Heat Quality Enhancement and Carbon Dioxide Emissions Reduction from Coal Burning by Combining Low-Ranked Coal with Biomass Waste as A Clean Energy Solution to Achieve Energy Security in Indonesia
Indonesia is the fifth largest coal producer in the world with coal reserves reaching 39.56 billion tonnes. Coal reserves of medium and high quality are expected to be exhausted in 2048, therefore it is necessary to utilize low-ranked coals. Low-ranked coals have a low heating value (<5,100 kcal/kg) and produce greater CO2 emissions compared to medium and high rank coals. One method to increase heating value and reduce CO2 emissions from low-ranked coals is through the Utilization of hybrid coal. Hybrid coal is low quality coal combined with biomass waste and has undergone a pyrolysis process together. The mixing and co-pyrolysis of low-ranked coal with biomass waste such as rice husk, empty palm fruit bunches, and rubber wood with a ratio of 7:3 is known to be able to increase the final product calorific value by 31.10–44.12% and reduce non-neutral CO2 emissions by 15.56–21.31%. The hybrid coal production process is highly prospective to be implemented in Indonesia, especially in Central Java, South Sumatra and South Kalimantan. The payback period from the hybrid coal industry with a production capacity range of 540 thousand to 4.5 million TPY can be achieved in 10–13 years with a net profit range of IDR 137 billion to IDR 493 billion per year and a net present value range of IDR 285 billion to IDR 1.1 trillion.