A time-based balance connects fermentation collection, recovery throughput, liquid inventory and purchased-gas backup.
Annual beer volume is a starting point
Two breweries with the same annual beer output can need different recovery systems. Their fermentation vessels, brewing calendar, collection windows, packaging schedule and CO₂ consumption can differ. A useful sizing study follows a representative production period and records when gas is available, when it meets the collection criteria and when the brewery needs product.
The source profile should show individual or overlapping fermentation batches where practical. The demand profile should include the processes that will use recovered CO₂ and the quality required at those points. Keep purchased gas records in the same time period so seasonal or accounting differences do not create an apparent recovery opportunity that is not present in operation.
Use gas buffering and liquid storage for different tasks
A gas holder can smooth shorter changes between fermentation flow and recovery throughput. Liquid storage balances the amount of product made and withdrawn over a different timescale. Both influence operation, but one cannot be substituted for the other simply by comparing their physical dimensions.
If a source peak is short, additional gas buffering may allow a smaller processing rate to accept more of that peak. If a production pause lasts much longer, liquid inventory or purchased CO₂ may be needed to cover demand. The alternatives should be compared against actual durations, operating constraints and installed cost rather than one average hourly figure.
A simple inventory example
Consider an illustrative plant producing 1,000 kg/h of accepted liquid for 12 hours per day. Production is 12 tonnes per day. If the brewery consumes 500 kg/h continuously for 24 hours, consumption is also 12 tonnes. During the production period, inventory increases by 500 kg/h; during the other 12 hours, it decreases by the same rate. The daily inventory swing is 6 tonnes.
That arithmetic does not select a 6-tonne nominal tank. The vessel’s usable inventory, operating limits, starting stock, delivery arrangements and the desired interruption margin must also be considered. It shows why a balanced daily total still needs storage: production and consumption occur at different times.
Test an unfavorable production day
Now keep recovery at 1,000 kg/h for 12 hours but increase continuous demand to 700 kg/h. Daily demand becomes 16.8 tonnes, leaving a 4.8-tonne shortfall. A larger tank can postpone the shortage if it starts full, but cannot resolve the repeated daily deficit. The operating plan needs more accepted production, lower demand or another supply source.
This distinction is important during packaging peaks, brewery expansion and seasonal brewing changes. Model at least a representative normal period and a credible unfavorable period. Avoid choosing an equipment capacity solely from an annual target if it creates prolonged operation below the intended load range.
Bring quality and backup into the same model
Only gas that is admitted under the agreed collection criteria belongs in the available-feed profile. Air ingress, early fermentation conditions, carryover or other source changes can reduce the usable collection window. A theoretical generation estimate should not silently assume that all generated gas becomes accepted liquid product.
Our project discussion brings together the fermentation calendar, measured off-gas profile, consumption records, existing storage and purchased-gas arrangements. The resulting recovery study can define the intended role of each source, the storage margin and the operating priorities. It also gives the brewery a clearer basis for estimating purchase displacement, because only product that can meet actual demand at the required quality replaces purchased CO₂.
Common technical questions
Can storage make up for permanently insufficient recovery output?
No. It can bridge a timing mismatch or finite interruption, but a repeated average deficit requires another supply or a change in production or demand.
Should all fermentation gas be included as recoverable?
Only the portion available for collection within the agreed source and operating envelope should be counted in a practical recovery estimate.
A daily inventory worksheet
| Period | Accepted recovery | Demand | Change in liquid inventory |
|---|---|---|---|
| 00:00–12:00 | 1,000 kg/h × 12 h = 12 t | 500 kg/h × 12 h = 6 t | +6 t |
| 12:00–24:00 | 0 t | 500 kg/h × 12 h = 6 t | −6 t |
| Daily total | 12 t | 12 t | 0 t; a 6 t working swing remains necessary |
This ideal example excludes storage losses and reserve. If production starts with an empty usable inventory just before the twelve-hour no-recovery period, demand still cannot be met. Starting inventory and event order matter. Repeat the balance with actual batch overlaps, a recovery interruption and a peak-use event before selecting nominal tank volume.
Technical references
- ISBT: Bulk Carbon Dioxide quality and analytical guidance, publication BVG-00001 — The publication covers feed-gas considerations, finished-product impurity levels and analytical methods. The copyrighted publication itself was not reproduced.
- EIGA: Food and beverage gases — Industry context for food and beverage gas applications.
Apply this to your project
Open the source assessment tool to record the mass-balance and economic assumptions. For a project-specific design, share the gas analysis and product specification with us.
We publish this guide as YTC. Our editorial policy explains the source checks, AI assistance and how to report a correction. Examples do not establish a plant guarantee.