Replacing Agricultural Diesel Fuel with Biomethane from Agricultural Waste: Assessment of Biomass Availability and Potential Energy Supply in Piedmont (North-West Italy)

Agricultural and livestock wastes are an important resource for the production of renewable fuels such as biomethane, and the effective management of the components of supply chain, such as available biomass feedstock, are critical to the transition to a low-carbon circular economy. Considering that more than half of the emissions (CO2eq) generated in agriculture come from the use of fossil fuels to power tractors and other agricultural machinery, replacing diesel fuel in tractors with biofuels produced within the agricultural supply chain could contribute to greenhouse gas emissions reduction and to energy self-sufficiency for the local agricultural sectors. This study evaluated, at the regional level (Piedmont—north-west Italy), the potential production of biomethane from local agricultural wastes (crop residues and livestock manure), the potential energy supply to power tractors and the potential CO2 emission reduction by replacing diesel fuel. Based on mean annual available agricultural wastes over the last seven years (2015–2021) in the Piedmont region, the annual potential biomethane yield of 910 × 106 m3 year−1 was estimated, equivalent to a thermal energy of 30.1 × 109 MJ year−1, which is 3.8 times higher than the energy requirements for the regional tractors’ fleet. The estimated potential CO2 emission reduction is about 93.8 t of CO2 year−1, corresponding to 16.8% potential reduction. The study demonstrates the potential of local agriculture to replace diesel fuel with biomethane from waste to meet energy needs and carbon neutrality.