Techno-economic assessment of densified Arabica coffee pulp pyrolysis in a pilot-scale reactor

A continuous rise in coffee bean production consequently generates more coffee pulp, one of the main biomass residues from coffee cherry processing which has not been yet utilized effectively. The use of this biomass type is quite challenging due to its low energy and high water content. Therefore, this research aimed to develop an effective strategy for coffee pulp pyrolysis by increasing the feedstock density. During this investigation, three kinds of pyrolysis experiments were performed, including pyrolysis of densified coffee pulp at a temperature of 300 °C, 400 °C, and without densification at 400 °C. The economic analysis was carried out using the NPV approach in place of the reactor performance and product analysis. Based on experimental results, the densification of coffee pulp is useful in increasing production capacity up to three times as well as reducing the fuel consumption from 1.47 kg LPG/kg feedstock (without densification) to 0.46 kg LPG/kg feedstock. The research showed that the bio-oil yield was 51% higher in the pyrolysis of densified coffee pulp at 400 °C and while at 300 °C producing 42% of bio-oil. Meanwhile, regarding the properties of biochar, increasing the pyrolysis temperature from 300 to 400 °C caused a significant increase in the fixed carbon content, i.e., from 37.82 to 54.98%, and the calorific value of 6061 to 6354 cal/g. The NPV calculation results show that pyrolysis of compacted coffee pulp at a temperature of 300 °C is more feasible than other methods.