Jenbacher Landfill Gas Engine
Jenbacher landfill gas engines use the gas — including methane, carbon dioxide, and nitrogen — created during the decomposition of organic substances in a landfill. With a calorific value of approximately 5 kWh/Nm³, landfill gas constitutes a high-value fuel for gas engines that can be effectively used for energy generation.
Environmental Benefit
One GE Jenbacher J420 gas engine running on landfill gas is designed to generate electricity while avoiding the emission of more than 40,000 metric tons of CO2-equivalent per year through methane destruction and displaced grid electricity production; this is equivalent to the annual CO2 emissions of over 7,800 passenger cars on U.S. roads.
Operating Benefit
The global installed base of over 1,250 GE Jenbacher gas engines running on landfill gas is designed to generate more than 9.4 million MWh of electricity per year, which would require more than 2.5 billion cubic meters of natural gas for generation in average US natural gas-fired power plants.
Landfill gas as an energy source
Landfill gas is created during the decomposition of organic substances and consists of methane (CH4), carbon dioxide (CO2) and nitrogen (N2). Uncontrolled venting of landfill gas hampers or prevents rapid, scheduled recultivation of a landfill site. To prevent this and to avoid offensive smells, smouldering fires or the migration of gas, the gas must be continuously extracted under controlled conditions. With a calorific value of approximately 5 kWh/Nm³, landfill gas constitutes a high-value fuel for gas engines that can be effectively used for energy generation.
Creation of landfill gas
Household waste contains approximately 150 to 250 kg of organic carbon per ton. These substances are biologically degradable and are converted by microorganisms into landfill gas in the absence of air. Stable, anaerobic methane fermentation begins one to two years after the waste is deposited in the landfill.
If the landfill gas is collected constantly and in a controlled fashion, the following average values are achieved after the gas collection process has been properly adjusted:
- Methane (CH4): approximately 40–50 percent by volume
- Carbon dioxide (CO2): approximately 35–45 percent by volume
- Nitrogen from air (N2): approximately 5–15 percent by volume
- Oxygen from air (O2): approximately 1–3 percent by volume
- Water vapour (H2O): saturated
The Jenbacher concept
Perforated tubes are drilled into the landfill body and interconnected by a pipe work system. Utilizing a blower, the gas is sucked from the landfill, compressed, dried and fed into the gas engine. For safety reasons, the installation of a gas flare is recommended so that excess gas can be burned off in the event of excessive gas production. In most cases all the electrical power generated is fed into the public grid.
Volume and production process figures
Gas formation is influenced by a number of factors such as the landfill material, the storage height and density of the landfill material, water content, air temperature, atmospheric pressure and precipitation levels. The decomposition process in a landfill providing gas with sufficient methane content lasts approximately 15 to 25 years, with the gas volume decreasing continuously over the years.
One ton of household waste produces approximately 150 to 200 Nm³ of landfill gas with a methane content of approximately 50 percent to 60 percent in a time period of 15 to 25 years. An average household waste landfill with a utilized storage capacity of 500,000 tons can be expected to generate about 8.5 million Nm³ of landfill gas per year, corresponding roughly to an energy content of 42 GWh. From this volume of gas, approximately 16 GWh of electricity or 20 GWh of heat can be generated per year — that corresponds roughly to the demand of 6,500 households.
Advantages
- Problem waste gas is converted to an energy source
- Methane (CH4) releases into the atmosphere are reduced or eliminated
The climate-relevant effect
- Global Warming Potential (GWP) of methane is 21 times higher than that of CO2
- Landfill gas presents an alternative to conventional fuels
- Highly efficient for power generation with gas engines
Our competence
We have the ideal solution for efficiently utilizing landfill gas. With more than 25 years of experience in the combustion of landfill gas and currently more than 950 landfill gas systems with a total electrical output of more than 900 MW installed throughout the world, the Jenbacher product team offers an unparalleled breadth of expertise, references and solution variants.
