Daily Biogas
64 cu ft
Cooking
6.4 hrs
Digester
482 gal
Savings/yr
$458
Daily Biogas Output
64 cu ft
38,250 BTU/day
Cooking
6.4 hrs
Electricity
3.2 kWh
Inputs
Result
Raw: 50 x 1.5 = 75 cu ft. Warm climate factor 0.85: 75 x 0.85 = 63.8 cu ft. Cooking: 64/10 = 6.4 hrs. Propane equivalent: 64 x 600 / 91,500 = 0.42 gal/day x 365 x $3 = $457.
Inputs
Result
Raw: 25 x 3.0 = 75 cu ft. Temperate factor 0.6: 75 x 0.6 = 45 cu ft. Cooking: 45/10 = 4.5 hrs.
Biogas yield depends on waste type: chicken manure produces ~2.5 cu ft per pound, pig manure ~2.0 cu ft/lb, cow manure ~1.5 cu ft/lb. A homestead producing 50 lbs/day of cow manure generates ~75 cu ft of biogas daily in warm climates, enough for 4–5 hours of cooking.
Digester size equals daily slurry volume times retention time. For 50 lbs/day of manure mixed 1:1 with water, the slurry is about 12 gallons/day. With a 40-day retention time (fixed dome), the digester needs 480 gallons (~64 cu ft). IBC tote digesters hold 275 gallons each.
| Digester Type | Retention Days | Cost per Cu Ft | Best For |
|---|---|---|---|
| Fixed Dome | 40 | $8 | Permanent installation |
| Floating Drum | 35 | $10 | Easy maintenance |
| Plug Flow | 30 | $5 | Large-scale farms |
| IBC Tote | 45 | $3 | DIY beginners |
Yes, 10 cu ft of biogas provides about 1 hour of cooking on a standard burner. A family producing 75–100 cu ft/day from a small digester can cook 7–10 hours daily, replacing 200–300 gallons of propane per year ($600–$900 savings at $3/gal).
Temperature dramatically impacts biogas output. Mesophilic bacteria work best at 95–105°F. In tropical climates (>77°F avg), digesters run at 100% efficiency. In temperate zones (50–65°F), output drops to ~60%. Cold climates (<50°F) see only 35% of potential output unless the digester is insulated or heated.
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Last Updated: Mar 20, 2026
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