The P41 electrolyzer

The P41 is a simple electrolyzer specifically designed to provide maximum output with the smallest footprint possible with off the shelf components. As with every part of this project, the important factors were ready availability of components at low cost, and ease of working with the components, so that anyone with average skills could build a device that would be comparable with commercial equipment. 

For this electrolyzer, the primary goal was to produce enough hydrogen to run a real time stationary fuel cell system within the smallest possible space without the gases intermingling. 

An important design consideration was to maximize the efficient use of energy input from renewable energy power sources. Most commercial electrolyzers are designed to run off utility power grids with a rectified DC source. The electrode materials used in these electrolyzers reflect that particular type and quality of power source. 

A minimum voltage of about 1.23 V at about 77°F will disassociate water into hydrogen and oxygen, but this process absorbs heat. At a voltage of about 1.49 at around 77°F, no heat is absorbed. Higher voltages than 1.49 

Experiments with a variety of materials led to the conclusion that monel is a perfect choice for electrodes in an electrolyzer designed for intermittent power supplies. It has an electrical resistance of about 42 micro ohms-cen-timeters at 20°C. This is much higher than, for instance, nickel, which has a resistance of 11. With higher resistance, more heat is generated as the current passes through the electrodes and electrolyte solution. 

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We did run a quick comparison test with another electrolyzer. This particular electrolyzer weighed in at about 30 pounds, used sintered nickel plates, and was about three times as large as our P41. The P41 weighs a little more than a pound and was less than half the size of the commercial electrolyzer. 

We connected the electrolyzers to matching solar panels and watched the results. The P41 began gassing immediately, whereas the commercial electrolyzer took about a half hour to release its contents into the feed tubes. This fact pointed out design flaws in the commercial electrolyzer. 

The P41 produced twice the gas that the commercial electrolyzer produced. We also noticed that the P41 performed extremely well under intermittent cloud cover as we had expected. Very sharp peaks and troughs in... 

Sharp peaks and troughs were evident in the other electrolyzer with minor atmospheric hindrances that vary from second to second and or minute to minute, such as moisture clouds or dust clouds. These are not perceptible to the naked eye, but never the less affect the power output of the PV panels and thus the gas production from the electrolyzer. Under these conditions, the P41 exhibited a rolling effect with a more consistent gas output, and with full cloud cover it was producing much more gas than the commercial electrolyzer. 

It is usually more cost effective and energy efficient to use larger electrolyzers, but this is not always the case. A larger electrolyzer can easily be built by simply scaling up the dimensions of the P41. 

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