page_title: Landfill gas utilization
section_title: Pipeline-quality gas, CNG, LNG
hierarchical_section_title: Landfill gas utilization / Use of landfill gas / Direct use / Pipeline-quality gas, CNG, LNG
caption_attribution_description: English: Gas separator membrane skid used in pressure swing adsorption to separate carbon dioxide from landfill gas to create utility-grade high purity methane gas to supply as natural gas
context_page_description: Landfill gas utilization is a process of gathering, processing, and treating the methane or another gas emitted from decomposing garbage to produce electricity, heat, fuels, and various chemical compounds. After fossil fuel and agriculture, landfill gas is the third largest human generated source of methane. Compared to CO
  2, methane is 25 times more effective as a greenhouse gas. It is important not only to control its emission but, where conditions allow, use it to generate energy, thus offsetting the contribution of two major sources of greenhouse gases towards climate change. The number of landfill gas projects, which convert the gas into power, went from 399 in 2005 to 519 in 2009 in the United States, according to the US Environmental Protection Agency. These projects are popular because they control energy costs and reduce greenhouse gas emissions. These projects collect the methane gas and treat it, so it can be used for electricity or upgraded to pipeline-grade gas. These projects power homes, buildings, and vehicles.
context_section_description: Landfill gas can be converted to high-Btu gas by reducing its carbon dioxide, nitrogen, and oxygen content. The high-Btu gas can be piped into existing natural gas pipelines or in the form of CNG (compressed natural gas) or LNG (liquid natural gas). CNG and LNG can be used on site to power hauling trucks or equipment or sold commercially. Three commonly used methods to extract the carbon dioxide from the gas are membrane separation, molecular sieve, and amine scrubbing. Oxygen and nitrogen are controlled by the proper design and operation of the landfill since the primary cause for oxygen or nitrogen in the gas is intrusion from outside into the landfill because of a difference in pressure. The high-Btu processing equipment can be expected to cost $2,600 to $4,300 per standard cubic foot per minute (scfm) of landfill gas. Annual costs range from $875,000 to $3.5 million to operate, maintain and provide electricity to. Costs depend on quality of the end product gas as well as the size of the project. The first landfill gas to LNG facility in the United States was the Frank R. Bowerman Landfill in Orange County, California. The same process is used for the conversion to CNG, but on a smaller scale. The CNG project at Puente Hills Landfill in Los Angeles has realized $1.40 per gallon of gasoline equivalent with the flow rate of 250 scfm. Cost per gallon equivalent reduces as the flow rate of gas increases. LNG can be produced through the liquidfication of CNG. However, the oxygen content needs to be reduced to be under 0.5% to avoid explosion concerns, the carbon dioxide content must be as close to zero as possible to avoid freezing problems encountered in the production, and nitrogen must be reduced enough to achieve at least 96% methane. A $20 million facility is estimated to achieve $0.65/gallon for a plant producing 15,000 gallons/day of LNG (3,000 scfm). Estimates are in 2007 dollars.
caption: Gas separator membrane skid used in membrane separation process to extract carbon dioxide[15]
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