Biogas Yield Calculator

Enter Digester and Feedstock Inputs

The calculator uses a responsive input grid: three columns on large screens, two on medium screens, and one on mobile.

Wet feedstock input (kg/day)

Total solids, TS (%)

Volatile solids of TS (%)

VS destruction efficiency (%)

Specific biogas yield (m³/kg VS destroyed)

Methane content in biogas (%)

Hydraulic retention time, HRT (days)

Target slurry solids after dilution (%)

Slurry density (kg/m³)

Electrical conversion efficiency (%)

Parasitic electrical load (%)

Methane lower heating value (MJ/m³)

Example Data Table

Wet Feed (kg/day)	TS (%)	VS of TS (%)	VS Destroyed (%)	Specific Yield	Methane (%)	HRT (days)	Biogas (m³/day)	Net Electricity (kWh/day)	Digester Volume (m³)
1000	18	82	55	0.85 m³/kg VS destroyed	60	30	69.00	122.48	54.00

This example uses the same default values prefilled in the calculator so users can validate the method quickly.

Formula Used

1) Dry solids input: Dry Solids = Wet Feedstock × TS fraction

2) Volatile solids input: VS Input = Dry Solids × VS fraction of TS

3) Volatile solids destroyed: VS Destroyed = VS Input × VS destruction fraction

4) Biogas production: Biogas = VS Destroyed × Specific Biogas Yield

5) Methane production: Methane = Biogas × Methane fraction

6) Methane energy: Energy (MJ/day) = Methane × Methane LHV

7) Energy conversion: Energy (kWh/day) = Energy (MJ/day) ÷ 3.6

8) Gross electricity: Gross Electricity = Methane Energy in kWh × Electrical efficiency

9) Net electricity: Net Electricity = Gross Electricity × (1 − Parasitic load fraction)

10) Water addition: Water = (Dry Solids ÷ Target slurry solids fraction) − Wet Feedstock

11) Slurry flow: Slurry Volume = Prepared Slurry Mass ÷ Slurry Density

12) Digester volume: Digester Volume = Slurry Volume per day × HRT

13) Organic loading rate: OLR = VS Input ÷ Digester Volume

How to Use This Calculator

Enter the wet feedstock mass supplied to the digester each day.
Provide total solids and volatile solids percentages from lab data or literature values.
Enter the expected volatile solids destruction level for the process.
Use a realistic specific biogas yield for the selected substrate blend.
Enter methane fraction to estimate usable fuel quality and energy value.
Set the target slurry solids and density to estimate dilution demand.
Enter HRT to calculate the working digester volume required.
Add generator efficiency and parasitic load if power recovery is planned.
Click the calculate button to show results above the form.
Download the generated result table as CSV or PDF when needed.

Frequently Asked Questions

1) What does this calculator estimate?

It estimates daily biogas output, methane volume, energy recovery, dilution water demand, slurry flow, organic loading rate, digestate mass, and required digester volume from feedstock and process inputs.

2) Why is volatile solids important?

Volatile solids represent the biodegradable share of feedstock. Biogas forms mainly from destroyed volatile solids, so this value strongly affects gas volume, methane output, and digester loading.

3) What is a reasonable methane percentage?

Many digesters operate near 50% to 65% methane, depending on feedstock, process stability, retention time, and carbon dioxide content. Higher methane means better fuel quality.

4) Why does target slurry solids matter?

Target slurry solids controls dilution water demand and daily slurry flow. Lower solids improve pumping and mixing, but increase digester volume and heating requirements.

5) What does hydraulic retention time affect?

Hydraulic retention time directly affects required digester volume. A longer retention time increases reactor size, while a shorter value reduces size but may limit conversion.

6) Is electrical output the same as methane energy?

No. Methane energy is the fuel energy available in the gas. Electrical output depends on generator efficiency, and net output also subtracts parasitic site consumption.

7) Can I use blended feedstocks?

Yes. Use weighted average values for solids, volatile solids, methane fraction, and yield, or run separate cases to compare the effect of different feed blends.

8) Should I use lab results or literature values?

Lab data is better for design decisions because real feedstocks vary. Literature values are useful for screening studies, feasibility checks, and early planning.