Toward sustainable energy: Fuel properties and combustion behavior of torrefied king grass at various briquetting pressures

Abstract

Most countries are facing a steady decline in conventional energy resources, prompting governments to prioritize the development of renewable alternatives. With its rich biodiversity, an agricultural country like Indonesia holds significant potential for biomass utilization – one promising feedstock being king grass (Pennisetum purpureoides). This study examines the physical and thermal characteristics of torrefied king grass bio-briquettes produced under varying briquetting pressures (100, 200, 300, 400, and 500 kg/cm²). Proximate analysis reveals that torrefaction enhances fuel quality by increasing fixed carbon content while reducing moisture and volatile matter. The calorific value, density, and dimensional stability of the briquettes improve with higher briquetting pressure, whereas brittleness declines, resulting in more durable and manageable briquettes. Combustion tests indicate that increased pressure leads to slower burn rates and extended combustion duration. Water boiling tests further show that although high-pressure briquettes require more time to reach boiling point, they maintain more stable combustion efficiency. Overall, the results underscore the viability of torrefied king grass bio-briquettes as a sustainable and efficient alternative energy source to help address Indonesia’s growing energy demands.