KARAKTERISTIK DAN KINETIKA PEMBAKARAN CO-FIRING HYDROCHAR BATOK KELAPA TERAKTIVASI NaOH DAN BATU BARA SUB BITUMINUS

Abstract

The utilization of biomass as a co-firing fuel alongside coal is a strategy to support the energy transition and reduce carbon emissions in coal-fired power plants. Coconut shells hold potential as a biomass source that can be converted into hydrochar via Hydrothermal Carbonization (HTC) and subsequently upgraded through chemical activation with an NaOH solution. This study aims to examine the effect of NaOH activation on the combustion characteristics and kinetics of coconut shell hydrochar used in a co-firing system with sub-bituminous coal. Analyses were conducted using Thermogravimetric Analysis (TGA) and Derivative Thermogravimetric Analysis (DTG), while kinetic parameters were calculated using the Coats–Redfern approach. The evaluation covered mass degradation profiles and combustion parameters—specifically ignition temperature (Ti), peak temperature (Tp), burnout temperature (Tb), DTGmax, ignition index (Di), combustion index (S)—as well as activation energy. The results indicate that a blend of 20% hydrochar and 80% coal yielded the best combustion performance, evidenced by the lowest Ti (257.20°C), highest DTGmax (7.984), and lowest final residue (3.85%). Furthermore, hydrochar activated with 0.5 M NaOH exhibited the highest combustion index (S) of 6.769 and lower activation energy compared to pure coal, indicating superior thermal reactivity. These findings demonstrate that NaOH activation enhances hydrochar quality, offering significant potential for its use as a biomass fuel in coal-fired power plant co-firing applications.