Gas Collection

We offer both passive and active gas collection systems.

Passive systems use gas collected in vertical and horizontal wells with a variety of pressures and gas concentrations present.

Active systems that are well designed are generally the most effective way of collecting gas from vertical and horizontal gas wells. Vertical wells are generally 10-25 metres deep, depending upon the landfill depth and the available equipment. They are usually spaced at 15-50 metre intervals. Horizontal wells consist of an evacuated trench that is then backfilled with permeable gravel. Active gas collection systems include vacuums or pumps to move gas out of the landfill. They also include pipe work that connects the collection wells to the vacuum.

Through maintaining low pressure in the wells a preferred migration route for the gas is created that assists with its collection. All wells normally have valves to regulate gas flow and to provide a sampling port, to assess gas generation, composition and pressure.

Gas utilisation

Landfill gas is treated through combustion, which destroys the methane by splitting it into water vapour and carbon-dioxide. Methane is 21 times more harmful as a greenhouse gas than carbon-dioxide. It is important that the combustion process does not lead to any additional or harmful emissions and that it complies with the respective environmental legislation. In Germany, for example, strict legislation is applied through the "TA-Luft" (Emission Control Act). Elsewhere, projects based on the Kyoto-mechanisms explicitly demand the transfer of technology to the project country. This includes emission control systems because in many countries such control systems and the associated emission limits do not exist.

Green Gas offers two combustion options: Flaring and gas powered engines.

Gas-to-energy (G.A.S. technology)

With more than 200 plants built, representing an installed power of more than 150MW_el, Green Gas has the expertise to transform unwanted landfill gas into clean energy.

Our integrated solutions cover the entire system from gas collection equipment, flares and compressors to gas treatment and co-generation units. We provide the necessary control systems, transformers and grid connection to make the whole process work. Our flexible technology is also ideally suited to variations in gas quantities and qualities. With a modular design, proven technology and excellent 24/7 service, Green Gas plants have high operational availabilities.