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Biogas Storage Tank
| MOQ: | 1 SET |
| Price: | Please contact us |
| Standard Packaging: | Standard export wooden box |
| Delivery Period: | 5~45 days |
| Payment Method: | L/C,T/T |
| Supply Capacity: | 20 sets per month |
Biogas Storage Tank:
Why Your Plant Needs Two of Them, Not One
Written by the tank and gas-holder engineering team at Sichuan Mondes Green Technology Co., Ltd., the manufacturer of both the GFS bolted digester tanks and the FS-series double-membrane gas holders we build and export. Last updated September 2026. This guide clears up the most common mix-up in biogas procurement, then shows how to size the gas buffer and which numbers to check before you sign.
What a biogas storage tank actually stores
The phrase "biogas storage tank" is the wrong name for half the equipment on a biogas plant, and the confusion costs buyers real money. It lumps together two vessels that do completely different jobs: one holds the liquid digestate, the other holds the gas. Get the distinction wrong and you either over-spec a gas holder you do not need, or forget the gas holder entirely and flare a third of your gas.
The digester tank is the reactor. It holds the warm, mixed, oxygen-free slurry where bacteria turn manure, sludge, or food waste into methane. It is sized on retention time, heated, and built to carry mixers and heating loops.
The gas holder is the buffer. It sits above or beside the digester and stores biogas at near-atmospheric pressure between the moment the bacteria make it and the moment an engine, boiler, or upgrading skid burns it. A plant can run without a digester for exactly zero minutes. It can run without a gas holder for about as long before the flare starts.
The digester tank: GFS bolted vs concrete vs welded steel
The digester is where ordinary storage tanks fail first. Above the liquid line, hydrogen sulfide condensate forms sulfuric acid on any cool surface. Below it, the slurry attacks coatings from within. Three build methods dominate, and they behave nothing alike in biogas service.
Sizing the gas buffer, not the digester
The digester size comes from retention time and feedstock. The gas holder size comes from a different sum: how much gas the bacteria make per hour, and how unevenly your equipment burns it. The volume exists to cover that gap.
Buffer volume (m³) = hourly gas production (Nm³/h) × hours of autonomyThe autonomy number depends on what runs downstream:
- Continuous CHP or boiler: 4 to 6 hours. The holder only smooths feedstock swings and digester hiccups.
- Daytime-only CHP: cover the idle shift. If the engine runs 10 hours and idles 14, you need at least 14 hours of buffer plus margin.
- Batch CNG truck filling: 10 to 16 hours, because gas made overnight waits for the morning shift.
A worked example. A digester makes 250 Nm³/h of raw biogas. Feeding a continuous CHP, it needs 250 × 6 = 1,500 m³ of holder. Feeding a CNG plant on one day shift, it needs closer to 250 × 16 = 4,000 m³. Same digester, two and a half times the holder.
Five numbers that separate a good tank quote from a bad one
Quotes arrive as a volume and a price. The information you actually need is on the coating datasheet and the joint drawing. Ask for these five before you compare:
- Coating thickness and adhesion: 0.25 to 0.4 mm with adhesion above 3,450 N/cm. Below that, the glass layer is thin enough to wear through at the liquid line.
- Holiday test voltage: every panel spark-tested above 1,500 V before dispatch. A pinhole at the liquid line becomes a rust spot, then a leak.
- pH range the coating survives: standard 3 to 11, special formulations to 1 to 14. Match it to your feedstock, not the brochure.
- Gas-tightness proof on the roof: digester duty means the roof and its penetrations hold pressure. Ask for the joint design and a leak-test method, not a promise.
- Panel and joint traceability: plate thickness 3 to 12 mm by tank size, anchor bolts to a named grade, and every panel logged to its holiday-test result.
Three plant-design mistakes we keep fixing
Each one below has reached us as a rescue job, sometimes years after the first order went in.
Bought the digester, forgot the holder
The plant looked balanced on paper until the CHP tripped on lean gas at 4 a.m. and the flare took the difference. Re-running the buffer sum before ordering costs nothing.
Specified a storage tank, got a water tank
A plain bolted tank with no gas-tight roof and no mixer-load rating is not a digester. Retrofitting gas containment onto a vessel never designed for it costs more than doing it once.
Poured concrete, then needed to expand
Mixer torque and thermal cycling cracked the structure, and adding capacity meant building again. Bolted steel grows by adding a course, so capacity follows the contract instead of leading it.
Where biogas storage tanks are used
Why specify through Mondes
Sichuan Mondes Green Technology Co., Ltd. builds the GFS bolted digester tank and the FS-series double-membrane gas holder, so the tank and the roof are designed as one system instead of two suppliers pointing at each other.
Fabrication runs under an ISO 9001:2015 quality system. Panels are factory-coated and holiday-tested, and every unit ships with the coating test data and a roof-joint drawing for your site. Tanks are engineered to AWWA D103-09 and EN ISO 28765; confirm the exact certificates against your duty before purchase.
We would rather tell you when a bolted tank is the wrong call than win a sale and lose a reference. If your duty is high-pressure, flame-exposed, or above the H2S ceiling we rate for, we will say so and point you to the right structure.
Spec your biogas storage system with us
Send us your feedstock, retention time, hourly gas production, and downstream equipment, and you will get a digester size and a gas-holder buffer calculation with the working shown, not a catalogue price per cubic metre. We manufacture the GFS tank and the FS-series holder at Sichuan Mondes Green Technology (ISO 9001).
Email: richie@scmondes.comFrequently asked questions
What is the difference between a biogas digester tank and a gas holder?
The digester tank holds the liquid slurry where bacteria make biogas. The gas holder buffers the gas at low pressure between production and use. One is sized on retention time, the other on your equipment's consumption profile.
How big a gas holder do I need for a 100 kW CHP engine?
A 100 kW engine burns roughly 50 to 60 Nm³/h of biogas. Running continuously, a 4 to 6 hour buffer means about 250 to 350 m³ of holder volume. Daytime-only operation roughly doubles that. Start from your engine datasheet.
Is a GFS bolted tank better than concrete for a biogas digester?
For most farm, municipal, and industrial digesters, yes. The glass coating shrugs off H2S above the liquid line, bolted joints stay gas-tight, and the tank expands by adding courses. Concrete cracks under mixer torque and is hard to relocate.
Can the tank and gas holder be one system?
Yes. A double-membrane holder mounts directly on the digester roof, using the tank as the foundation. Specifying both from one supplier keeps the roof joint, anchor ring, and control cabinet compatible.
How long does a GFS biogas tank last?
With the standard glass coating, design life runs above 30 years, with minimal maintenance and no repainting. The gas holder membrane is a separate wear item, typically replaced around year 10 to 15.
