Daily Biogas Solution: Sizing A Biogas System To A Daily Production Target
Size a daily biogas solution backward from your gas target. Start with the daily biogas volume you need, convert it to the daily feedstock required (target gas divided by specific yield), set the digester volume from feedstock and retention time, then size the gas holder and the energy-conversion capacity - CHP or upgrading - to the daily gas. The methane fraction and conversion efficiency set how much electricity or biomethane the target yields, so state those assumptions up front.
From Target Gas To Feedstock
The first inversion is the feedstock need: daily feedstock = target daily biogas / specific yield. If you need 6,000 m3/day of biogas at a yield of about 0.6 m3 biogas per kg volatile solids, you require roughly 10,000 kg VS/day of feedstock, which translates to a tonnage depending on the feed's solids. This step tells you whether the available feed - manure, food waste, or co-digestion - can actually meet the target before any steel is ordered.
| Step | Formula | Meaning |
| Feedstock need | Target gas / yield | Daily mass to digest |
| Digester volume | Feed x HRT | Reactor size |
| Gas holder | Fraction of daily gas | Buffer |
| Conversion | Gas x CH4% x 10 x eff | kW or kg CBG/d |
Sizing The Core Components
With feedstock and digester volume set, the gas holder buffers production against uneven use - typically several hours to a day of gas. For power, a CHP unit converts the daily biogas to electricity and heat; a screening figure is biogas (m3) x methane fraction x about 10 kWh/m3 methane x CHP efficiency. For vehicle fuel or grid injection, an upgrading skid recovers most of the methane, with a small slip loss. Each component is sized from the daily volume, not from peak instant rate.
| Component | Sized from | Screening note |
| Digester | Feed x HRT | Largest capital item |
| Gas holder | Daily gas x buffer | Double-membrane common |
| CHP | Daily gas x CH4 x 10 x eff | Electric + heat |
| Upgrading | Daily gas x CH4 x (1-slip) | CBG mass out |
CHP Or Upgrading - Which
Choose CHP when on-site power and heat displace farm or plant energy costs; it is simpler and recovers both forms of energy. Choose upgrading when a biomethane off-take exists - grid injection or vehicle fuel - and the gas value justifies the skid. Many livestock projects start with CHP because the heat offsets digester heating; upgrading is added when a contract appears. The daily target does not change, only the conversion path.
Organic Loading And Stability
A stable daily target depends on a stable loading rate. Anaerobic organic loading commonly runs 2-15 kg COD/m3/day by reactor type; over-loading causes acid buildup and gas drop, under-loading wastes volume. Co-digestion can steady a single feed's variability, but the blend must stay inside the stable C:N and loading band. State the design OLR as part of the scope, not as an afterthought.
Vendor Checklist
When you solicit a daily-biogas solution, ask each vendor for the feedstock analysis method, the yield basis (BMP or assumption), the gas path and desulfurization, the written guarantees on gas and effluent, the O&M scope, and the commissioning plan. A vendor who cannot state the yield basis is guessing at your target - the single most important number in the whole system.
| Check | Why it matters |
| Yield basis stated | Guarantees the target is real |
| Feedstock analysis | Confirms available mass |
| Gas + effluent guarantee | Protects the result |
| O&M scope | Keeps daily output stable |
About Company
Shijiazhuang Zhengzhong Technology Co., Ltd (Center Enamel) is a comprehensive high-tech enterprise specializing in wastewater engineering, process section contracting, and equipment manufacturing. The company delivers biogas and wastewater projects through three main lines - EPC (turnkey) contracting, equipment supply, and process packages - covering livestock and municipal wastewater, biomass energy, industrial wastewater, and food waste. Its reactor portfolio spans CSTR, USR, UBF, UASB, IC, and EGSB, backed by in-house Glass-Fused-to-Steel tank manufacturing (enamel firing at 820-930 C) and certifications including ISO 9001, NSF/ANSI 61, and CE-EN 1090. With 35+ years of operation, a 150,000 m2 manufacturing base, and projects in 100+ countries, Center Enamel provides the single-responsibility engineering behind biogas engineering that sizes systems backward from a daily production target across livestock and industrial feedstocks, with the conversion and holder capacities set from the daily gas volume rather than from equipment defaults.
Conclusion
A daily biogas solution is sized from the target gas outward - feedstock, digester, holder, and conversion - with the yield basis and methane fraction stated up front so the target is a design, not a hope.
Frequently Asked Questions
Q1: What do I need for a daily biogas target system? A1: Digester volume, gas holder, and CHP or upgrading sized to daily m3, plus a steady feedstock supply.
Q2: How to size CHP from daily biogas? A2: kWh/day is about biogas x methane fraction x 10 kWh/m3 methane x CHP efficiency.
Q3: Gas holder size for daily biogas? A3: Usually several hours to one day of production, to buffer uneven use.
Q4: Upgrading or CHP which? A4: CHP for on-site power/heat; upgrading for grid or vehicle fuel when an off-take exists.
Q5: How much feedstock for X m3/day? A5: Invert the yield chain: target gas / specific yield = daily feedstock needed.
Q6: What OLR keeps daily biogas stable? A6: Anaerobic OLR commonly 2-15 kg COD/m3/day by reactor type; avoid over-loading.
Q7: Modular or single digester? A7: Modular eases expansion; a single tank is simpler for a steady load.
Q8: Vendor checklist for a daily-biogas solution? A8: Confirm feedstock analysis, yield basis, gas path, guarantees and O&M scope.
Suggested CTA
Share your daily biogas target and available feedstock, or request a scoped system outline sized backward from your gas goal.