Commodity chemical production from third-generation biomass: a techno-economic assessment of lactic acid production

The unique characteristics and composition of macroalgae offer new possibilities for the production of bio-based products such as biofuels and commodity chemicals. The technologies required for processing macroalgae are not currently mature enough, and those that exist are primarily oriented towards the production of biofuels. This study explores a production process to produce lactic acid (LA) from brown algae, designed with a capacity of 11 t h⁻¹ of product. Four scenarios are simulated in Aspen Plus, for the production of polymer-grade LA, utilizing Laminaria macroalgae as a feedstock. Techno-economic models are established to investigate the feasibility of these new technologies. Configurations for heat recovery are suggested to maximize productivity, and a minimum viable selling price (MVSP) is calculated for LA to predict an optimal design configuration. The process does not recover investment, when using a composition represented by an avarage value for all the Laminaria sp. Moreover, the percentage difference between the MVSP and the current selling price (SP) is 34%. Nonetheless, when using Laminaria digitata, which comprises of higher carbohydrates, compared to other Laminaria sp, the percentage difference between the MVSP and the SP is estimated to be 28%. If the hypothetical fermentation of alginate is considered, the invested capital is recovered by the 11th year. These results also highlight the need for research into the valorization of the alginate fraction, improving the microorganisms’ ability to metabolize alginate to LA or other relevant products. The development of the respective processes would be a step that the scientific community would be justified in examining.