This chapter describes the development of industrial-scale process designs for fermentation, anaerobic digestion, and transesteri‚cation processes for the production of chemicals from biomass. The chemicals produced from biomass were ethanol from corn and corn stover, fatty acid methyl ester (FAME) and glycerol from transesteri‚cation, acetic acid from anaerobic digestion, syngas from gasi‚cation of biomass, algae oil production, ethylene from ethanol, and propylene glycol from glycerol. The corn stover fermentation process, acetic acid process, FAME and glycerol process, propylene glycol process, and ethylene from ethanol process were designed in Aspen HYSYS®. The process cost estimation for these processes were made in Aspen ICARUS®. The corn ethanol process model was based on the USDA process for dry-grind ethanol, and the process model was obtained in SuperPro Designer® from Intelligen Inc. (Intelligen, 2009). The models for algae oil production and gasi‚cation of biomass processes were black box models since there was limited knowledge of processing details.