Techno‐economic analysis for hydroxy acids production from waste cellulose via alkaline digestion

Abstract BACKGROUND Alkaline digestion offers a promising route for converting low‐grade cellulosic wastes into valuable hydroxy carboxylic acids (HAs). However, the feasibility of producing HAs at process scale, particularly the influence of reactor design on product yields, energy demand, and production costs, remains less explored. This study integrates a detailed kinetic model with process simulation to evaluate techno‐economic performance of three process options that differ in reactor configuration and operating temperature. RESULTS The batch reactor with a temperature profile (BR‐TP) showed the highest selectivity toward glucoisosaccharinic acid (GISA), reaching approximately 65% of total HAs at target temperature of 200 °C, whereas the isothermal batch (BR‐IsoT) and isothermal CSTR (CSTR‐IsoT) favored smaller hydroxy acids (SHA). The CSTR‐IsoT offered shorter residence times at moderate conversions but required dramatically longer times at high conversions; at 200 °C, achieving the target conversion required 38‐fold longer time compared with BR‐TP. Techno‐economic analysis identified BR‐TP‐200 with the lowest total production cost (TPC) at 0.532 €/kg of product. In contrast, CSTR‐IsoT‐200 exhibited the highest TPC (0.928 €/kg). Energy consumption varied from 3.93 kW/kg of product in the BR‐TP (lowest) to 5.1 kW/kg of product in the CSTR‐IsoT. Sensitivity analysis confirmed raw materials as the dominant contributor to cost variability, while utility price fluctuations had minimal effects. CONCLUSION Batch operation, particularly BR‐TP, delivers the most favorable trade‐off between selectivity, energy use, and production cost, confirming the feasibility of alkaline digestion for HAs production. Future studies should validate the model with real wastes and develop improved reactor and alkali‐recovery strategies for scale‐up. © 2026 The Author(s). Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).