Effects of cultivation period on catch crop chemical composition and potential for bioenergy production

The first step in biofuel and/or bio-based bulk chemical material production is assessing the amounts of useful substances in a potential biomass. Sugar, nutrients, ash, and functional ingredients (such as antioxidant compounds) in premature dent corn biomass cultivated as a catch crop (plant density; 60 shoots m⁻²) over different cultivation periods (29 days, 49 days, 83 days) were investigated. The sugar recovery amount was estimated by multiplying two regression curves (saccharification efficiency curve, quadratic regression curve; dry weight growth curve, Gompertz curve). A simple economic analysis for ethanol production from the catch crop biomass was also carried out using previously reported process costs and the estimated sugar recovery amount. High plant density led to accumulation of plant biomass providing high amounts of plant dry weight and derived sugars per unit area. About 2700 g DW m⁻² (about 1400 g sugar m⁻²) was harvested in the 49-day cultivation. The amount is significant compared with biomass yields of other candidates for energy crops. The estimated sugar recovery amount reached its maximum value near the end of experimental period (79-day cultivation). The longer cultivation period was better for sugar recovery although there was a slight decrease in saccharification efficiency with cultivation time. Based on the economic analysis, a higher ethanol price (about 200% higher than the current wholesale price) would be required for catch crop financial independence with around 50-day cultivation. Production of ethanol from catch crop biomass would not be feasible in the current situation. However, condensed biomass production through catch crops is still attractive and requires further research.