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Waste and compost · Design the organics and materials systems · waste-7Decide whether a biogas digester is viable
Small digesters turn manure and some food waste into cooking gas and liquid fertiliser. They only pay off when you have steady feedstock, enough warmth and a real use for the gas, and they are labour intensive.
How
- Feedstock: confirm you will have manure every day (for example cows, pigs or poultry). Household food scraps alone are usually too little for meaningful gas.
- Temperature: one manufacturer rates output in bands: warm above 23 °C, temperate 15 to 23 °C and cold 12 to 15 °C, with much lower gas in colder bands.
- Water: plan for slurry dilution water every day (one manufacturer specifies 1 part fresh cow dung to 2 parts water).
- Size and retention: FAO's extension manual (Nepal programme) gives biogas as 50 to 70 percent methane at about 20 MJ per m3, with cow dung plants fed about 6 kg of dung per m3 of digester per day and a retention time of 50 to 60 days. Use these only as a cross-check on your supplier's sizing.
- Use: confirm a gas appliance (usually a biogas stove) near the digester. Gas you cannot use has no value.
- Estimate gas with the biogas yield calculator. If the result is small or your climate is cold, put the effort into composting instead.
- Record your go or no-go decision and why.
Do these first
Sources
- Micro-Scale Biogas Production: A Beginner's Guide. National Center for Appropriate Technology (NCAT) ATTRA, accessed 2026-11
- Biodigester user manual (B2C, 2021). Sistema.bio (manufacturer), accessed 2026-11
- Anaerobic Digestion of Animal Manures: Methane Production Potential of Waste Materials. Oklahoma State University Extension, accessed 2026-11
- Biogas Technology: A Training Manual for Extension, Session 1: System Approach to Biogas Technology (1996). Food and Agriculture Organization of the United Nations (FAO), accessed 2026-11