At present, there are three conventional hydrogen production methods: one is using fossil energy such as coal and natural gas to produce hydrogen; Second, hydrogen is produced from industrial by-product gas; The third is electrolysis of water to produce hydrogen. In the world, natural gas is mainly used to produce hydrogen. In China, due to the rich coal resources, the technical route of hydrogen production from coal is mainly adopted.

Electrolytic water hydrogen production technology has very good advantages: first, it does not use fossil fuels, does not produce harmful gases; Second, the product gas purity is high, usually above 99.7%; Third, the process and equipment are simple; Fourth, high level of automation, microcomputer control, stable and reliable operation. However, there is still a gap between domestic hydrogen production technology and foreign technology, such as high cost of hydrogen production by water electrolysis, insufficient durability and reliability of electrolytic cell, relatively low efficiency of electrolytic cell. At present, China's electrolytic water hydrogen production accounted for only 1%-3%. However, with the development of hydrogen production from water electrolysis, the production cost per unit of hydrogen decreases gradually. We expect that electrolysis of water to produce hydrogen will be the mainstream of the future.

Although coal gasification and hydrogen production from natural gas can be profitable, large-scale hydrogen production can be achieved in China. However, these two methods of hydrogen production require non-renewable resources and are not sustainable. In addition, the carbon emissions of these two methods are very high. The carbon dioxide emissions of hydrogen production from coal gasification are as high as 193kg/GJ, and the carbon dioxide emissions of hydrogen production from natural gas are as high as 69 kg/GJ, which is not conducive to environmental protection. However, the carbon dioxide emissions from electrolysis of water to produce hydrogen do not exceed 30 kg /GJ, with low environmental pollution and sustainability.

It can be said that hydrogen production by electrolysis of water belongs to a clean and sustainable way of hydrogen production and is an important direction of hydrogen production in the future.

At present, the cost of electrolytic water hydrogen production mainly comes from fixed asset investment, power cost and fixed production and operation cost, among which the electricity price accounts for 77% of the total cost. The high electricity price is the main reason for the high cost of electrolytic water. In order to promote the development of electrolysis of water to produce hydrogen, it is necessary to reduce the price of electricity. In addition, it is necessary to improve the efficiency of hydrogen production from electrolytic water and reduce the cost of large-scale hydrogen production. Effective use of renewable energy including hydro, tidal, solar and wind power. China is rich in hydropower resources, generating nearly 300 billion KWH of electricity per year. However, hydroelectric power generation needs water-rich equipment and peak regulation, which will produce a large amount of waste water energy, resulting in a great waste. China's available wind energy is huge, equivalent to two-thirds of its water resources.