Abstract
The growing demand for sustainable energy highlights the importance of biogas as a renewable and low-emission fuel. This study investigates the potential for biogas production from wastewater sludge via anaerobic digestion (AD) as a substitute for natural gas in power generation plants. A comparative analysis was conducted at the Al-Khums power plant located in Libya, focusing on efficiency and environmental impacts. The AD process was modeled through its four stages, namely: hydrolysis, acidogenesis, acetogenesis, and methanogenesis. The resulting upgraded biogas composition after purification was found to be 97.70% CH₄ and 2.30% CO₂. Process simulations using Aspen Plus v.12 evaluated the performance of biogas versus natural gas under varying loads. Key indicators, including thermal efficiency, specific fuel consumption, and CO2/NOx emissions, were compared. The electrical energy per cubic meter (m³) was evaluated for natural gas and biogas fuels, in terms of MWh generated for a typical wastewater treatment plant. The electrical energy generated per cubic meter (m³) from each fuel showed that biogas demonstrates significant environmental .advantages, supporting its role in the sustainable energy transition