Author(s)

BENEDICTA CROCE, SANDRO ROSSI, MOSÈ ROSSI

Abstract

The increasing demand for low-carbon energy carriers is increasingly driven by the urgent need to address climate change and reduce the environmental impact of conventional energy systems. In this context, biogas and biomethane are emerging as key renewable solutions within the global energy transition. This study investigates a biogas plant located in northern Italy equipped with an Ingenia-patented system designed to reduce ammoniacal nitrogen and CO₂, thereby improving biogas quality and enabling its upgrade to biomethane. A comparative energy and environmental analyses are carried out to evaluate the use of either biogas or biomethane as fuels in combined heat and power units having an electrical and thermal power output of 410 kW and 400 kW, respectively, focusing on primary energy requirements and greenhouse gas emissions comparison. Results show that biomethane, due to its higher lower heating value, requires less fuel consumption than biogas to produce the same useful energy output (both electrical and thermal), thereby improving overall system efficiency. Specifically, the lower primary energy demand of biomethane leads to annual savings of up to 1.35 GWh. Moreover, if biomethane production matches the volume of biogas needed to deliver the same useful energy, the excess biomethane, approximately 142,400 Sm³, can be injected into the gas grid, contributing to enhanced national energy self-sufficiency. From an environmental perspective, results show that biogas use achieves an annual emissions reduction of approximately 880 tCO₂ equivalent, while biomethane slightly improves the performance, reaching about 900 tCO₂ equivalent avoided per year. Overall, the study demonstrates that biomethane offers enhanced energy efficiency and climate benefits, confirming its role as a valuable option for integrated low-carbon energy systems.

Keywords

biogas, biomethane, combined heat and power, CO₂ emissions reduction, energy systems, renewable energy