Hydrogen Electrolysis Calculator

Calculator Inputs

System Name

Current (A)

Stack Voltage (V)

Operating Time

Time Unit

Faradaic Efficiency (%)

Active Cells in Stack

Molar Gas Volume (L/mol)

Electricity Cost ($/kWh)

Reset

Enter total stack voltage, operating current, active cells, and Faradaic efficiency. Production uses Faraday’s law and reports hydrogen, oxygen, water demand, energy use, and cost.

Example Data Table

Example Case	Current	Voltage	Time	Efficiency	Cells	H₂ Mass	H₂ Volume	Energy
Pilot Stack	150 A	48 V	4 h	95%	20	0.428727 kg	4766.893 L	28.800000 kWh
Bench Test	25 A	12 V	2 h	92%	8	0.034727 kg	386.205 L	0.600000 kWh

Formula Used

Overall reaction
2H₂O(l) → 2H₂(g) + O₂(g)

Total charge
Q = I × t

Hydrogen moles across the stack
n(H₂) = (Q × η × N) / (2 × F)

Hydrogen mass
m(H₂) = n(H₂) × 2.01588 g/mol

Hydrogen volume
V(H₂) = n(H₂) × molar gas volume

Water consumed
m(H₂O) = n(H₂) × 18.01528 g/mol

Electrical energy
E(kWh) = (V × I × t in hours) / 1000

Specific energy
Specific Energy = E(kWh) / Hydrogen Mass(kg)

Here, F is Faraday’s constant, η is Faradaic efficiency as a fraction, and N is the number of active cells.

How to Use This Calculator

Enter a system name to label your run.
Type the operating current in amperes.
Enter total stack voltage in volts.
Provide the operating time and choose its unit.
Set the Faradaic efficiency percentage.
Enter the number of active cells in the stack.
Choose a molar gas volume basis, such as 22.414 L/mol.
Add electricity cost if you want cost estimation.
Click the calculate button.
Review hydrogen output, water demand, efficiency, energy use, cost, and the graph. Export the results as CSV or PDF if needed.

FAQs

1) What law drives the hydrogen estimate?

Faraday’s law links electric charge to chemical production. The calculator converts charge into hydrogen moles, then applies Faradaic efficiency and active cell count before reporting mass and gas volume.

2) Why do I need to enter active cells?

Each active cell in a stack produces gas at the same current. Total stack hydrogen therefore scales with the number of working cells under similar operating conditions.

3) Should I enter stack voltage or single-cell voltage?

Enter total stack voltage. Hydrogen output depends mainly on current, time, efficiency, and cell count, while energy use depends on current multiplied by total operating voltage.

4) Why can gas volume change without changing mass?

Mass depends on moles of hydrogen. Gas volume also depends on the selected molar volume basis, which changes with temperature and reporting conditions such as STP.

5) Does the calculator include compression or drying losses?

No. It estimates electrochemical hydrogen production and electrical input only. Add compression, purification, cooling, drying, and other auxiliary loads separately for plant-wide studies.

6) How is water demand calculated?

Water demand follows stoichiometry. One mole of water yields one mole of hydrogen, so the calculator converts hydrogen moles into equivalent water mass and approximate liters.

7) Can I use this for PEM and alkaline systems?

Yes, for first-pass estimates. Faraday-based production works well for PEM and alkaline electrolyzers when you enter realistic current, voltage, efficiency, and cell-count values.

8) Are the results guaranteed plant outputs?

No. These are analytical estimates for planning and education. Actual performance depends on crossover, temperature, pressure, degradation, controls, maintenance, and measurement basis.