Monitoring biogas surface emissions

The monitoring of biogas surface emissions is one of the most vital areas of management and supervision of a landfill, be it during production or after closure.

Landfill biogas is the result of the fermentation of the decomposing organic elements of waste in a landfill. This process generates overpressure. Once the alveolar spaces are saturated, the gas naturally tends to escape so that surface biogas emissions usually correspond to the specific biogas production of the wastefill.

To counteract the unchecked migration of biogas into the atmosphere or adjacent soils, a system of extraction is usually put into place which serves to harness the biogas before it can reach the outer limits of the wastefill. The gas so harnessed is destined either to be flared or to be fed into a transformation plant to produce electricity.

The extent of transformation by the flare or electrical generators enables the transformation of surface emissions into controlled emissions of reduced environmental impact in that they are oxidated.

Consequently, the overall production of biogas corresponds to the sum of captured emissions, surface emissions, any lateral migration flows and, finally, cortical oxidation.

When assessing captured emissions, we must bear in mind that biogas is generally composed of methane and carbon dioxide. Biogas plants, be they thermo destruction (flare) or energy transformation (endothermic engines), are based on the oxidation of methane through combustion and the consequent transformation of methane into carbon dioxide and steam.

Emendo’s aim in this phase of analysis is therefore to assess and identify the “residual” surface emissions resulting from the difference between the total biogas exhalation and the quantity harnessed and treated in a working plant.

It is imperative to assess surface emissions so as to enhance the captation process thereby reducing environmental impact and the considerable hazards inherent in these emissions.

Assessment of diffuse emissions should enable us to:

  • Quantify gas emissions;

  • Establish and assess the location of these emissions.

Emendo’s service comprises an analytical assessment of emission flows according to precise regulations laid down by UK Environmental Agency directives. The analyses are carried out using a flux-box and a Flame Ionisation Detector (FID) capable of registering minimal concentrations of biogas (ppmv).

Precise computing and data analysis procedures allow us to arrive at exact results regarding the flow and quantity of biogas emissions

Surface biogas emissions analyses can be aided by a preliminary thermographic survey which allows us to locate areas where there are thermal incongruities on the surface of the waste landfill that require more specific detailed analyses.