Renewable Natural Gas and
the Importance of Hydrogen Sulfide Process Monitoring

Renewable natural gas (RNG) is a pipeline quality gas that is interchangeable with conventional natural gas. Historically methane produced from locations such as landfills, livestock operations, or wastewater treatment plants was lost to the atmosphere. However, as regulators update emission rules and implement renewable fuel standards, RNG has become a rapidly growing segment of next generation renewable fuels. In fact, a study published by the National Association of Clean Water Agencies suggests that potentially 12% of electrical production in the United States could be generated from RNG sourced from wastewater treatment plants.

However, before gas generated from renewable sources is released to pipelines, it first must be upgraded to meet the pipeline specifications. This typically involves removing components such as CO₂, H₂O, and H₂S. Hydrogen sulfide is a particularly challenging component for operators to remove. It is a toxic and corrosive gas, but common processes like amine or selexol units are not economical given the scale for most RNG facilities. Instead, operators rely on packed columns which selectively remove H₂S using sorbents. While these systems can reduce H₂S levels from several thousand parts per million down to approximately four parts per million, they need to be periodically changed as the sorbents become saturated.

Operators rely on process analyzers to detect hydrogen sulfide breakthroughs and swap to a new column. However, most analyzers on the market either lack the sensitivity to detect the hydrogen sulfide at the levels and pressures leaving the packed columns or require costly carrier gases that must be continuously replaced for the analyzer to keep functioning.

To resolve this issue Applied Analytics has developed our Zeta™ spectrometer used in conjunction with our OMA-300 process analyzer. When equipped with a Zeta™ spectrometer, the OMA-300 UV ZETA can measure low levels of H₂S found at these facilities without the need for expensive reagents that need replacing. As an added benefit this system uses a solid-state design which does not contain moving parts that can fail or would otherwise require replacement. You can click the link here to learn more about our analyzer and how it can help your operation.