Indonesia is the largest palm oil-producing country in the world, with a share of 59%. In 2013 to 2023, palm oil production in Indonesia increased by an average of 4.7%. The emergence of waste also increases along with the increase in production. Palm oil mill waste consists of palm oil mill liquid waste (POME), mesocarp fiber, palm kernel shells, and empty oil palm bunches. In this study, waste from palm oil, such as mesocarp fiber and empty fruit bunches, can be used to replace the palm kernel shells. Moreover, the addition of biogas to mesocarp fiber and empty fruit bunches will be used as an addition to replace fuel in boiler. Gas emission (SO2, NO2 and CO2) is key parameter for process combustion in boiler Boiler gas emission is regulated by Ministry of Environment regulation. Aim: This study was aimed to analyze and determine the optimum composition that can be used in boiler fuel where gas emissions are the main parameters, especially N02, SO2 & CO2. Methodology and results: The method in this study are a literature review, analyzing materials for proximate and ultimate, then analyzing the results. The results of this study are the optimum composition of 85% mesocarp fiber, 10% biogas, and 5% empty bunch fiber where composition SO2 and NO2 do not exceed the threshold and the lowest CO2 gas production. Conclusion, significance and impact study: This study can be impacted to decrease waste from palm oil industry and used the waste palm as new alternative energy that can replace fuel in boiler.