Chengdu electrolytic water hydrogen production has the characteristics of green environmental protection, flexible production, high purity (up to 99.9% or more), and high value oxygen byproduct. Its unit energy consumption is about 4-5 kWh/cubic hydrogen, and the cost of hydrogen production is greatly affected by the electricity price, which accounts for more than 70% of the total cost. It is generally believed that when the electricity price is below 0.3 yuan/kilowatt hour, the cost of hydrogen production through electrolysis of water will be close to that of traditional fossil fuel hydrogen production.
Electrolysis of water for hydrogen production is a process in which water molecules are dissociated into hydrogen and oxygen through an electrochemical process under the action of direct current, and precipitated at the anode and cathode, respectively. At present, there are mainly alkaline water electrolysis tanks (AE) and proton exchange membrane water electrolysis tanks (PEM) for hydrogen production by electrolysis of water.
The chemical reaction formula for hydrogen production by electrolysis of water is as follows:
Cathode: 4H2O+4e -=2H2 ↑+4OH-
Anode: 4OH --4e --2H2O+O2 ↑
Total reaction formula: 2H2O=2H2 ↑+O2 ↑
1. Hydrogen production by electrolysis of water in alkaline liquid electrolyzers
Alkaline electrolytic cell technology is mature, with low production costs, a large range of gas production capacity, simple process, low cost, and easy maintenance. It is currently widely used. Usually, the working current density of alkaline liquid electrolyte electrolysis cells is about 0.25A/cm2, the energy efficiency is usually around 60% -70%, and the single machine gas production can reach 1000Nm3/h.

Chengdu Electrolytic Water Hydrogen Production Plant
Alkaline liquid water electrolysis technology uses KOH and NaOH aqueous solutions as electrolytes, and uses asbestos cloth, polyphenylene sulfide fiber membranes, etc. as separators. Under the action of direct current, water is electrolyzed to generate hydrogen and oxygen. The produced gas needs to undergo dealkalization and mist treatment. Alkaline liquid water electrolysis achieved industrialization in the mid-20th century. This technology is relatively mature and has a service life of up to 15 years.
The alkaline liquid electrolyte electrolysis cell is difficult to quickly close or start, and the speed of hydrogen production is also difficult to quickly adjust. And it is necessary to maintain pressure balance on both sides of the anode and cathode of the electrolytic cell at all times to prevent hydrogen and oxygen gas from mixing through the porous asbestos film and causing explosions.
Therefore, it is difficult to combine alkaline liquid electrolysis tanks with renewable energy sources with fast fluctuation characteristics.

2. Proton exchange membrane (PEM) electrolysis of water for hydrogen production
PEM electrolysis uses proton exchange membranes instead of asbestos membranes to conduct protons and isolate gases on both sides of the electrode, avoiding the drawbacks of using strong alkaline liquid electrolytes in alkaline liquid electrolyte electrolysis cells.
The operating current density of PEM electrolysis cells is usually higher than 1A/cm2, at least four times that of alkaline water electrolysis cells, with high efficiency, high gas purity, green environmental protection, low energy consumption, no alkaline solution, small volume Advantages such as reliability and the ability to achieve higher gas production pressure. This technology has not yet been commercialized on a large scale in China, with a relatively small gas production per unit and a lifespan of less than 10000 hours.
The main components of a typical PEM electrolysis tank include anode and cathode plates, anode and cathode gas diffusion layers, anode and cathode catalytic layers, and proton exchange membranes. Compared with alkaline water electrolysis, PEM water electrolysis system does not require dealkalization and has greater pressure regulation margin. In the early stages of commercialization, the cost of PEM was mainly concentrated in the PEM electrolysis cell itself. Improving the operating current density can reduce the investment in electrolysis equipment. Moreover, a wide range of operating current density is more conducive to matching the volatility of renewable energy. It is considered a promising water electrolysis technology at present.