Assessment of spent coffee ground (SCG) and coffee silverskin (CS) as refuse derived fuel (RDF)

Abstract

The implementation of waste into energy can be a solution for waste coffee handling. The mixture of spent coffee grounds (SCG) and coffee silverskin (CS) has the potential to produce better fuel. This study aims to determine the characteristics of SCG and CS and the effect of mixing SCG and CS on the quality of pellet fuel produced. Characteristics of SCG and CS as refuse derived fuel (RDF) include density, morphology, particle size distribution, parameters in biopolymer analysis, proximate and ultimate analysis. A densification method with a pressure of 195 MPa is used in the pellet-making process. Characteristics of pellet fuel analyzed include density, durability, proximate analysis, calorific value, and combustion testing. The results showed that the physical characteristics of CS were suitable for producing pellets with better density, durability, and combustion levels, but large amounts of CS in pellets potentially produce particulate and NOx emissions during combustion. Samples with a mixed composition of SCG, CS, and artificial adhesives are 75%, 20%, 5%, respectively, resulting in optimum quality pellets which conform to several parameters of the German pellet standard DIN 51731.