Methane Slip: The Number the RNG Industry Buries

The RNG industry reports capture rates of 85-95%. These numbers are real. They are also misleading. What they do not include is methane slip: the methane lost during processing, compression, transport, and injection into the pipeline system.

What Methane Slip Actually Is

Methane slip occurs at every stage of the RNG value chain. Raw biogas upgrading systems vent methane during the separation of CO2 and other impurities. Compression stations leak at seals, valves, and connections. Pipeline transport introduces fugitive emissions along every mile of infrastructure.

Independent measurements consistently show total system losses of 5-15%, depending on technology, maintenance, and pipeline distance. Some studies have documented slip rates above 20% at poorly maintained facilities.

This is not a rounding error. Methane has 80x the warming potential of CO2 over 20 years. A system that captures 90% of methane but loses 10% through slip has not solved the problem. It has relocated it.

The Comparison

An enclosed flare destroys methane on-site. There is no processing step. There is no compression. There is no transport. There is no pipeline injection. The destruction efficiency is 98%+ by design, verified by continuous monitoring.

The comparison is not close:

RNG system: 85-95% capture, minus 5-15% slip = 72-90% net destruction Enclosed flare: 98%+ destruction, zero transport losses = 98%+ net destruction

When you factor in methane's warming potential, the gap between 80% and 98% net destruction is enormous. It is the difference between a meaningful climate intervention and an incremental improvement wrapped in a compelling financial narrative.