Renewable Natural Gas Definition and How It's Produced

Renewable natural gas (RNG)—also called biomethane—is a low‑carbon fuel made by cleaning biogas from decomposing organic waste. Once upgraded, it’s pipeline‑quality methane that performs like conventional natural gas, so existing boilers, CHP units and CNG/LNG vehicles can use it without changes. Upgrading removes carbon dioxide, water vapour, hydrogen sulphide and other impurities, leaving a high‑methane gas for grid injection or onsite use. Because it uses existing infrastructure, projects can scale quickly.

This article defines RNG in plain terms and walks through how it’s made, where biogas comes from, the key upgrading steps and gas‑quality standards, and how RNG is delivered and used. We’ll also cover compatibility with fossil gas, climate impacts and leakage management, the policies shaping the market (including Canada), how to choose upgrading technology, project economics, and current adoption trends.

RNG, biomethane and biogas: what's the difference?

If you’re looking for a clear renewable natural gas definition, start with the source. Biogas is the raw product of decomposing organics; biomethane—also called renewable natural gas (RNG)—is that biogas upgraded to pipeline‑quality so it can replace fossil natural gas in the grid or at the point of use.

• Biogas: Raw mixture from landfills, anaerobic digesters, wastewater and organics; typically contains CO₂, H₂S, moisture and about 45–65% methane.

• Biomethane/RNG: Biogas that’s been cleaned to remove contaminants and concentrate methane; fully interchangeable with conventional natural gas.

• Typical use: Biogas often powers onsite heat/CHP after minor cleanup, while RNG suits pipeline injection, vehicle fuel (CNG/LNG) and industrial heat.

How renewable natural gas is produced from biogas

Producing RNG starts with biogas from landfills, digesters or wastewater. Raw biogas carries 45–65% methane plus carbon dioxide and water vapour. Upgrading—also called conditioning—removes moisture, CO2 and hydrogen sulphide, reduces oxygen and nitrogen, and strips siloxanes and VOCs. The outcome is biomethane with 90%+ methane; for grid injection, typical specifications are 96–98%, making renewable natural gas interchangeable with conventional natural gas.

• Pretreatment and upgrading: remove H2S, moisture and CO2 to reach pipeline-quality methane.

• Polishing and assurance: reduce O2/N2, remove siloxanes/VOCs, verify specs; then compress for injection or vehicle fuel (CNG/LNG).

Biogas sources: landfills, farms, wastewater and organic waste

RNG starts with biogas from four dependable waste streams: municipal solid waste landfills, livestock farms, wastewater treatment plants, and organic waste processors. Landfill gas (LFG) forms in situ; on farms and at WWTPs, anaerobic digesters convert manure and biosolids into biogas; food and commercial organics are digested or co‑digested. These steady feedstocks make projects bankable and scalable—and they anchor any practical renewable natural gas definition: biogas upgraded to pipeline‑quality biomethane.

• Landfills: LFG captured and upgraded; increasingly used for pipeline and vehicle fuel.

• Livestock farms: Manure-to-biogas via digesters; strong methane‑reduction potential.

• Wastewater plants: Digester gas from sludge; some facilities upgrade to RNG.

• Organic waste: Food manufacturing, supermarkets and municipalities supply digesters for RNG.

Upgrading steps and gas quality requirements

Turning biogas into pipeline‑quality biomethane is a controlled, staged process that strips contaminants and concentrates methane to meet grid or vehicle‑fuel specs. Per EPA guidance, treatment removes moisture, carbon dioxide and trace contaminants (e.g., hydrogen sulphide, siloxanes and VOCs), while reducing oxygen and nitrogen. The outcome is RNG with ≥90% methane; for pipeline injection, typical methane content is 96–98%, making it interchangeable with conventional natural gas. Leading systems go further, driving oxygen to very low ppm (e.g., <10 ppm) and tightly managing water to meet utility dew‑point limits—central to any rigorous renewable natural gas definition.

• Pretreatment: Desulphurisation and siloxane/VOC control protect downstream equipment.

• CO₂ removal: Membranes/solvents elevate methane concentration efficiently.

• Drying and polishing: Dehydration plus O₂/N₂ reduction and final contaminant cleanup.

• Compression and QA: Bring to pressure, verify specs, and certify for grid or CNG/LNG use.

Delivery options for RNG: onsite use, pipeline injection and transport

From a practical renewable natural gas definition standpoint, delivery is flexible: RNG can be used where it’s produced, piped to a user, or blended into the grid. Because upgraded biomethane is pipeline‑quality, it slots into existing gas networks and heavy‑duty fuel infrastructure with minimal changes.

• Onsite utilisation: Run boilers, CHP or compressors directly at the facility after upgrading.

• Pipeline injection: Meet utility specs (typically 96–98% methane), meter and inject into distribution or transmission lines.

• Dedicated pipeline: Short lateral to a nearby industrial user to avoid grid interconnection complexity.

• Vehicle fuel loading: Compress to CNG or liquefy to LNG for dispensing to natural gas vehicles.

Where RNG is used: heat, power, vehicles and industry

Because upgraded biomethane is compositionally comparable to fossil gas, its applications mirror the conventional gas market. RNG serves thermal loads, power generation and transport without equipment changes, and can also supply feedstocks. In short, a practical renewable natural gas definition includes the roles it fulfils across heat, power, vehicles and industry.

• Heat and steam: Run boilers, kilns and dryers for building and process heat.

• Power and CHP: Fuel generators and combined heat and power for dispatchable output.

• Vehicles: Use compressed or liquefied RNG in natural gas vehicles and fleets.

• Industry and feedstocks: Provide process gas and serve as a bio‑product feedstock.

RNG versus conventional natural gas: compatibility and performance

Renewable natural gas is pipeline‑quality biomethane and is fully interchangeable with conventional natural gas in boilers, CHP, process burners and natural gas vehicles—no equipment changes required. With upgrading that delivers typical pipeline specs of ~96–98% methane, RNG provides comparable energy content and combustion performance. It also tends to contain zero to very low levels of heavier hydrocarbons versus fossil gas, aiding clean combustion. As with any grid fuel, meeting local limits on moisture, oxygen/nitrogen and sulphur protects pipelines and engines.

Environmental impact: methane capture and lifecycle emissions

The core climate value of RNG is methane capture. By intercepting biogas from landfills, farms, wastewater and organics, upgrading it, and combusting it as pipeline‑quality biomethane, projects avoid releasing methane—a gas with at least 28× the warming potential of CO₂ and a ~12‑year atmospheric life. Lifecycle emissions then reflect two levers: avoided methane and displacement of fossil gas or diesel. In some cases, counted correctly, projects can be net‑carbon‑negative; they also cut local NOx and particulate pollution versus diesel.

• Avoided methane: Capturing and using biogas prevents high‑GWP emissions at the source.

• Fuel displacement: RNG substitutes for fossil gas or vehicle diesel, lowering lifecycle CO₂e.

• Air‑quality gains: Cleaner combustion reduces NOx and particulates in transport applications.

Managing risks: methane leakage and best practices

Methane leakage can quickly erode the climate benefits of RNG, so prevention, detection and rapid repair are non‑negotiable across collection, upgrading, compression and interconnection. EPA guidance emphasises minimising methane loss from both landfills and anaerobic digesters. In practice, a rigorous renewable natural gas definition only holds if projects control emissions end to end and verify performance with data.

• Source integrity: Tune wells and digesters, maintain seals, and use backups.

• Tight processes: Minimise venting, use closed‑loop depressurisation, and maintain dryness and low oxygen.

• LDAR discipline: Conduct routine leak detection and repair with documented fix timelines.

• Measurement and proof: Meter flows, track balances, and report to verify low losses.

Policy and incentives that shape the RNG market

Policy turns waste methane into bankable projects. In the United States, renewable natural gas qualifies as an advanced biofuel and can earn credits when used as vehicle fuel under the Renewable Fuel Standard, creating a market-based value stream. EPA’s voluntary programmes such as LMOP and AgSTAR support project development by providing data, tools and best practices to cut methane emissions. Beyond federal support, state and local incentives, grants and favourable utility tariffs can lower capex and accelerate interconnection, fuelling wider RNG deployment.

• Renewable Fuel Standard: Credits for RNG used as transportation fuel.

• EPA support: LMOP and AgSTAR resources reduce barriers and improve performance.

• Public incentives: Grants, rebates and local programmes can improve project economics.

RNG in Canada: regulations, utilities and interconnection

In Canada, RNG projects work with provincial regulators and local gas utilities to demonstrate that upgraded biomethane is pipeline‑quality. While requirements vary by province, interconnection typically hinges on verified gas quality—methane in the mid‑ to high‑90s (around 96–98% for pipeline injection), tight limits on moisture, oxygen/nitrogen, hydrogen sulphide and siloxanes—plus continuous monitoring, metering and safe pressure control. Building to recognised codes (e.g., CSA, API, ASME) and framing a clear renewable natural gas definition—biogas upgraded to meet utility specs—helps streamline approvals.

• Align gas quality: Hit methane %, moisture, O₂/N₂, H₂S and siloxane limits with documented sampling/analysers.

• Design to code: Use CSA/API/ASME‑compliant equipment and safety systems for compression and controls.

• Prove and report: Agree on metering, odourisation and performance reporting to support commissioning and ongoing compliance.

Choosing an upgrading technology: what to evaluate

Choosing an upgrading technology hinges on gas‑quality targets, uptime and operating cost. A rigorous renewable natural gas definition implies delivering pipeline‑quality biomethane consistently—typically 96–98% methane with tight limits on H2S, moisture, siloxanes and O2/N2. Prioritise processes and partners that prove compliance on your feedstock and flow variability, not just nameplate claims.

• Methane recovery: Maximise recovery, minimise slip; robust LDAR.

• Contaminant removal: Deep H2S/siloxane control; O₂ polishing to low ppm.

• Efficiency and OpEx: Power draw, media/solvent use, maintenance.

• Flexibility/scale: Turndown, modularity, rapid deployment, CO₂ capture.

• Monitoring/assurance: Online analysers and certification for pipeline/CNG.

Economics of RNG projects: capex, opex and revenue streams

The business case for RNG hinges on capital outlay, operating cost and monetisation. Because the renewable natural gas definition demands pipeline‑quality biomethane, capex concentrates in pretreatment, upgrading and interconnection. Cash flow then depends on power and media costs, uptime and methane recovery, while revenues combine contracted gas sales with policy‑driven credits and, where possible, coproducts.

• Capex drivers: Pretreatment, upgrading, compression, metering/analysis/odourisation, pipeline interconnect or dispenser, plus site works and controls.

• OpEx drivers: Electricity, media/solvent changes, routine maintenance, labour, compliance testing; methane slip is lost sales.

• Revenue streams: Gas offtake contracts; EPA Renewable Fuel Standard credits for vehicle fuel; carbon credits from methane capture; optional CO₂ sales.

Projects that maximise recovery and minimise parasitic loads lift netback and bankability.

Market outlook: adoption and growth trends

Adoption is accelerating as waste‑methane capture scales. EPA data show operating renewable natural gas projects rose to 237 in 2023 (135 agriculture, 102 landfill), up from small numbers in 2005. North America now has 300+ operational facilities. Growth is driven by federal Renewable Fuel Standard credits for vehicle fuel alongside state and local incentives, with LMOP and AgSTAR resources easing development. Expect continued expansion across landfills, livestock farms, wastewater plants and food‑waste digestion.

Key takeaways

RNG is pipeline‑quality biomethane made by upgrading biogas from landfills, farms, wastewater and organic waste. Treatment removes CO2, moisture, H2S and traces to meet grid specs, so it performs like fossil gas across heat, power and vehicles. Its climate value comes from methane capture; success hinges on leakage control, gas quality compliance, solid offtake and policy.

• Gas quality first: meet methane, moisture, O2 and H2S limits.

• Minimise leakage: closed systems, LDAR and rapid repair discipline.

• Plan delivery: onsite use, pipeline injection or vehicle fuel.

• Stack revenues: gas sales plus eligible credits where applicable.

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