yield of fermentable sugars that can be fermented to lactic acid in a cost-effective manner. This implies limited formation of degradation products that might inhibit enzymatic and fermentation processes. The review deals with these challenges by providing information on available pretreatment technologies in general and on the model feedstock sugarcane bagasse in particular. A techno-economic study is included.
Further research needed to realise cost reductions
The costs of lignocellulose can be reduced by focussing on increasing the amount of sugars produced per ton of biomass. Another strategy is to focus on low cost biomass such as residues that have negative or zero value, or biomass streams that bear no logistic costs. Pretreatment has been recognised as one of the most expensive processing steps in the conversion of lignocellulose to fermentable sugars. The key question in the assessment and comparison of different pretreatments is the resulting sugar concentration and the optimal concentration for fermentation to lactic acid. Which pretreatment may lead to the highest sugar concentration is a remaining research question that is subject to further experimental research within the BE-Basic programme.