GM Green Methane

Financed by: GM Green Methane Period: 2017

Introduction

Monitoring of a biogas to biomethane upgrading prototype The activities to be implemented are as follows:

• Inspection and sampling of raw biogas, purified biogas, biomethane and offgas;
• Quantification of biomethane, carbon dioxide, hydrogen, carbon monoxide, oxygen and nitrogen in samples by gas chromatography with heat conductivity detection (TCD); determination of calorific value, density, Wobbe index and methane number;
• Quantification of methane, carbon dioxide, hydrogen, carbon monoxide, oxygen and nitrogen;
• quantification of organic compounds containing chlorine, fluorine, sulfur (mercaptans) and nitrogen (amines); identification and speciation of volatile organic compounds by gas chromatography and mass spectrometry (GC / MS);
• Quantification of hydrogen sulphide and total sulfur;
• Quantification of total chlorine, total fluorine and ammonia by ion chromatography

Aims

The activity aims to evaluate the performance of a biomethane upgrading prototype based on potassium carbonate. The purpose of the monitoring is therefore to assess the quality of the biomethane produced for subsequent use for injection into the network and as a fuel for transport. Another objective is the verification of the efficiency and environmental sustainability of the process, through the verification of methane losses in the offgas emission.

Description

The prototype is located in Este (PD), and is currently fueled with biogas from the organic fraction of municipal solid waste. The prototype consists of a purification unit (removal of sulfur compounds and organic compounds) and an upgrading unit (removal of carbon dioxide and dehydration). Prior to the activities, an inspection of the plant is foreseen to define in detail the sampling methods and sampling points. There are 4 pick-up points:

• 1 - Raw biogas: biogas produced by the anaerobic digestion plant, upstream of any type of pre-treatment;
• 2 - Purified biogas: this point is located immediately upstream of the injection into the upgrading unit, or downstream of the desulphurization and abatement units of volatile organic compounds;
• 3 - Biomethane: final product of the prototype downstream of the upgrading unit, for which compliance with the requirements for the final use is to be verified;
• 4 - Offgas: by-product of the upgrading unit, mainly containing carbon dioxide.

  The data obtained during the monitoring campaign will be compared and integrated with the previous measurements made by GM, in order to obtain information on the temporal stability of the technology. The data will also have to be integrated with current knowledge on carbon dioxide abatement technology on potassium carbonate solutions. Finally, the data will be integrated with the electrical and thermal consumption of the prototype, in order to evaluate the economic and environmental sustainability of the process.