Cost analysis of subcritical water pretreatment of sugarcane straw and bagasse for second‐generation bioethanol production: a case study in a sugarcane mill

Abstract

The value of lignocellulose residues for green technologies has been growing, but biomass pretreatment is still an economic challenge. In this case study, a cost analysis of subcritical water pretreatment (SCWP) of sugarcane by-products for ethanol production was conducted. The proposed industrial scheme is attached to a Brazilian sugarcane mill, which generates a surplus of bagasse. Seven scenarios were simulated to address the prospects of the implementation of the process in the mill. The fermentation of sugarcane bagasse hydrolysate with Scheffersomyces stipitis upgraded the ethanol yield. The fixed capital investment of the industrial process was approximately US$27 million and 35% of this was associated with the SCWP. The highest ethanol yield was obtained for the process operated with hydrolysate from sugarcane bagasse (6740.5 kg ethanol day −1 ), which is associated with the high hemicellulose content in the bagasse composition compared with straw. The cost difference revealed that the fixed capital investment and utilities were the largest expenses for process implementation and operation. The simulated process reached 5.45 US$ L −1 as the lowest cost of manufacturing. However, this cost is approximately 10-fold higher than the market price for ethanol in Brazil. In conclusion, the SCWP of sugarcane straw and bagasse demands significant technical improvement before scaling up to the industrial scale for bioethanol production.

The key role of pretreatment for the one-step and multi-step conversions of European lignocellulosic materials into furan compounds

“…219,221 In subcritical conditions, the pretreatment of lignocellulosic biomass for industrial processes of the order of 310 tons of feedstock daily represents US$ 27.4 × 10 6 of the FC, and 35% (US$ 9.6 × 10 6 ) is associated with the reactor. 219,222 However, in the case of the ILs and DESs, the capital cost of the reactor is expected to be lower than that of supercritical uids and hydrothermal treatment, which require special instrumentation for high temperatures and excessive pressure. 155 OPEX are subcategorized into direct production costs, including raw material, waste steam charges, and xed operating costs, including labor and general expenses.…”

“… 224 For example, the needed heat required for lignocellulosic biomass treatment under these conditions varied between 610 kJ kg −1 225 and 1096 × 10 6 kcal day −1 . 222 However, the hydrothermal process is carried out without using chemicals or catalysts. 219 And among supercritical fluids, scCO 2 presents the lowest cost compared to other supercritical fluids.…”

Sustainable valorization of apple waste in a biorefinery: a bibliometric analysis

“…Hence, methods to reduce, reuse and recycle wastes have become a strong strategy for the circular economy transition of the food industry 4,7 . Thereby, the design of innovative green processes should approach the treatment and valorization of organic waste into low‐GHG products, such as biofuels and bioenergy 8,9 . For instance, consolidated biological waste management technology (i.e.…”

“…4,7 Thereby, the design of innovative green processes should approach the treatment and valorization of organic waste into low-GHG products, such as biofuels and bioenergy. 8,9 For instance, consolidated biological waste management technology (i.e. anaerobic digestion) can feasibly be implemented to convert raw solid organic wastes into methane-rich biogas and fertilizer.…”