What is landfill gas and how is it collected?

Landfill gas (LFG) is produced by anaerobic decomposition of organic waste in landfills. Composition includes methane (45-60%), carbon dioxide (40-60%), and trace gases (nitrogen, oxygen, hydrogen sulfide, volatile organics). Production peaks 5-7 years after waste placement and continues for decades. Collection systems include: vertical extraction wells (pipes drilled into waste mass), horizontal collectors (perforated pipes installed as waste is placed), and header pipes connecting to blower/flare station. Gas is typically flared (destroyed) or used for energy (electricity generation, direct thermal use, or upgraded to pipeline-quality biomethane). Collection efficiency is 60-85%. Benefits include greenhouse gas reduction (methane is 25x more potent than CO2), odor control, explosion prevention, and renewable energy generation. EPA requires collection at large landfills under NSPS and EG regulations.