Techno-economic analysis and life-cycle assessment of pyrolyzed hydrochar production from waste corn stover

Corn stover, an abundant agricultural residue, represents a significant untapped resource for producing value-added materials through thermochemical conversion. Pyrolyzed hydrochar, a promising carbon-rich adsorbent whose performance is subjected by pyrolysis conditions. Attention should be made on the large-scale viability of production of this adsorbent focused on the economic competitiveness and environmental performance relative to current waste management protocols. This study addresses these considerations by evaluating the TEA and LCA of pyrolyzed hydrochar production for a basis of 500 tonnes per day of waste corn stover biomass. Three different cases were studied at varying pyrolysis temperatures (Case I = 400 °C, Case II = 600 °C, Case II = 800 °C), as studies have shown a direct correlation between adsorbent quality and pyrolysis temperature. The results indicate that Cases I-III achieved break-even within 2, 3 and 3 years, respectively. Correspondingly, the return on investment (ROI) values were 7.82, 3.24, 2.31 for Cases I, II, and III respectively. The sensitivity analysis reported the pyrolyzed hydrochar selling price, moisture content of corn stover, and cost of feedstock were the most significant parameters with major deviations in the ROI for all cases. To evaluate environmental impact a gate-to-gate life cycle assessment, using the ILCD 2011 Midpoint + method was utilized for the same process. The results showed that Case I with heat integration, involving heat exchange between the pyrolysis furnace and dryer, demonstrated the best environmental performance. The pyrolyzed hydrochar production process outperformed open field burning of corn stover for most of the impact categories, achieving a notable 40.68% reduction in greenhouse gas emissions. Hotspot analysis identified the HTC reactor as the primary contributor to several impact categories, including acidification, freshwater ecotoxicity, marine eutrophication, human toxicity, and photochemical ozone formation. The industrial production of pyrolyzed hydrochar demonstrates positive return on investment potential along with environmental sustainability offering a promising solution for resource-efficient management.