The surface of a landfill can look still while the material underneath continues to change. Microorganisms break down organic matter. Where oxygen is absent, those processes can generate a gas mixture containing methane and carbon dioxide.
Gas moves through a changing waste body. Some can escape through the cover or other pathways. A collection system uses wells or horizontal collectors connected to pipes, with controlled extraction directing the mixture towards treatment.
Collection is one stage
Operators need to manage the system as conditions change. Drawing too little can leave gas uncollected. Drawing too aggressively can bring in air and create operating problems. Moisture, settlement and the age of the waste also affect performance.
Collected gas may be combusted in a flare or used in suitable energy equipment. Where methane is destroyed effectively, it is mostly converted to CO₂ and water. Some gas may remain unburned, so destruction performance needs evidence.
A whole-site view
Capture efficiency and destruction efficiency describe different things. The first concerns how much generated gas reaches collection. The second concerns how much methane entering treatment is destroyed. Quoting only the better-looking figure can mislead a reader about overall performance.
A credible assessment also examines the reference situation, regulation, project emissions and measurement uncertainty. Equipment photographs are useful context, but the calculation needs operating records.
Preventing food waste and keeping organics out of landfills remain important. Addressing gas from existing waste does not eliminate the reasons to improve how future material is managed. Both decisions belong in the conversation.
This is an explanation of established landfill-gas practice, informed by the US EPA handbook. It is not a description of a contracted ClimateCurrent installation or a promise about a future site.