Biofuel production from citrus wastes: A feasibility study in Iran

Biomass is a major energy source accounting for 10-14% of the world's energy supply. Citrus is one of the most important horticultural products in Iran. Annually, a great amount of wastes are produced due to food processing plants, lack of appropriate conditions for maintenance, and an insufficient citrus processing industry in Iran. These wastes are often disposed of in landfills or used as animal feed. Citrus waste (CW) contains various polymers of soluble and insoluble carbohydrates that are the ideal raw material for conversion into biological biofuels such as ethanol and biogas. In 2014, the cultivation area (including non-fertile and fertile areas) of horticultural products was approximately 2.59 million hectares in Iran. The citrus production in the same year was 4,320,041.29 t. The highest citrus production is in Mazandaran Province, followed by Fars and Kerman provinces. Approximately 1,265,975.95 t of this product are processed in the processing industry as a low-grade product, where citrus fruits create 682,987.97 t of wastes. The results showed that the wastes produced from citrus have a good potential for biofuel production in Iran. The ethanol and biogas produced from CW is estimated to be 26.98 million liters and 37.08 million m3, respectively. Iran has also a potential of producing 93277-179283 t of bio-oil.