Statistical optimization, characterization and effect of process variables on cotton stalk pellets using tractor...

Area of Science:

• Agricultural Engineering
• Renewable Energy
• Biomass Conversion

Background:

• Cotton stalk is an abundant agro-residue in Southern India with significant bioenergy potential.
• Electricity shortages in Southern India necessitate sustainable energy solutions.
• On-field processing of agro-residues can reduce transportation costs and enhance energy generation.

Purpose of the Study:

• To develop and characterize an energy-efficient, portable tractor Power Take-Off (PTO)-based pelleting machine for cotton stalk.
• To evaluate the performance and economic feasibility of the developed pelleting machine.
• To analyze the physicochemical properties of cotton stalk pellets for bioenergy applications.

Main Methods:

• Development of a tractor PTO-operated pelleting machine for on-field operation.
• Utilization of Box-Behnken design with Response Surface Methodology (RSM) for performance evaluation.
• Comprehensive characterization of cotton stalk pellets including proximate, ultimate, physical, TG-DTG, FTIR, and SEM analyses.

Main Results:

• The pelleting machine achieved 87.06% efficiency and 42.65 kg/h capacity with a bulk density of 614.09 kg/m³.
• Cotton stalk pellets exhibited favorable properties: 2.73% ash, 18.92 MJ/kg calorific value, 92.80% shattered index, and 93.75% durability.
• Economic analysis indicated a benefit-cost ratio of 1.11 and a payback period of 33.1 months, with a 74% internal rate of return.

Conclusions:

• The developed tractor PTO-based pelleting machine is an effective and economically viable solution for converting cotton stalk into bioenergy.
• Cotton stalk pellets possess suitable characteristics for efficient combustion and energy generation, addressing regional electricity shortages.
• On-field pellet production minimizes logistical costs and promotes sustainable agro-residue utilization in Southern India.