High cost of hydrogen production become a limit
The World Hydrogen Energy Council proposed that by 2050, 20% of the carbon dioxide emission reduction in the global environment will be accomplished by hydrogen, and hydrogen energy will account for 18% of the final energy demand. According to the current global energy structure, non-polluting, high calorific value, and renewable hydrogen energy has become the most realistic choice.
At present, the main methods of hydrogen production are hydrogen production from chemical raw materials, hydrogen production from petrochemical resources, water and hydrogen production from electrolysis and other ways. The main raw materials used for hydrogen production from chemical raw materials are methanol, ethanol, liquid ammonia, etc., which have the advantages of high purity and low reaction requirements. Hydrogen production from petrochemical resources mainly uses petroleum, water gas, natural gas and other resources, which has scale effect and the raw materials are easy to obtain. The raw material used for hydrogen production by electrolysis of water is water, which is renewable and reliable. The whole process can be pollution-free if clean electricity is used. However, the process needs to consume a lot of electricity, so the cost is expensive. The reaction speed of hydrogen production from biomass energy is relatively slow and cannot meet the requirements of large-scale use.
From the perspective of hydrogen production process, different regions are suitable for different process according to resource differences. In areas rich in coal resources, it is more practical to use coal to produce hydrogen because of the low price of coal. At the same time, it is the most economical and environmentally-friendly method to obtain hydrogen energy by electrolysis of water due to the low electricity price in areas rich in wind power, photovoltaics, and hydropower. In areas without special resources, cost performance is the primary consideration when producing hydrogen.
Hydrogen production by electrolysis of water is one of the most widely used and mature methods at present. The hydrogen production process is the reverse process of hydrogen and oxygen combustion to generate water, so the water can be decomposed as long as the corresponding conditions are provided. The efficiency of providing electricity to split water to produce hydrogen is generally 75-85%. The process is simple and pollution-free, but consumes a lot of electricity, so its application is limited.
Cost reduction and efficiency improvement are the eternal theme. Cost is a topic that can never be avoided in commercial promotion. Taking hydrogen production by water electrolysis as an example, electricity costs account for about 75% of the cost of the entire hydrogen production process. To reduce the cost of hydrogen production, it is necessary to increase the utilization rate of electric energy.
By increasing the current density, the volume of the electrolytic cell can be saved, and its floor space is relatively saved in terms of large-scale investment. During transportation and installation, the weight of the electrolyzer is lighter, and it will have better advantages and convenience in transportation, lifting, installation and other aspects.
Hydrogen production from renewable energy has broad prospects. Solar energy is widely distributed, clean and pollution-free, and inexhaustible. Among them, the method of using photoelectric hydrogen production is called solar hydrogen energy system. With the improvement of energy conversion efficiency of solar cells, the reduction of cost and the extension of service life, the prospect of its use in hydrogen production is immeasurable.
At the same time, solar energy, wind energy and ocean energy can also produce hydrogen through electricity and use hydrogen as an intermediate energy carrier to regulate, store and convert energy, making the energy supply to users more flexible and convenient. The surplus electric energy can also be used to electrolyze water to produce hydrogen to storage energy if the power supply system with extra power at valley. With the gradual expansion of the application of hydrogen energy, the method of water electrolysis hydrogen production will be developed.