#1149 · Energy & Environment Tool

Thermal Storage Storage Duration Calculator

Estimate the thermal storage storage duration using transparent inputs tailored to thermal storage planning. The calculator returns a main estimate plus supporting values so you can check assumptions, compare scenarios, and identify the variables that most affect the result. Use measured project data when available; early-stage defaults are only a starting point and should be replaced before making an investment or engineering decision.

Calculator

Project assumptions
MWh
Energy available at the point of discharge.
MW
Constant power assumed during discharge.
%
Capacity intentionally held back.
%
Expected reduction from temperature, age, or operating limits.

How to use this calculator

  1. Enter the system values using a consistent measurement boundary.
  2. Replace the example defaults with measured data or documented assumptions.
  3. Select Calculate and review both the main result and supporting metrics.
  4. Change one assumption at a time to compare realistic scenarios.

Formula

Duration = capacity × (1 − reserve) × (1 − derating) ÷ discharge power

The calculation assumes constant power and does not include recharge time.

What the result means

The result is the constant-load support time after reserve and derating adjustments.

Planning estimate only. Confirm equipment limits, degradation, auxiliary consumption, site conditions, tariffs, financing, tax treatment, and safety requirements with qualified professionals.

Example calculation

For 400 MWh, 100 MW, a 10% reserve, and 5% derating, available energy is 342 MWh and duration is 3.42 hours (205 minutes).

Tips for better results

  • Use the same system boundary for every energy and power value.
  • Base availability and efficiency on vendor guarantees or measured data.
  • Test conservative, expected, and optimistic assumptions.
  • Keep reserve, auxiliary load, and degradation assumptions explicit.
  • Do not treat nameplate ratings as guaranteed delivered performance.

Frequently asked questions

Does the thermal storage storage duration estimate include charging losses?

Only losses represented by the efficiency or derating input are included. Add upstream losses to the relevant input assumption when needed.

Can I use partial operating cycles in this storage duration calculation?

Use annual output or operating assumptions that already reflect partial cycling and actual dispatch.

How should degradation be handled for thermal storage?

Use a current usable-capacity value for a single-year estimate, or include a degradation assumption when the calculator provides one.

Does this result replace an engineering or financial study?

No. It is a planning estimate and does not model every control limit, tariff, tax, financing, safety, or site-specific constraint.

Why might actual thermal storage storage duration differ from this result?

Dispatch strategy, ambient conditions, auxiliary loads, downtime, control limits, prices, and measurement boundaries can all change actual performance.

Duration inputs

VariableUnitMeaning
CapacityMWhUsable stored energy
LoadMWConstant discharge demand
Reserve%Energy held back
Derating%Operating reduction

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