Having a quantitative indication of the biogas production of a landfill is crucial for all life stages of the landfill itself up to 30 years after its final closure.
If the biogas produced in waste storage does not follow the route of the systems designed for collecting and conveying it, it will find preferential migration routes until it is dispersed into the atmosphere in the form of fugitive emissions or, even before it escapes into the atmosphere, it may cause overpressure phenomena inside the waste collection body with further problems in terms of environmental and safety-related risks and impacts.
Furthermore, as the collected biogas is characterized by the methane macro-component, it is considered a flammable gas and if sent for energy recovery treatment (in engines, turbines, oxidizers etc.) it may guarantee economic revenues.
If we consider that it is really difficult to consider waste, as well as the storage of waste in landfills, in the same way as a ‘raw material’ with known, constant characteristics, that the waste degradation and fermentation environment (the landfill) takes on different connotations depending on numerous parameters that are not always known and in any case are not very easy to control, and that the simulations of the phenomenon of biogasification of waste conducted in the laboratory have obtained interesting but often not homogeneous results, it is understandable why, over the years, the need has arisen to have models for forecasting landfill biogas productivity.
Technical literature provides various models classified according to main types (Damiani and Gandolla, 1992), distinguishing empirical models, stoichiometric models, biochemical models, ecological models etc.
From direct experience, we believe the model developed by the Italian expert Enrico Magnano during his thirty years working in hundreds of landfills around the world, called the BIO-7 model, which has now evolved into BIO-8, is very valid.
Ultimately, having reliable data on biogas (LFG) productivity over time enables the operator to make the best technical choices in terms of design, construction, management and post-management for the landfill itself, addressing the dual environmental effect of biogas:
if collected and exploited, it can be a potential alternative energy source thanks to its high methane content; on the other hand, it can have a significant environmental impact when released into the atmosphere, since methane is the second most important greenhouse gas after carbon dioxide, with a GWP 28 times higher than that of CO2
