Using Faraday's Law to determine efficiency of a Hydrogen Generator

How To use Faraday's Law to determine

efficiency of a Hydrogen Generator

If you know the Volts, Amps, Operating Temperature and Production in liters you can determine the efficiency of any Hydrogen Generator. This web page will walk you though how to calculate the efficiency and compare systems. Most well built system will have an efficiency of about 70%.

1. Determine the gram equivalent weight of O2 according to the half reaction:

2H2O----> O2 + 2H2+ + 4 e-

GEW of O2 = molecular weight of O2 / 4

GEW or (M/z) = 2(16)/4 = 8 grams/eq

2. Plug in the time in the amps, seconds and the GEW of O2 into Faraday formula:

M= (Q/F) (M/z)

Weight deposited or released at an electrode = (Current in amps) (time in sec) /96,500 ( F) (coulomb of charge is required to liberate 1Gram

equivalent) (GEW of substance deposited)

So let’s say your generator runs for 1 minute at 20 amps.

W=wt O2 deposited = (X amps) (time in seconds)/ 96,500 (8)

= (20) (60 ) /96,500 (8)

= 0.0995 grams O2

(Note the standard potential of the water electrolysis cell is 1.24 V @ 25 C)

3. Convert grams to moles of O2

0.0995 grams X 1 mole / 32 grams = 0.003 moles O2

We also know that for every 1 mole of O2 there are 2 moles of H2. So we also have 2 X .003 moles or .006 Moles of H2

4. Convert moles to volume.

One mole of any gas has a volume of 22.4 liters at STP. Charles law states that the quantity volume (V) is directly proportional to the temperature (T)

represented by the equation V1/T1=V2/T2

So if you have a generator that is operating for 1 minute at 74F degree 56.22C drawing 20 amps @ 1.24 Volts. A Hydrogen Generator should produce:

V2=V1/T1X T2 = (56.22+273) (.009326) (22.4)/273 = .2529 liters of gas

Note: Systems operating at or above 100 C need to subtract out the partial vapor that is being co-generated as steam.

5. Adjust for operating volts:

If you have a hydrogen generator running off your alternator of your car at 13.8 Volts (and not 1.24Volts) then you should adjust by a fractional factorial:

13.8/1.24= 11.24

So you should expect 11.24 X .2519=2.8 lpm

6. To determine the efficiency of your generator

Take the actual liters divided by the theoretical liters X 100 to get efficiency.

Below is provided a calculator for making this determination:

Faraday's Calculation.