Estimate what a farm anaerobic digester can produce from cattle manure: daily biogas, electricity, annual revenue, and how long it takes to pay back the investment.
Enter cattle count, manure per head, gas yield, biogas calorific value, generator efficiency, installed cost and electricity price. The tool outputs daily gas, daily kWh, annual kWh, annual revenue, payback and slurry output.
✓ Expert Reviewed: This calculator and its content have been reviewed by agricultural experts. Formulas are based on standard extension service recommendations and the Farm Financial Standards Council. For site-specific advice, consult your local agronomist or extension agent.
Enter the number of cattle, the average manure produced per head per day, the gas yield per kg of manure (typically 0.03-0.05 m³/kg), the biogas calorific value (~6 kWh/m³), generator efficiency (~35%), installed plant cost, and local electricity price. Click Calculate.
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Daily gas = cattle × kg manure/head × gas yield (~0.03-0.05 m³/kg dung). Electricity = gas × calorific value × generator efficiency. Annual revenue = daily kWh × 365 × price. Payback = cost ÷ annual revenue. Slurry ≈ 90% of input mass. For 100 head, 25 kg/head, 0.04 m³/kg, 6 kWh/m³, 35% efficiency, $120,000 cost, $0.18/kWh: daily gas = 100 m³, daily kWh = 210, annual 76,650 kWh, revenue $13,797, payback ~8.7 years. Common mistakes: overestimating gas yield, ignoring O&M costs (1-3%/yr), and assuming all gas is used productively.
A dairy cow produces roughly 40-50 kg manure/day, yielding about 1.5-2.5 m³ of biogas, which is roughly 9-15 kWh of thermal energy. Beef cattle produce less per head (lower feed intake). Actual yield depends on feedstock and digester temperature.
On well-managed operations with good feedstock and a feed-in tariff, payback often ranges 6-12 years. Small farm-scale units struggle to reach the economies of scale; revenue from electricity alone is rarely enough, so heat sales, digestate sales and carbon credits matter.
Digestate is the stabilized, odorless residual material. It is a valuable nutrient-rich fertilizer that can replace synthetic N-P-K, improves soil organic matter, and is easier to store and inject than raw manure.
Mesophilic digesters (35°C) run year-round with heating in cold climates; unheated ambient digesters work only in warm regions and slow in winter. Heating adds energy demand but keeps gas production steady.
High upfront capital, the need for consistent feedstock, O&M expertise, and offtake pricing. Many projects succeed only with grants (USDA REAP, state programs), feed-in tariffs, or partnerships with nearby food-waste producers.