The production of muconic acid and butyric acid from sugarcane molasses and lignocelluloses: A techno-economic comparison of biorefinery scenarios

Developing biorefineries for biofuels and biochemicals presents technical challenges related to energy demands and technology performance, which influence production costs, profitability, and greenhouse gas (GHG) emissions. The demand for bio-based carboxylic acids, such as cis, cis-muconic acid (ccMA) and butyric acid (BA), is increasing as sustainable alternatives to fossil-based products, with a target market price of approximately $1700/t. This study conducted a techno-economic analysis of eleven biorefinery scenarios integrated with an existing sugarcane mill using Aspen Plus simulations. Mass and energy balances informed equipment sizing, costing, and GHG emissions. A discounted cash flow method was used to assess profitability and determine the minimum selling price (MSP) required to achieve a 20 % internal rate of return (IRR). The most economically attractive scenario involved producing 8.9 t/h of BA from A-molasses (1 G) with green hydrogen as a by-product, achieving an MSP of $1416/t and a 75 % emission reduction (0.99 kg CO₂eq/kg BA). In contrast, ccMA production from A-molasses was economically unviable, with an MSP of $2364/t and a production rate of 6.15 t/h, despite its lower energy demand. Integrating lignocellulosic sugars (2 G) with A-molasses for BA and ccMA production via solubilised lignin yielded an MSP of $1935/t and the lowest emission factor (0.03 kg CO₂eq/kg), corresponding to a 98 % emission reduction. These results highlight that integrating 1 G and 2 G feedstocks can substantially reduce GHG emissions while improving the economic feasibility of bio-based chemical production compared to using 1 G feedstock alone. • Regenerative reagents cut production costs by 20 % in 1 G butyric acid biorefineries, improving economic viability. • Selling green hydrogen, instead of using it for boilers, lower the minimum selling price by 9 % in 1 G configurations. • Lignin utilisation in 1G2G ccMA biorefineries increased production by 13 % and reduced GHG emissions by 99 %, yielding the best outcome. • Co-producing ccMA and BA from 1G2G feedstocks lacked economic advantages over BA-only scenarios due to high operating expenses. • Restricted use of regenerable reagents in ccMA recovery circuits limits economic viability, thus highlighting the need optimise the process.