Abstract
As of 2023, the production capacity of medium chain carboxylates (MCCs) from traditional feedstocks (palm and coconut oils) could only meet 1% of market demands. Consequently, alternative production of MCCs from waste streams have been investigated by several authors. However, the sustainability of producing MCC from waste streams has received minimal attention. One way of measuring the sustainability of MCCs production from waste biomass is through a techno-economic analysis. The objective of this study was to evaluate the economic feasibility (or otherwise) of MCCs production from the fermentation of 10 million tons per year of ensiled sugar beet leaves using appropriate economic indicators; the net present value (NPV) and the profitability index (PI). In doing so, two different scenarios were explored. In the first scenario, only the production of MCCs was considered. In the second scenario, an integrated biogas plant was added to the process to further utilize the waste streams from the fermentation process. Results showed that in the first scenario, the NPV and PI were -€506.96 million and 0.60 respectively. In the second scenario, the respective economic indicators were €214.99 million and 2.54. What these results mean is that unless the waste streams from the fermentation process is further used for biogas production, MCCs production from ensiled sugar beet leaves is not economically viable. However, with an integrated biogas production, there is an indication of economic competitiveness. This research shows, for the first time, a techno-economic evaluation of MCCs production from ensiled sugar beet leaves.

Key words: Anaerobic fermentation, Biorefinery, Caproate, Electron donors, Lactate, Microbial chain elongation, Waste biomass