Techno-economic learning in biorefinery research; a meta-level perspective of three exemplary cases

The production of liquid fuels and chemicals from biomass is an essential part of establishing a bioeconomy. Numerous techno-economic studies have been published on different pathways for processing biomass. To examine the progress made in this field, a meta-analysis investigating three exemplary biobased products was conducted. Using recently published techno-economic studies, the (average) unit production costs for biodiesel, cellulosic ethanol and kraft lignin were investigated. Findings in this study are based on an understanding of two phenomena: economies of scale and the learning effect. Economies of scale can be observed for each case, with kraft lignin extraction indicating the greatest cost advantages and the production of biodiesel the smallest. The investigation of potential learning effects revealed by the data yielded unexpected results: In two out of three cases, the calculated average unit production cost was observed to increase over time. These results contradict the expected influence of learning effects on calculated unit production costs as these did not decrease over time for a specific technology. A closer investigation of processing pathways and feedstocks shows that a diversification in research has occurred over the last three decades. Different driving forces of innovation related to the investigated products are also identified.