The composition, the combustion-related characteristic data and the accompanying substances in the "processed biogas" — summarized under the term "gas properties" — are crucial for injection. In particular, these are the data described in the DVGW work sheet G 260 "gas properties", G 262 "use of regeneratively produced gases" and in the DVGW Worksheet G 685 "gas billing" and G 486 and are defined within their respective limits. Table 7 shows the principal conditioning parameters for injecting into a grid.

The methane content in biogas is not subject to any defined restriction. However methane is, according to the latest technical data, the major combustible component and thus largely determines the calorific value and hence the Wobbe index, as long as no liquid gas admixture is included. According to worksheet DVGW-G 262, the maximum permissible CO2 content is 6 Vol.-%. Since biogas consists mostly of methane and carbon dioxide, processing to at least a minimum methane content of 94 vol -% is assumed. Together with the fractions of oxygen and nitrogen, the biogas has a maximum carbon dioxide content of 5,6 Vol.-%.

According G 260, the maximum permissible O2 volume fraction is 3% in dry networks, otherwise 0.5%. German natural gas grids are considered to be dry.

It is important to note that CO2 and O2 in combination with moisture can lead to corrosion in pipes, fittings and equipment.

In addition to the above conditions, of course the information on sulphur compounds and other impurities and accompanying substances given in G 260 is also to be noted. The data for the dew point temperatures lie below the requirements defined in G 260 (about 4 — 7 ° C (soil temperature at 1 m depth) at line pressure).