Hydrogen Backup Storage Sizing Calculator

Dimension on-site hydrogen storage for backup applications. Input critical load, target autonomy window, fuel-cell efficiency, and storage losses to estimate how many kilograms of hydrogen you need—including a configurable safety buffer for cold weather, stack aging, or emergency reserve.

Average electrical demand (kW) you must support during the outage window.
Duration in hours that the hydrogen system must cover without grid power.
Net electrical efficiency from hydrogen to delivered AC power (stack + balance of plant).
Leave blank to assume 8% storage and conversion losses; raise for high-pressure or liquid systems.
Leave blank to assume 33.3 kWh/kg for 350-bar compressed hydrogen; adjust for liquid or LOHC solutions.
Leave blank to apply an 18% contingency on required mass for cold weather or degradation allowances.

Engineering estimator only; confirm sizing with a professional engineer and applicable codes.

Examples

  • Manufacturing plant with 500 kW critical load for 12 hours, 52% fuel-cell efficiency, 10% losses, 33.3 kWh/kg, 18% buffer ⇒ 454.3 kg H₂
  • Edge data center drawing 80 kW for 4 hours, 55% efficiency, 8% losses, 33.3 kWh/kg, 10% buffer ⇒ 20.9 kg H₂

FAQ

How does this compare with battery storage?

Divide the required kWh by your battery system’s usable capacity and round up to the nearest cabinet. Hydrogen often wins beyond 10+ hours of autonomy.

Can I model hybrid configurations?

Yes. Reduce the critical load input by the portion you plan to serve with batteries, then rerun to size the hydrogen component.

What pressure should I assume?

Most on-site systems run 350–700 bar. Adjust the energy density or volume multiplier based on the specification of your storage vessels.

Additional Information

  • Multiply the required mass by 0.042 m³/kg to approximate 350-bar storage volume (e.g., 454 kg ≈ 19 m³ per cascade).
  • Higher pressure or liquid storage reduces footprint but increases cost and boil-off; adjust the loss percentage accordingly.
  • Revisit the safety buffer seasonally—winter derates stacks more than mild climates.
  • Pair this result with your hydrogen production or delivery schedule to confirm refuelling cadence fits operational needs.

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