♻ Renewable Natural Gas (RNG) Calculators

10 calculators for biogas feedstock yield, cleanup, upgrading, pipeline injection, and credit economics — built for engineers developing landfill, dairy, WWTP, and food-waste RNG projects.

10 calculators · LandGEM v3.03 · IPCC 2019 Tier-2 · AGA Report 4A · CARB LCFS · EPA RFS 40 CFR 80.1426

1. Biogas Feedstock Yield

Estimate methane generation from the three primary RNG feedstocks: landfill, dairy manure, and WWTP/food-waste digesters.

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Landfill Gas Yield

LandGEM v3.03 · 40 CFR 60 XXX/Cf

EPA LandGEM first-order decay summation for annual landfill methane generation, peak-year rate, captured CH₄ for RNG, and NMOC mass flux.
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Dairy Manure Biogas Yield

IPCC 2019 Tier-2 · EPA AgSTAR

Anaerobic-digester biogas yield with LCFS avoided-baseline credit, volatile solids loading, and methane potential per IPCC Tier-2 method.
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WWTP / Food-Waste Digester

Metcalf & Eddy 5e · 40 CFR 503

WWTP and food-waste anaerobic digester biogas yield with Class A/B biosolids assessment and Liu correlation for volatile solids destruction.

2. Biogas Cleanup (Trace Contaminants)

Size scavenger beds for H₂S and siloxane removal to meet pipeline-spec gas-quality requirements.

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H₂S Scavenger Bed Sizing

Iron sponge / SulfaTreat / SulfaTrap · GPSA 14e

Dry-media H₂S scavenger bed sizing for biogas cleanup, breakthrough capacity, and bed life calculation to meet pipeline spec.
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Siloxane Removal Bed Sizing

Coal GAC / coconut shell / silica gel

Silicon-basis activated carbon and silica gel bed sizing to remove D4/D5 siloxanes from landfill and WWTP biogas for engine/turbine protection.

3. Biogas Upgrading to Pipeline-Quality RNG

CO₂ removal sizing for the two dominant technology choices: PSA and membrane.

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PSA Biogas Upgrading

CMS / 13X / 4A · Yang-Ruthven

Pressure swing adsorption sizing for biogas upgrading to pipeline RNG (≥96% CH₄), methane recovery, and bed cycle design.
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Membrane Biogas Upgrading

Evonik SEPURAN / Air Liquide MEDAL

Polymer membrane sizing with specific-area method for polyimide, cellulose acetate, and polysulfone technologies. Includes methane slip estimate.

4. Pipeline Injection & Project Economics

Tariff compliance, carbon credit pathways, and the full project economics stack for D3 RINs and LCFS.

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RNG Pipeline Injection Station

AGA Report 4A · Wobbe / HHV / SG

Gas-quality blending for tariff compliance with Wobbe Index, HHV, specific gravity, and methane number per AGA 4A.
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LCFS Pathway CI

CA-GREET 3.0 · 17 CCR §95488

CARB LCFS pathway carbon intensity scoring for RNG (dairy, landfill, WWTP, food waste). Tier-2 method with avoided emissions credits.
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D3 RIN + LCFS Economics

EPA RFS 40 CFR 80.1426 · NPV/IRR

Stacked-revenue project DCF for D3 RIN + LCFS + brown gas market stack. NPV, IRR, simple payback, and sensitivity analysis.

Industry Standards Implemented

  • EPA LandGEM v3.03 — Landfill methane generation model
  • IPCC 2019 Refinement — Tier-2 manure methane EF
  • Metcalf & Eddy 5e — WWTP digester sizing (Liu correlation)
  • 40 CFR 503 — Class A/B biosolids assessment
  • GPSA Engineering Data Book 14e — H₂S scavenger sizing
  • AGA Report 4A — Natural gas calorific value & Wobbe
  • CARB LCFS — 17 CCR §95488 — Pathway CI scoring
  • EPA RFS — 40 CFR 80.1426 — D3 RIN generation
  • CA-GREET 3.0 — Lifecycle GHG model
  • Yang & Ruthven (2008) — PSA equilibrium & kinetics