Biogas Yield Calculator

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Walk-through

How to Use This Calculator

3 steps

1

Pick a feedstock and enter its mass

Choose Dairy Manure, Food Waste, or Crop Residue from the feedstock dropdown — this fills in typical volatile-solids (VS%) and biogas-potential defaults for that material. Then enter the daily feedstock mass you're feeding the digester (kg/day or lb/day). Switch to Custom if you have lab-measured VS% and biogas-potential figures for your own feedstock.

2

Check the biogas yield and methane split

The result card shows the daily biogas yield in cubic meters, along with the VS mass, methane volume, and energy equivalent. The Biogas Yield tab breaks down the formula step by step; the Methane Content tab shows how much of that biogas is usable methane at your set methane percentage.

3

Compare scenarios and check sizing notes

Adjust volatile solids, biogas potential, or methane content to see how the yield changes — a 5-point swing in VS% or methane content can shift output noticeably. The Energy Equivalent tab converts methane volume to kWh/day and flags what a real digester design still needs (retention time, tank volume, heating).

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Reference

Formula & Methodology

2 formulas

Biogas yield

Biogas (m³/day) = Feedstock mass (kg/day) × VS% × Biogas potential (m³/kg VS)

Volatile solids (VS) is the organic, biodegradable fraction of the feedstock. Multiplying feedstock mass by VS% gives the mass of VS available to microbes each day; multiplying that by the feedstock's biogas potential (cubic meters of biogas produced per kilogram of VS destroyed) gives the daily biogas yield.

Methane volume and energy equivalent

Methane (m³/day) = Biogas × Methane% · Energy (kWh/day) = Methane × 9.94 kWh/m³

Biogas is roughly 50-70% methane by volume, with the remainder mostly CO2. Multiplying biogas volume by the methane percentage gives usable methane volume; multiplying methane volume by methane's lower heating value (~9.94 kWh per m³, per DOE Bioenergy Technologies Office figures) converts that to an energy equivalent.

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Glossary

Key Terms Explained

7 terms

Biogas The gas mixture produced by anaerobic digestion of organic matter — mostly methane (CH4) and carbon dioxide (CO2), with trace hydrogen sulfide and water vapor.

Anaerobic digestion The biological process where microbes break down organic material in an oxygen-free environment, producing biogas as a byproduct. Used in farm digesters, wastewater treatment, and food-waste diversion.

Volatile solids (VS) The organic, biodegradable fraction of a feedstock's total solids — the portion microbes can actually convert into biogas. Expressed as a percentage of wet feedstock mass or of total solids, depending on convention.

Methane content The percentage of biogas that is methane (CH4) rather than carbon dioxide or other trace gases. Typically 50-70%, with 55-65% most common for manure and food-waste digesters.

Feedstock The organic input material fed into a digester — commonly livestock manure, food waste, crop residue, or a blend (co-digestion) of these.

Digester The sealed, oxygen-free tank or lagoon where anaerobic digestion happens. Digesters are sized by feedstock volume and hydraulic retention time, not just daily biogas yield.

Biogas potential A feedstock-specific yield factor — cubic meters of biogas produced per kilogram of volatile solids destroyed (m³/kg VS). Varies by feedstock composition, digester temperature, and retention time.

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Scenarios

Real-World Examples

3 worked examples

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Dairy farm digester

A 500-cow dairy farm feeds 20,000 kg/day of manure into a covered lagoon digester.

Feedstock Dairy Manure Feedstock mass 20,000 kg/day Volatile solids 8% Biogas potential 0.35 m³/kg VS Methane content 60%

VS mass is 1,600 kg/day (20,000 × 8%), yielding 560 m³/day of biogas (1,600 × 0.35) and 336 m³/day of methane (560 × 60%) — about 3,340 kWh/day of energy equivalent, enough to power farm equipment or feed a combined-heat-and-power unit.

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Food-waste co-digestion

A commercial food-waste hauler delivers 5,000 kg/day of pre-processed food scraps to a municipal digester.

Feedstock Food Waste Feedstock mass 5,000 kg/day Volatile solids 20% Biogas potential 0.5 m³/kg VS Methane content 60%

VS mass is 1,000 kg/day (5,000 × 20%), yielding 500 m³/day of biogas — comparable output to the dairy example from a quarter of the feedstock mass, because food waste has both higher VS% and higher biogas potential than manure.

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Energy equivalent check

A digester operator wants to know what 300 m³/day of methane is worth in electricity terms.

Methane volume 300 m³/day Energy content 9.94 kWh/m³

300 m³/day × 9.94 kWh/m³ ≈ 2,982 kWh/day of energy equivalent. After generator efficiency losses (typically 35-40% for a biogas-fueled genset), that translates to roughly 1,050-1,190 kWh/day of usable electricity.

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Deep Dive

Understanding the Biogas Yield Calculator

3 chapters · 4 min read

This calculator estimates the daily biogas a digester will produce from a feedstock's volatile-solids content and biogas potential — the two numbers that drive anaerobic-digestion output. It's built for farmers sizing a manure digester, food-waste operators evaluating co-digestion, and students learning the underlying formula, not as a substitute for a full digester engineering study.

How the Biogas Yield Calculator works

The calculation follows the standard anaerobic-digestion yield model: multiply feedstock mass by its volatile-solids percentage to get the mass of biodegradable organic matter fed in each day, then multiply that by the feedstock's biogas potential (cubic meters of biogas per kilogram of VS destroyed) to get daily biogas volume. Methane volume follows by applying the methane-content percentage, and energy equivalent follows by multiplying methane volume by its lower heating value (~9.94 kWh/m³). VS% and biogas-potential figures come from EPA AgSTAR and FAO anaerobic-digestion reference ranges for common feedstocks.

Inputs and what they mean

Feedstock mass is the daily wet-weight input to the digester. Volatile solids (VS%) is the biodegradable organic fraction of that mass — typically 6-10% for dairy manure, 15-25% for food waste, and 35-45% for dry crop residue. Biogas potential (m³/kg VS) reflects how readily that feedstock's organic matter converts to biogas — food waste and fats convert more efficiently than fibrous crop residue. Methane content, usually 55-65%, determines how much of the biogas is usable fuel versus CO2.

Limits and edge cases

This is a yield estimate, not a digester design. It doesn't account for hydraulic retention time, digester temperature, mixing, or inhibitors (ammonia, excess salts) that can suppress real-world yield below the theoretical potential. Feedstock composition varies significantly by source — always confirm VS% and biogas potential with lab testing or a feedstock supplier before sizing hardware or making financial projections, and consult a digester designer for retention-time and tank-volume requirements.

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Questions

Frequently Asked Questions

6 questions

What formula does the Biogas Yield Calculator use?+

Biogas volume (m³/day) = feedstock mass × volatile-solids percentage × biogas potential (m³ biogas per kg VS destroyed). Methane volume is that biogas volume multiplied by the methane-content percentage, and energy equivalent is methane volume multiplied by ~9.94 kWh per cubic meter of methane.

What are volatile solids and why do they matter?+

Volatile solids (VS) are the organic, biodegradable fraction of a feedstock — the part microbes can actually break down into biogas during anaerobic digestion. Everything else (ash, minerals, inert material) doesn't contribute to gas production, so VS% is the single most important input for estimating yield.

What methane content is typical for biogas?+

Most agricultural and food-waste digesters produce biogas that's roughly 55-65% methane, with the remainder mostly carbon dioxide and trace hydrogen sulfide. Manure-fed digesters often run near 60%; food-waste and high-fat feedstocks can push slightly higher.

What feedstock types does this calculator support?+

The dropdown includes presets for dairy manure, food waste, and crop residue, each with typical volatile-solids and biogas-potential defaults drawn from EPA AgSTAR and FAO reference ranges. Select Custom to enter your own lab-tested or supplier-provided figures for any other feedstock or a blended (co-digestion) mix.

How is the energy equivalent calculated?+

Methane's lower heating value is approximately 9.94 kWh per cubic meter (about 35.8 MJ/m³, per DOE Bioenergy Technologies Office figures). Multiplying daily methane volume by that constant gives the raw thermal energy equivalent — actual usable electricity will be lower after generator or boiler efficiency losses.

Does this calculator size a digester?+

No — it estimates daily biogas yield only. Sizing an actual digester tank also requires a hydraulic retention time (commonly 15-30 days for mesophilic digestion), tank volume to hold that feedstock for the retention period, and a mixing and heating plan. Work with a digester designer for those calculations.

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Feedstock & digester inputs

Formula breakdown

Methane content scenarios

Energy equivalent & digester sizing

Daily biogas yield

How to Use This Calculator

Pick a feedstock and enter its mass

Check the biogas yield and methane split

Compare scenarios and check sizing notes

Formula & Methodology

Key Terms Explained

Real-World Examples

Dairy farm digester

Food-waste co-digestion

Energy equivalent check

Understanding the Biogas Yield Calculator

How the Biogas Yield Calculator works

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

Biogas Yield Calculator

Feedstock & digester inputs

Formula breakdown

Methane content scenarios

Energy equivalent & digester sizing

Daily biogas yield

How to Use This Calculator

Pick a feedstock and enter its mass

Check the biogas yield and methane split

Compare scenarios and check sizing notes

Formula & Methodology

Key Terms Explained

Real-World Examples

Understanding the Biogas Yield Calculator

How the Biogas Yield Calculator works

Inputs and what they mean

Limits and edge cases

Frequently Asked Questions

Get a branded PDF of your results

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