Evaluation of greenhouse gas emissions, with a focus on methane emissions, from a municipal solid waste landfill and from a biogas power plant. The instrument used have been a tunable diode laser absorption spectroscopy (TDLAS) and a Fourier-transform infrared spectroscopy (FTIR). For the biogas plant, the evaluation of the annual flux of methane emission has been calculated through a Gaussian plume model. Results highlight the emissions hotspot in both the sites and show that methane concentrations return to values comparable to environmental values even at short distances (50-100 m) from the main sources.