Combustion characteristics of densified bio-char produced from Gayo Arabica coffee-pulp: Effect of binder

Abstract

Increasing number of coffee-by-products highlights its potential as source of renewable energy. The use of coffee pulp as a raw material for bio-briquettes is considered as an effective way to minimize their wastage as landfill. This study aims to examine the combustion characteristics of bio-briquettes produced from Gayo Arabica coffee-pulp which was carbonized through a slow pyrolysis process and densified at a pressure of 150 kg/cm2. Prior to densification process, the raw material was sun-dried, pyrolyzed, ground and sieved to mesh 20. A mixture was then made by adding starch binder at 20, 30 and 40 wt.% followed by molding and drying processes. Characterization of the briquette employs a number of techniques including DSC, bomb calorimeter and proximate analyses as well as combustion test. The results show that the amount of starch-binder significantly affects the rate of combustion and the flame duration. However, no significant change is found in term of calorific value, moisture and ash content.