Landfill Gas Info

The landfill gas, which develops during biochemical decomposition processes and is emitted through the cover layer or directly from the landfill (due to high gas pressures), may under certain conditions pose a great risk for humans and animals alike.

The operators would have to anticipate the toxicologically alarming emissions (toxicity and local reduction of oxygen contained in both the atmosphere and soil) and the danger of combustions and explosions. Additionally, methane gases contribute to the greenhouse effect and destroy the ozone layer (at a factor 21 times higher than CO2).

A minimization of emissions can be achieved by installing active degassing facilities in combination with suitable cover layer sealing systems. The volumes produced by the active degassing plants are worth utilizing. The U.S. in the early 1970s saw the first active landfill degassing system by using a flare.

The high heating value of the landfill gas up to 6 kWh/Nm³ (about 4.5 to 5 kWh/Nm³) make this utilization a worthwhile investment. The generation of electric power, with its efficiency of 33 % and the provision of gas to the gas distribution system (at the user point) appears most suitable. Moreover, heat extractions from landfills are also an option. The generation of electric energy may also be done by using turbines, which calls for an additional heat extraction.

In principle, gas volumes are not tangible and can therefore not be exactly calculated. However, field analyses / measurements, which take into account the location characteristics of the landfill site and the state of fermentation, are suitable for bringing some light into an otherwise incalculable gas volume flow. A large share of methane contained in the soil air is not always a reliable indicator for a stable and economically sustainable landfill plant.

DETES maintains plants operated with 5,000 Nm³/h. Generally, depending of their life cycle, mid-sized landfills reach gas volumes in the amount of 250 – 1000 Nm³/h only.

For the use of landfill gas and based on an energy content of 5 kWh/Nm³ and a exhaust rate of 500 Nm³/h (availability 85%) each year generates 18,000 MW thermal or, in electrical terms, about 6000 MW. A sound operation and a regular maintenance of the machinery allow not only for an environmentally friendly effect, but also contribute to a positive economic outlook.

Trace substances, such as chloride, fluoride, sulfur, and silicon may be harmful for the active degassing process and even damage the materials used for the machinery. In extreme cases, the industry provides specially designed devices for the prior purification of gasses.

Vertical gas collectors (gas wells) have proven to be a good choice when it comes to gas capping. After the measuring of the local determination of the gas cap site, and depending on the overall expansion and the waste compression, the usual intake radius for gas wells is 30 to 50 meters.

Our website provides you with information pertaining to the measuring systems used for certain types of projects.