Hydrogen is the most abundant element in the universe. As a secondary energy, hydrogen energy is the best carbon-neutral energy carrier, which can be used as fuel for power generation, heating and transportation. It has the advantages of zero pollution, high calorific value, storability, sufficient reserves and wide application. The energy storage characteristics of hydrogen make it have the potential of flexible application across time and space, which can effectively connect with renewable energy and contribute to the consumption and larger-scale development of renewable energy. Based on the advantages and potential of hydrogen, in the context of coping with climate change and global energy transformation, it is generally believed that hydrogen energy will become the key node of the future energy system and play a key role in global energy transformation and improving the flexibility of the energy system. In recent years, global capital, technology, public opinion and other factors are giving birth to this round of hydrogen energy boom.
1 development status of hydrogen energy industry
This hydrogen energy boom began in developed countries in Europe, America and Japan and gradually spread to the whole world. The European Union, the United States and Japan have incorporated hydrogen energy into their national energy development strategies, and issued industrial development plans and supporting policies. The United States attaches importance to the cultivation of key technologies in the hydrogen energy industry chain, and has absolute advantages in the application of fixed fuel cell power generation, hydrogen fuel cell forklifts and automobiles. The EU has achieved zero emissions, and hydrogen energy is an important starting point. Germany has formulated a national hydrogen energy strategy to support the development of hydrogen production from renewable energy, hydrogen-based synthetic fuel and fuel cell industries and technologies. Japan and South Korea have issued detailed development roadmaps with clear policy guidance, and they are in a leading position in the development of fuel cell vehicles, household fuel cells, hydrogen station networks and hydrogen technology. The report "Hydrogen Scale Expansion" issued by the International Council for Hydrogen Energy predicts that hydrogen energy will account for about 18% of global energy demand in 2050, and heating and power supply in industry, transportation and construction will be the key areas of hydrogen energy application.
In China, hydrogen energy is positioned as a strategic energy technology, and the favorable policies are gradually released. In 20 19, hydrogen energy was written into the government work report for the first time. In 2020, People's Republic of China (PRC) Energy Law (Draft for Comment) listed hydrogen energy as an energy category for the first time. In the same year, hydrogen energy was included in the annual national economic and social development plan, and the demonstration and promotion of fuel cell vehicles and the preparation of the National Strategic Plan for the Development of Hydrogen Energy Industry were initiated. At the national level, continuous policy support is given to the hydrogen energy industry in terms of legislation, top-level design, demonstration and application, and the healthy and sustainable development of the hydrogen energy industry is planned, guided and standardized as a whole. Under the continuous and stable policy environment, with the superimposed catalysis of social capital, relevant enterprises in the upstream and downstream of the industrial chain and local governments, the domestic hydrogen energy infrastructure represented by hydrogen refueling stations (table 1) and key technologies and equipment in the manufacturing-storage-transportation-use industrial chain have been developed in recent years, and hydrogen energy industry hotspots such as the Pearl River Delta, the Yangtze River Delta and Beijing-Tianjin-Hebei have taken shape. At present, the whole industry is in the stage of technical research and demonstration application. According to public information, there are currently more than 6,000 hydrogen-fueled vehicles in China, and 46 hydrogen refueling stations are operating. The White Paper on Hydrogen Energy and Fuel Cell Industry in China (20 19) predicts that in 2035, hydrogen energy will account for 5.9% of the total domestic terminal energy, with 0/500 hydrogen refueling stations and 0/300 fuel cell vehicles.
Faced with the global climate change policy, European oil companies such as Shell, Total and BP have put forward the goal of "net zero carbon emission" in 2050, betting that green low-carbon energy has become a universal choice, among which the layout of green hydrogen production plants, hydrogen refueling stations and other hydrogen energy businesses is the key direction. Up to now, Shell's hydrogen energy business has invested in more than 24 hydrogen refueling stations in the United States, Japan and Germany, and cooperated with Total and other enterprises to accelerate the H2 mobility project in Germany (it is estimated that the construction scale of hydrogen refueling stations will exceed 400). Domestic petrochemical enterprises have the advantages of hydrogen source and sales network in the development of hydrogen energy. China Petrochemical Company has planned and built a network of hydrogen production, hydrogenation stations and storage and transportation facilities. 20 18 China Petrochemical joined the International Commission on Hydrogen Energy, and 20 19 cooperated with Air France in hydrogen energy, adopting a new mode of "integration of oil, hydrogen and electricity" and equipping hydrogen stations on the basis of existing gas stations. It has been built in Guangdong and Guangdong.
2 industrial chain technology and cost bottleneck analysis
Countries around the world have made remarkable progress in the demonstration and application of hydrogen energy and hydrogen fuel cell vehicles, but the hydrogen energy industry involves many links such as production, storage, transportation and use, with long industrial chain and complex technology. In reality, the large-scale popularization and application of hydrogen energy still faces the bottleneck of high manufacturing cost of hydrogen fuel cells, weak facilities of hydrogen refueling stations and high terminal hydrogen cost.
2. 1 Technical factors lead to high manufacturing cost of hydrogen fuel cells.
Hydrogen fuel cell system consists of stack, gas supply system and control system. The fuel cell stack is the core component that converts chemical energy into electrical energy, and the cost of the fuel cell stack accounts for about 60% of the total cost of the hydrogen fuel cell system (see figure 1). The main factors causing the high cost of the stack include: membrane electrode, the manufacturing process of the stack and the requirements of the use environment. The bottleneck of stack technology also leads to the high cost of hydrogen fuel cell system.
Membrane electrode is the core component of the stack, which consists of catalyst, proton exchange membrane and carbon paper, and its cost accounts for about 36% of the hydrogen fuel cell system. At present, the commercial catalyst is platinum/carbon, which accounts for about 23% of the cost of hydrogen fuel cell system and is the main source of cost. The cost of proton exchange membrane and carbon paper materials is also high, and they are mainly imported at home, so there is still a gap between performance and mass production. Membrane electrode has developed to the third generation of ordered membrane electrode technology, and the trend is to reduce the mass transfer resistance at high current density, further improve the performance of fuel cells, reduce the amount of catalyst and greatly reduce the material cost of membrane electrodes.
Uniformity is an important factor restricting the performance of the stack, and it is also the key to affect the manufacturing cost. The stack is usually composed of hundreds of single cells connected in series, and its uniformity is related to the uniformity of materials and the uniformity of parts manufacturing process. In particular, the uniformity of fluid distribution is not only related to materials, components and structures, but also closely related to the assembly process and operation process of the stack. Due to the non-uniformity caused by the accumulation of water during operation and the non-uniformity caused by the edge effect of the stack, the non-uniformity of one or several batteries in the stack will lead to low local battery voltage and limit the load amplitude of current. The non-uniformity in design, manufacture, assembly and operation control directly affects the specific power of the stack, and then affects the cost of the stack.
2.2 The high cost of hydrogen fuel cell vehicles limits the scale of commercial sales.
The high cost of vehicle fuel cell system is the main reason for the high price of hydrogen fuel cell vehicles. The fuel cell system, which consists of main components such as stack, hydrogen bottle and air compressor, is the core of hydrogen fuel cell vehicle, accounting for about 50% of the cost of hydrogen fuel cell vehicle. In addition to the high cost of stack, the cost of hydrogen supply system and gas supply system is also high, and there is still a big gap in technology with foreign countries.
Hydrogen fuel cell vehicles have not been produced on a large scale, and the market sales are limited. At present, Toyota, the world's largest hydrogen fuel cell vehicle company, has an existing production capacity of only 3,000 vehicles per year, and it will reach 30,000 vehicles per year in 2020. Although Honda, Hyundai, Nissan and SAIC have successively launched commercial vehicles, their market sales are still limited (see Table 2). Yihuatong, a hydrogen fuel cell engine enterprise, cooperated with Yutong Bus, Foton Motor and Zhongtong Bus to build the first fully automatic hydrogen fuel cell engine production line in China, with an annual production capacity of only 1 10,000 units. Small production scale leads to higher vehicle cost. For example, the price of Toyota official website 2020 Mirai is $58,550, which is 2.5 times that of the hybrid 2020 Prius ($24,325), far higher than consumers' expectations.
2.3 The lack of filling vehicles and the localization of equipment are still the main limiting factors for the development of early hydrogen refueling stations.
The construction and operation of hydrogen refueling stations are still facing difficulties in the early stage of development. It is very difficult to build a new gas station and transform the existing gas station into a gas station. GB 505 16—20 10 "Technical Specification for Hydrogen Stations" is the main construction standard for new hydrogen stations, which requires high safety of hydrogen storage, transportation and site selection conditions, especially the fire distance between hydrogen process facilities and buildings and structures outside the hydrogen station. The design of refueling station should comply with GB 50 156 Code for Design and Construction of Automobile Refueling and Filling Station. It is difficult to rebuild the existing gas station facilities, especially in big cities and densely populated areas.
The network layout of hydrogen refueling stations and the market scale of hydrogen fuel cell vehicles are still mutually restrictive factors in the early stage of the industry. The promotion of pure electric vehicles and the construction of charging piles are also facing the same problem. There are fewer charging vehicles, which limits the benign rolling development of hydrogen refueling stations. At present, there are 66 hydrogen refueling stations under construction and 46 in operation in China, which are distributed in 19 provinces and cities, among which Guangdong, Shanghai, Jiangsu and Shandong are the main concentration areas of hydrogen refueling stations (see table 3). At present, there is still a big gap between the number of domestic hydrogen refueling stations and the planned construction of 100 in 2020 and 1000 in 2030. Shanghai Anting and Beijing Yongfeng Hydrogenation Station, the earliest demonstration operations in China, have been in an embarrassing situation with few hydrogenation vehicles. There are also few vehicles in the completed hydrogen refueling stations of German H2 mobility project, but the goal of building a network of 400 hydrogen refueling stations in 2023 is still being promoted, trying to solve the problems in the early stage of the industry.
The localization of hydrogen refueling station equipment is still facing bottlenecks, and key equipment such as hydrogen compressors and filling machines are still mainly imported. According to public information, the construction cost of a 35MPa hydrogen refueling station with a filling capacity of 1000kg/d is as high as150,000 yuan, which is several times higher than that of a gas station. Among them, hydrogen storage device, compressor, filling machine, station control system, etc. It accounts for about 60% of the total investment of hydrogen refueling stations, of which hydrogen compressors account for the highest proportion, about 30%.
2.4 The cost of terminal hydrogen is high, and the key technologies of production, storage and transportation need to be broken.
At present, the price of hydrogen as fuel is still much higher than that of fossil fuels. The hydrogen consumption cost of hydrogen fuel cell vehicles includes the whole process cost from preparation, storage, transportation and filling. Compared with traditional fuel vehicles, the fuel consumption of hydrogen fuel cell vehicles is higher than that of fuel vehicles. According to the operation experience of domestic demonstration projects, the fuel cost of hydrogen fuel cell vehicles is about 1.8 times that of fuel vehicles. Although the terminal price of hydrogen fuel is higher than that of fossil fuel, domestic and foreign subsidies are still used to make up for the price disadvantage of hydrogen fuel and promote the development of hydrogen fuel cell automobile industry.
Hydrogen production from fossil energy has mature technology, large scale and low cost (see Table 4). The existing domestic industrial hydrogen production capacity is 25 million t/a, and the main sources of hydrogen are coal hydrogen production, natural gas hydrogen production, petroleum hydrogen production, industrial by-product hydrogen production and electrolytic water hydrogen production, accounting for 40%, 12%, 12%, 32% and 4% respectively. In the early stage of the development of hydrogen energy and hydrogen fuel cell automobile industry, hydrogen production from fossil energy and industrial by-product hydrogen are the main sources of low-cost hydrogen fuel, which is conducive to promoting industrial development. However, the CO2 emission of hydrogen production from fossil energy is large, and the production of low-cost hydrogen from renewable energy is the direction and focus that the industry has been aiming at, and the ultimate goal is that the price of hydrogen is equal to that of fossil fuels.
Green and low-cost hydrogen production technology is the key to the development of hydrogen energy industry. Proton exchange membrane (PEM) water electrolysis hydrogen production technology is superior to alkaline water electrolysis hydrogen production technology in overall efficiency, working current density, hydrogen purity, gas production pressure and dynamic response speed (see Table 5 for details), which can adapt to the fluctuation of renewable energy power generation and is one of the key technologies for the development of hydrogen energy industry chain. However, at present, it faces the problem of high cost of hydrogen production due to the use of platinum catalyst and high power consumption. Breaking through key technologies such as platinum catalyst and electric reactor, further improving current density, system energy efficiency and reducing investment are the key development directions of PEM hydrogen production technology.
At present, the domestic standards and specifications for hydrogen storage and transportation are not perfect, which leads to the fact that hydrogen fuel can only be transported in gaseous state, which limits the technical choice of hydrogen refueling stations. Liquid hydrogen storage and transportation is only used in aerospace and military fields in China, and there is no standard and specification for liquid hydrogen supply in commercial hydrogen refueling stations. At the national level, hydrogen energy is managed as an energy source through legislation, and relevant standards for the production, storage, transportation and use of commercial liquid hydrogen are formulated. In 20 19, the third draft of the national standard for liquid hydrogen has been completed, which will fill the gap in the domestic civil liquid hydrogen standard, and may bring technological breakthroughs in the whole industrial chain of hydrogen energy, thus reducing the cost of terminal hydrogen use.
The density of liquid hydrogen is as high as 70.6g/L(-253). Under the same effective load, the storage and transportation capacity of liquid hydrogen is much higher than that of high-pressure hydrogen storage. Although the energy consumption of hydrogen liquefaction is more than 1 times higher than that of hydrogen compression, the transportation cost of liquid hydrogen is only 1/5~ 1/8 of that of high-pressure hydrogen. High-pressure hydrogen tube bundle truck is still the main mode of hydrogen transportation abroad, and its storage and transportation capacity is limited by gaseous hydrogen. See table 6 for details.
3 thinking and suggestions
Hydrogen energy and fuel cell industries have entered the early stage of demonstration and application, and large-scale commercialization still needs to solve the technical and cost bottlenecks of key links in the industrial chain. Specifically, accelerating the commercialization of hydrogen energy and fuel cell industry requires the concerted efforts of policies, planning, standards and specifications, technology and other factors.
Sustained and stable industrial support environment and corresponding industrial subsidies are very important for the development of early hydrogen energy industry. The state should start the top-level design of hydrogen energy and fuel cell industry as soon as possible, formulate the national industrial development strategic plan, formulate the industrial development implementation plan, coordinate the key development areas of hydrogen energy industry, and clarify the development path of industrial chain system, storage, transportation and use. In terms of technology, we will strengthen the key technologies and components of the industrial chain such as green and low-carbon hydrogen production, high-efficiency and low-cost fuel cells, hydrogen compressors and hydrogenation machines, accelerate the localization of equipment, and improve the standards and norms of the industrial chain. It is suggested that the state take the lead in setting up a major project of hydrogen energy science and technology, unite enterprises and scientific research institutes in universities, concentrate on breaking through core technologies, materials, equipment and key parts, build an ecological chain of independent technologies, materials and equipment, further reduce costs and promote the healthy and rapid development of the industry.
Looking forward to the future, breakthroughs in green hydrogen production, storage, transportation, filling and fuel cell technology, as well as the improvement and popularization of hydrogen energy infrastructure, will stimulate the diversified and large-scale application of hydrogen energy and fuel cell industry and promote hydrogen energy to play a more important role in global energy transformation.
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