How to use this calculator
- Enter inventory that can be discharged under normal limits.
- Enter the steady delivery rate required by the load.
- Set the inventory reserve that must remain.
- Calculate the no-recharge duration.
#1204 · Energy & Environment Tool
Biomass Boiler Storage Duration Calculator
Estimate how long stored heat can support a steady delivery rate without recharging. Enter usable inventory, the rate delivered to the load, and the reserve percentage that must remain unavailable. The calculator reports discharge duration, deliverable inventory, and the equivalent daily delivery rate. It is best for first-pass storage planning; variable loads, recharge, pressure constraints, and equipment limits require a time-series model.
Calculator
Storage dischargeFormula
Deliverable inventory = usable inventory × (1 − reserve fraction)
Storage duration = deliverable inventory ÷ delivery rate
Storage duration = deliverable inventory ÷ delivery rate
What the result means
The result is the number of hours the entered inventory can sustain the selected delivery rate while preserving the reserve. Lower delivery rates extend duration proportionally.
This simplified estimate assumes constant delivery, no recharge, and no additional standing or conversion losses.
Example calculation
6 MWhth with a 10% reserve leaves 5.4 MWhth. At 1.2 MWth, storage duration is 4.50 hours.
Tips for better results
- Use deliverable rather than nameplate inventory.
- Keep reserve policy explicit.
- Test peak and average delivery rates separately.
- Account for standing losses in the usable-inventory estimate.
- Use hourly simulation when load or recharge varies.
Frequently asked questions
What does usable thermal storage mean?
Enter inventory that can actually be withdrawn within operating limits, before applying the selected reserve.
Should reserve inventory be included?
Yes. The reserve percentage is withheld from deliverable inventory and reduces the reported duration.
Does the result include recharge or production during discharge?
No. This is a no-recharge duration; simultaneous production must be modeled separately.
What happens if the delivery rate changes over time?
Use a time-weighted average or calculate separate operating stages.
Does storage duration include conversion losses?
Enter usable inventory after expected losses, or adjust the inventory input to represent them.
Related calculators
Storage variables
| Variable | Effect |
|---|---|
| Usable inventory | Raises duration in direct proportion |
| Reserve | Reduces deliverable inventory |
| Delivery rate | Higher rate shortens duration |