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EAI presents Cleantech Snapshots: a quick summary of some of the most interesting and innovative areas in clean technology that will drive the sustainability movement in future.


This snapshot focuses on Energy from Landfill gas. Within this page you will find


Overview

  • Landfill gas production results from chemical reactions and microbes acting upon the waste at landfills, usually municipal solid waste. As solid waste in landfills decomposes, landfill gas is released
  • Landfill gas consists of approximately 50% methane, 42% carbon dioxide, 7% nitrogen and 1% oxygen compounds
  • Earlier, landfill gas used to be flared. But many landfills today utilize the gas on site to either produce heat or electricity
  • As methane is a potent GHG (21 times as potent as CO2), one can expect many landfills worldwide to start converting the gas to power
  • Landfill gas is a readily available, local, and renewable energy source that offsets the need for non-renewable resources such as oil, coal and gas

Landfill gas energy cycle

Landfill gas energy cycle(Image source)

Production

  • Landfill gases are produced during the natural process of bacterial decomposition of organic material contained in solid waste landfills
  • A number of factors influence the quantity of gas that a solid waste landfill generates and the components of that gas
    • The factors include the types and age of the waste buried in the landfill, the quantity and types of organic compounds in the waste, and the moisture content and temperature of the waste. Temperature and moisture levels are influenced by the surrounding climate

Utilization

  • The gases produced within a landfill can either be collected or flared. If collected, the gas has several different pathways it can take
  • The landfill gas can be utilized directly on site by a boiler or any type of combustion system. This provides raw heat for processes
  • Electricity can also be generated on-site through the use of micro turbines, steam turbines, or fuel cells
  • The landfill gas can also be sold off-site and sent into natural gas pipelines. This requires the gas to be processed into pipeline quality by removing the water, carbon dioxide, nitrogen, hydrogen, oxygen, and any other trace contaminants
  • Landfill gas can also be used to evaporate leachate, another byproduct of the landfill process

Composition

  • Land Fill Gas is about 50% methane and 50% carbon dioxide and water vapor. It also contains small amounts of nitrogen, oxygen, and hydrogen; less than 1 percent is non-methane organic compounds (NMOCs); and trace amounts of inorganic compounds
  • Some of these compounds have strong, pungent odor. NMOCs consist of certain hazardous air pollutants (HAPs) and volatile organic compounds (VOCs), which can react with sunlight to form ground–level ozone (smog) if uncontrolled

Advantages

  • Reduce emission of GHGs
  • Generate additional revenue
  • Increase economic benefits through job creation and market development
  • Demonstrate environmental leadership
  • Reduce environmental compliance costs
  • Improve air quality
  • Conserve land