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Hydrogen Electrolyzer Storage Duration Estimator

This calculator estimates how long a stored energy quantity can support a hydrogen electrolyzer and downstream demand at a selected withdrawal or consumption rate. It converts storage capacity into hours or days of operation and also shows the amount remaining after a user-defined interval.

The estimate is useful for preliminary resilience planning, buffer sizing, and operating schedule discussions. It assumes a constant rate and a fully usable stored quantity; real systems may have minimum inventory, conversion losses, pressure limits, or quality constraints that reduce usable duration.

Storage and demand assumptions

kg
kg/h
%
h
Result
—
Usable storage duration
Usable energy after reserve—
Energy remaining after elapsed time—
Duration in days—

1. Enter usable storage

Use the stored energy available before applying the operating reserve.

2. Enter the operating rate

Use the expected constant consumption or withdrawal rate in the matching unit per hour.

3. Set a reserve

Hold back a percentage for safety, process stability, or minimum inventory.

4. Check remaining energy

Enter an elapsed operating time to see the estimated quantity still available.

5. Review duration

Use the hours and days as a planning estimate and account separately for losses or variable demand.

Usable energy = Stored energy × (1 − Reserve fraction) Duration (hours) = Usable energy ÷ Operating rate Remaining energy = max(0, Usable energy − Operating rate × Elapsed time)

The calculation assumes a constant operating rate and no replenishment during the period.

What the result means

The duration is the estimated time the usable inventory can sustain the entered operating rate.

Actual duration may be shorter when storage or conversion losses, minimum inventory, or variable loads apply.

Given: Stored energy = 1,200 kg, rate = 50 kg/h, and reserve = 10%.

Calculation: Usable energy = 1,200 × 0.90 = 1,080.0 kg. Duration = 1,080.0 ÷ 50 = 21.6 hours.

Result: The stored energy supports approximately 21.6 hours, or 0.90 days, at the selected constant rate.

Should I enter total or usable storage?

Enter the amount available before the reserve percentage is applied. Exclude inventory that can never be withdrawn.

Why include a reserve?

A reserve protects against uncertainty and may represent minimum operating inventory or an emergency margin.

Can the rate change over time?

This calculator assumes a constant rate. For a variable schedule, calculate separate time blocks or use a time-series model.

Does the result include replenishment?

No. Any incoming energy or fuel during operation must be modeled separately.

What happens when elapsed time exceeds duration?

Remaining energy is shown as zero rather than a negative amount.