Whether originating from anaerobic digester or landfills, methane (CH4) is the end-product of value and must be as pure as possible.

Separating methane from the other (undesirable) gases is a required optimization of the process. The two main undesirable gases are carbon dioxide (CO2) and hydrogen sulfide (H2S), both of which are removed by separate scrubbing units.

To ensure maximum purity of the end product of value (CH4), it is imperative to monitor the yield efficiency of the scrubbers. This is particularly true of H2S removal; as a matter of fact, presence of H2S in the methane at concentrations higher than a few parts-per-million can have dire economic consequences, forcing early overhaul of the internal combustion engines driving the generator, and speeding up degradation of methane containment and transport vessels.

Optimization of the methanization process and reduction of chemical stress on infrastructure requires the simultaneous rapid measurement of all three compounds (CH4, CO2, and H2S) with high sensitivity and without cross response. Of course, the sensing method utilized must be as reliable and as low maintenance as possible.

The Proceas Biogas, based on the patented OFCEAS (Optical Feedback Cavity Enhanced Absorption Spectroscopy) technology coupled to the patented low pressure sampling technology enables the measurement of these greenhouse (CO2, CH4) and potentially corrosive (H2S, H2O, O2) gases.

Measurement of these compounds (CH4, CO2, H2S and H2O; O2 as an option):

- is reliable;

- is very low maintenance;

- is insensitive to cross response phenomena (despite the very wide scale of concentrations measured, from ppm's for H2S to 10's of % for CH4 and CO2);

- has very low levels of detection;

- has response times measured in seconds;

- has a wide dynamic concentration range (e.g. H2S 0.5% at the beginning of the process to less than 10 ppm at the end of the process);

- does not experience instrumental response drift (self-standardization);

- does not require regularly schedule re-calibration (self-calibrating direct measurement);

- does not require sample conditioning;

- is a laser spectrometer capable of multi-components analysis;

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