Landfill gas - origin and composition
Landfill gas arises from the decomposition processes of organic compounds and materials in waste. A distinction is made between aerobic and anaerobic processes. The composition of the gases depends very much on the age of the landfill, the type of materials deposited and the landfill. The first two months after filling up, the gas contains higher levels of nitrogen and oxygen from the supplied air and there is hardly any carbon dioxide or methane. Immediately after the landfill is sealed, the carbon dioxide content increases dramatically, while methane takes a few more months and is only formed when the anaerobic phase begins. Landfill gas remains stable over 20 years and is composed as follows:
- 50 vol% methane
- 40 vol .-% carbon dioxide
- 0-4% by volume nitrogen
- 5-7 vol% water
- 20 ppm hydrogen sulfide
- 30 ppm Merkaptene
In addition, there are many organic, sometimes toxic, traces.
Landfill gas hazards
In the 1940s to 1980s, almost every hole in Germany, like former gravel pits, was simply filled with waste. Household waste, building rubble, packaging and excavated earth ended in so-called old landfills, without words like basic or surface sealing ever being spoken. The results from the indiscriminately collected waste were dangers to nature and the environment from the release of pollutants and from the formation of explosive landfill gas. With the introduction of more and more advanced technologies and thanks to the state landfill self-monitoring regulation, many of these old landfills have been renovated, but even modern plants offer sufficient potential hazards from landfill gas:
Risk of fire and explosion
Methane as the main constituent of landfill gas forms a very ignitable mixture with atmospheric oxygen. Open light, smoking and fire must be avoided in rooms that are not adequately protected.
Carbon dioxide (CO2) in a concentration > 9 vol .-% causes suffocation in a few minutes. Especially in deeper pits and shafts into which landfill gas can flow, there is an increased risk of suffocation due to the lack of oxygen there.
Effects on the climate
Methane (CH4) is the second highest cause of the greenhouse effect after carbon dioxide (CO2). Together with animal husbandry and energy production, landfills are among the largest man-made sources of methane.
Processing and use of landfill gas
The Federal Environment Agency estimated that ten years after the end of the deposition of organic matter in landfills, there are still over 500,000 tons of methane to be treated each year. Landfill gas can be used as fuel in boiler furnaces or to generate electricity with gas engines. It is also possible to feed the gas supply network after the gas has been cleaned and compressed.
- Power range of 150 - 6000 Nm3/h
- Fully automatic control
- Data recording and transmission
- Low-maintenance design
- Weak gas utilization
- Regulatory criteria as specified
- Remote maintenance
- Designed as CDM/JI-Projects
- Integrated gas flare
- Integrated control of the CUP
- Gas cooling and conditioning
- Activated carbon filter for CUP
- Service contract specificaly to customer wish
Gastechnik Himmel – we offer solutions
You are planning a fully automatic landfill gas plant?
We support you from the project stage to the commissioning; we create technical documents ready for submission and consult you on all questions of implementation.
Based on the cold startup procedure performed in our factory - on request with TÜV inspection and certification - the commissioning shortens on site to approximately 2 days.
We specialize in the planning and production of plants in the field of environmental technology and thus want to make an important contribution to accelerating the energy transition. Take advantage of our decades of experience in gas technology and benefit from our know-how.