CARBONIZATION OF SPENT COFFEE GROUNDS: A PATHWAY TO HIGH-ENERGY BIOMASS PELLETS
DOI:
https://doi.org/10.11113/aej.v15.23496Keywords:
Solid fuel, Biomass pellet fuel, Energy properties, Heating valueAbstract
This research investigates the use of spent coffee grounds (SCG) for producing pellet fuel (PF), with a focus on enhancing their energy properties through carbonization. Thermogravimetric analysis (TGA) was employed to determine the optimal carbonization temperatures. Three types of SCG samples were prepared for pelletization: (1) Dry spent coffee grounds (DSCG), (2) Carbonized spent coffee grounds at 250 °C (CSCG250), and (3) Carbonized spent coffee grounds at 350 °C (CSCG350). The pellets were formed using a custom-built single pellet press, utilizing a cold pressing technique with tapioca starch as a binder. The physical properties (length, diameter, durability index, bulk density, and weight) and fuel properties (moisture content, ash content, volatile matter, fixed carbon, and heating value) were analyzed in accordance with ASTM (American Society for Testing and Materials) standards. The analysis showed that the length, diameter, durability index, bulk density, and ash content of all three pellet types met established biomass pellet standards. However, moisture content analysis revealed that DSCG-PF and CSCG250-PF exceeded the standard threshold, likely due to the cold pressing technique, which does not reduce moisture content. Although sun-drying was employed post-production, the resulting moisture levels were inconsistent. Nonetheless, the residual moisture did not significantly impact fuel quality. The heating value analysis revealed a substantial increase from 21.9 MJ/kg in DSCG-PF to 30.9 MJ/kg in CSCG350-PF, representing a 40.1% improvement. All pellet types met the standard heating value criteria, with CSCG350 displaying the most favorable energy properties. The production of pellet fuel from SCG presents an effective solution for coffee waste management. Furthermore, the carbonization process substantially enhances the fuel properties and heating value of the resulting pellets, with the CSCG350 sample showing the most promising results. Therefore, producing SCG into pellet fuel is another good way to solve the problem of SCG waste. The carbonization process is a way to make the fuel properties and heating value of the pellets more efficient. This research contributes to the development of sustainable, high-efficiency biomass fuels from SCG, while addressing the issue of coffee waste disposal.
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