Heating value enhancement by biogas purification using natural zeolite and rice straw-based biochar

Abstract

Biogas has many incentives to replace firewood and crop straw for cooking in rural area. However, to access sustained adoption of clean, carbon neutral and eco-friendly household fuels, raw biogas needs to be purified before used. Beside methane (CH4), raw biogas contains trace components adversely affecting appliances or end-user. For example, carbon dioxide (CO2), the greatest impurities in biogas, affect the decrease of heating value. In some literature, the adsorption for CO2 was claimed to be cheap, simple and adoptable for CO2 removal. Carbon dioxide removal using rice straw-based biochar combined with natural zeolite (Z-RB) at room temperature and gas pressure range of 5-7 bar. Carbon dioxide removal using Z-RB increased the theoretical and empirical heating value of biogas from 1214.48 to 1766.34 kJ and from 276 to 288.55 kJ respectively. From this observation, the blue flame that appeared from the combustion of purified biogas using Z-RB went out for longer than using natural zeolite only (Z-Z).