Hydrogen is widely distributed in nature, and only a very small amount of free hydrogen exists in the natural state. Industrial hydrogen refers to the combustible gaseous hydrogen product produced on a large scale from industrial raw materials by certain means. This process of extracting industrial hydrogen from hydrogen-containing raw materials through energy input is called artificial hydrogen production, including fossil fuel hydrogen production, water decomposition hydrogen production, biotechnology hydrogen production and solar hydrogen production. Hydrogen energy, as the chemical energy of hydrogen, is manifested as energy released during physical and chemical changes. It is an important type of energy with secondary energy properties. This large-scale artificial hydrogen production and utilization of hydrogen energy is called the hydrogen industry, including upstream hydrogen production, midstream storage and transportation, and downstream applications. The various industrial sectors in the hydrogen industry system are based on certain technical and economic connections, namely the hydrogen industry industry chain, including the hydrogen industry value chain, hydrogen industry enterprise chain, hydrogen industry supply and demand chain and hydrogen industry space chain.
1 The global hydrogen industry has begun to take shape
The global hydrogen industry has developed rapidly, with the market size growing from US$187.082 billion in 2011 to US$251.493 billion today, with a growth rate of 34.4%. Among them, the United States is the largest importer of industrial hydrogen, with a total import value of US$248 million, while the Netherlands is the largest exporter of industrial hydrogen, with an annual total export value of US$342 million.
Human society has experienced three industrial revolutions. Since the middle of this century, along with the fourth industrial revolution, the global transition to new energy has begun. Looking at the history of energy development, the upgrading of the three major energy sources reflects the "three major economic" forms.
Watt's invention of the steam engine prompted the first major conversion of firewood to coal, which manifested as a "high-carbon economy";
Daimler invented the internal combustion engine, completing the second major conversion of coal to oil and gas, rendering a "low-carbon economy";
Modern scientific and technological progress and today's environmental protection requirements have promoted the third major conversion of traditional fossil energy to non-fossil new energy such as hydrogen energy. The world may gradually enter the non-carbon "hydrogen energy era"
2 Artificial hydrogen production mainly relies on fossil resources
The global industrial hydrogen market has a strong regionality and has formed three major regional maps of Asia-Pacific, North America and Europe.
Fossil resources are currently the main raw materials for hydrogen production, among which coal gasification hydrogen production has great development potential.
2.1 Industrial hydrogen production is regional
The Asia-Pacific region ranks first in the world in industrial hydrogen production, followed by North America.
The rapid economic growth of developing countries in the Asia-Pacific region, such as China and India, has brought about strong demand for clean energy such as hydrogen in the Asia-Pacific region.
China's demand and production of industrial hydrogen are strong and are increasing year by year. At present, it maintains a state of supply and demand balance, and both demand and production rank first in the world.
As a major country in the use of hydrogen energy in the world, China has maintained the world's first place for many years since its production exceeded 1 000×10 4 t for the first time in 2009.
2.2 Hydrogen production from fossil resources is dominant
At present, the raw materials for artificial hydrogen production are mainly fossil resources such as petroleum, natural gas, and coal. Compared with other hydrogen production methods, the fossil resource hydrogen production process is mature and the raw material price is relatively low, but it will emit a large amount of greenhouse gases and pollute the environment.
Previously, more than 96% of the world's main raw materials for artificial hydrogen production came from thermochemical reforming of traditional fossil resources, and only about 4% came from electrolysis of water. Coal and natural gas are the main raw materials for artificial hydrogen production in my country, accounting for 62% and 19% respectively. Hydrogen production by water electrolysis occupies a special position in Japan's hydrogen industry, and its salt water electrolysis hydrogen production capacity accounts for 63% of the country's total artificial hydrogen production capacity.
2.3 Coal gasification hydrogen production has great development potential
Coal gasification refers to the reaction of coal with a gasifying agent under high temperature, normal pressure or pressurized conditions to form a gas product. With the development of coal-to-syngas and coal-to-oil industries, the output of coal-to-hydrogen production has increased year by year, with a large scale and low cost, and the cost of hydrogen production is about 20 yuan/kg. In addition, in the production process of chemical products (including synthetic ammonia, methanol, etc.), the devices for recovering industrial hydrogen with a purity greater than 99% from hydrogen-containing relaxation gas are becoming more mature and increasing.
Underground coal gasification hydrogen production has great development potential and is also an effective way to transform and utilize coal in a clean manner. Underground coal gasification hydrogen production technology has the advantages of high resource utilization and less damage to the surface environment. It conforms to the resource structure characteristics of my country's rich coal but insufficient oil and gas. However, this technology is still in the exploratory stage and is still a long way from commercial utilization.
3 Efficient hydrogen storage and transportation technology is the focus of development
Safe and efficient hydrogen storage and transportation technology is the key to realizing the practical application of hydrogen energy. The storage methods of hydrogen energy mainly include low-temperature liquid hydrogen storage, high-pressure gaseous hydrogen storage, solid hydrogen storage and organic liquid hydrogen storage. Different hydrogen storage methods have different hydrogen storage densities, among which the gaseous hydrogen storage method has the smallest hydrogen storage density and the metal hydride hydrogen storage method has the largest hydrogen storage density.
3.1 The cost of low-temperature liquid hydrogen storage is high
The large-scale and cheap production and storage and transportation of industrial hydrogen are the basis for realizing the practical use of hydrogen energy. Gaseous hydrogen is liquid at -253°C, and the density of liquid hydrogen is 845 times that of gaseous hydrogen. The weight ratio of liquid hydrogen storage is between 5.0% and 7.5%, and the volume capacity is about 0.04 kgH 2 /L. Hydrogen liquefaction is expensive and consumes a lot of energy (4 ~ 10 kWh/kg), accounting for about one-third of the cost of liquid hydrogen production. Liquid hydrogen storage containers need to have extremely high insulation capacity to avoid boiling and vaporization of liquid hydrogen.
At present, liquid hydrogen is mainly used as a fuel for space rocket propulsion, and its storage tanks and trailers have been used in my country's aerospace and other fields. With the development of human space programs, liquid hydrogen storage containers are becoming larger, and large liquid hydrogen insulated storage tanks with a storage capacity of more than 1,000 m3 can be built.
3.2 High-pressure gaseous hydrogen storage technology is mature
High-pressure gaseous hydrogen storage is currently the most commonly used and most mature hydrogen storage technology. Its storage method is to compress industrial hydrogen into a high-pressure resistant container. High-pressure gaseous hydrogen storage devices mainly include fixed hydrogen storage tanks, long-tube gas cylinders, long-tube bundles, steel cylinder groups, and vehicle-mounted hydrogen storage cylinders.
Steel cylinders are the most commonly used high-pressure gaseous hydrogen storage containers, which have the advantages of simple structure, low energy consumption for compressed hydrogen preparation, fast filling and discharge speed, but also have the disadvantages of poor safety performance and low volume capacity. At present, the hydrogen refueling stations that have been built and are under construction in China generally use long-tube gas cylinder group hydrogen storage equipment.
3.3 Solid-state hydrogen storage technology is not yet mature
Solid-state hydrogen storage is the most promising hydrogen storage method, which can effectively overcome the shortcomings of high-pressure gaseous and low-temperature liquid hydrogen storage methods. It has the advantages of high hydrogen storage volume density, easy operation, convenient transportation, low cost, high safety, etc. It is suitable for occasions with strict volume requirements, such as hydrogen fuel cell vehicles. Solid-state hydrogen storage technology can be divided into physical adsorption hydrogen storage and chemical hydride hydrogen storage. The former can be subdivided into metal organic frameworks (MOFs) and nanostructured carbon materials; the latter can be subdivided into metal hydrides such as titanium, magnesium, zirconium and rare earth, as well as non-metallic hydrides such as borohydrides and organic hydrides.
Metal hydride hydrogen storage has the advantages of high hydrogen storage density, high purity, high reliability (no high pressure or low temperature conditions are required) and simple hydrogen storage process. The main principle is to select suitable metal hydrides and combine hydrogen with another substance (hydrogen storage alloy) under low pressure conditions to form a quasi-compound state. At present, metal hydride hydrogen storage is still in the research stage and has not yet been commercialized. It is mainly restricted by the following factors: (1) Hydrogen storage alloys are expensive; (2) The structure is complex. Since a large amount of heat is released during the hydrogen storage process, heat exchange equipment must be added to the storage device; (3) The hydride itself has poor stability and is prone to form harmful impurity components. After repeated use, the performance is significantly reduced; (4) The hydrogen storage quality is relatively low. If measured by mass, it can only store 2% to 4% of industrial hydrogen.
3.4 Organic liquid hydrogen storage has attracted much attention
Organic liquid hydrogen storage technology achieves hydrogen storage through the reversible hydrogenation and dehydrogenation reactions of unsaturated liquid organic matter. This hydrogen storage method has the advantages of high quality, high volume hydrogen storage density, safety, easy long-distance transportation, and long-term storage. Organic liquid hydrogen storage technology is still in the research and development stage, and still has disadvantages such as demanding technical requirements, high cost, low dehydrogenation efficiency, and easy coking and deactivation.
The equipment cost of catalytic hydrogenation and dehydrogenation devices is high. The dehydrogenation reaction needs to be completed under low-pressure and high-temperature heterogeneous conditions. Limited by heat and mass transfer and reaction equilibrium limits, the dehydrogenation reaction efficiency is low and side reactions are prone to occur, resulting in impure hydrogen products. In addition, under high temperature conditions, the pore structure of the dehydrogenation catalyst is easily destroyed, resulting in coking and deactivation.
4 Hydrogen industry infrastructure
The main mode of industrial hydrogen transportation is pipeline transportation of high-pressure gaseous or liquid hydrogen. Long-distance pipelines need to carry out basic research on the compatibility of pipeline steel and high-pressure hydrogen, and innovate pipeline operation and management methods to achieve long-distance, high-pressure, large-scale hydrogen pipeline construction.
4.1 Pipeline hydrogen transportation is in the initial stage
Pipeline hydrogen blending and hydrogen-oil co-transportation technology are important links in achieving long-distance and large-scale hydrogen transportation. Global pipeline hydrogen transportation started early, but developed slowly. Europe has been transporting hydrogen by long-distance pipeline for more than 80 years. It currently has a total length of about 1,500 km of hydrogen pipelines, of which the France-Belgium hydrogen pipeline with a length of nearly 400 km is the longest in the world. The length of the existing hydrogen pipeline in the United States is 720 km, which is much shorter than the length of its natural gas pipeline (nearly 55×10 4 km).
Our country already has many hydrogen pipelines in operation, such as the Sinopec Luoyang Refining and Chemical Jiyuan-Luoyang hydrogen pipeline with a total length of 25 km and an annual gas transmission capacity of 10.04×10 4 t; the Wuhai-Yinchuan coke oven gas pipeline has a total length of 216.4 km and an annual gas transmission capacity of 16.1×10 8 m 3, which is mainly used to transport coke oven gas and hydrogen mixed gas.
4.2 Hydrogen-oil joint construction of hydrogen refueling stations
With the continuous expansion of the hydrogen industry market, the hydrogen industry industry chain is tending to be continuously improved. At present, hydrogen fuel vehicles are developing rapidly, the demand for industrial hydrogen has increased greatly, and the construction of hydrogen refueling stations has also accelerated accordingly.
As of the end of 2017, there were 328 hydrogen refueling stations in operation worldwide, including 139 in Europe, 119 in Asia, 68 in North America, and 1 in South America and Australia.
The "Blue Book on the Development of China's Hydrogen Energy Industry Infrastructure" has made plans for the development goals of my country's medium- and long-term hydrogen refueling station construction and fuel cell vehicles. It is expected that my country will build 100 hydrogen refueling stations and 1,000 by 2030. As of February 2018, China has built and is building a total of 31 hydrogen refueling stations, of which 12 are in operation.
The main facilities of a hydrogen refueling station include hydrogen storage devices, compression equipment, filling equipment and station control systems. At present, the global average construction cost of a hydrogen refueling station is between 2 million and 5 million US dollars, of which the compressor cost is the highest, accounting for about 30% of the total cost. The construction cost of hydrogen refueling stations in China is relatively low, ranging from 2 million to 2.5 million US dollars (35 MPa hydrogenation capacity). Therefore, it is necessary to accelerate the localization process of industrial hydrogen compressors, reduce the construction cost of hydrogen refueling stations, and promote the development of the hydrogen industry.
It is predicted that global hydrogen refueling stations will enter a rapid development stage, and there will be more than 1,000 stations in 2025. At the same time, the feasibility study of the joint construction of hydrogen refueling stations and gas stations will be increased, such as the joint construction model adopted by Germany, Japan and other countries, and the joint construction tests of multiple hydrogen refueling stations and gas stations carried out in Yunfu, Guangdong, China. In the future, it is very likely that a four-station joint construction model of hydrogen refueling stations, gas stations, gas stations, and charging stations will appear.
