Gasification of fruit wastes and agro-food residues in supercritical water

• Published in: Energy conversion and management 2016-02, Vol.110, p.296-306
• Main Authors: Nanda, Sonil, Isen, Jamie, Dalai, Ajay K., Kozinski, Janusz A.
• Format: Article
• Language: English
• Subjects: Agro-food residues; Aloe vera; Feed concentration; Fruit wastes; Fruits; Gasification; Hydrogen; Management; Musa; Reaction time; Residues; Selectivity; Supercritical water gasification; Temperature; Wastes
• ISSN: 0196-8904; 1879-2227
• DOI: 10.1016/j.enconman.2015.11.060

[Display omitted] •Supercritical water gasification of various fruit wastes and agro-food residues.•Coconut shell had superior carbon content and calorific value due to high lignin.•Maximum H2 yields at 600°C with 1:10 biomass-to-water ratio, 45min and 23–25MPa.•High H2 yields from coconut shell, bagasse and aloe vera rind with 2wt% K2CO3.•High CH4 yields from coconut shell with 2wt% NaOH due to methanation reaction. Considerable amounts of fruit wastes and agro-food residues are generated worldwide as a result of food processing. Converting the bioactive components (e.g., carbohydrates, lipids, fats, cellulose, hemicellulose and lignin) in food wastes to biofuels is a potential remediation approach. This study highlights the characterization and hydrothermal conversion of several fruit wastes and agro-food residues such as aloe vera rind, banana peel, coconut shell, lemon peel, orange peel, pineapple peel and sugarcane bagasse to hydrogen-rich syngas through supercritical water gasification. The agro-food wastes were gasified in supercritical water to study the impacts of temperature (400–600°C), biomass-to-water ratio (1:5 and 1:10) and reaction time (15–45min) at a pressure range of 23–25MPa. The catalytic effects of NaOH and K2CO3 were also investigated to maximize the hydrogen yields and selectivity. The elevated temperature (600°C), longer reaction time (45min) and lower feed concentration (1:10 biomass-to-water ratio) were optimal for higher hydrogen yield (0.91mmol/g) and total gas yield (5.5mmol/g) from orange peel. However, coconut shell with 2wt% K2CO3 at 600°C and 1:10 biomass-to-water ratio for 45min revealed superior hydrogen yield (4.8mmol/g), hydrogen selectivity (45.8%) and total gas yield (15mmol/g) with enhanced lower heating value of the gas product (1595kJ/Nm3). The overall findings suggest that supercritical water gasification of fruit wastes and agro-food residues could serve as an effective organic waste management technology with regards to bioenergy production.