Research on The Evaluation of Technology Maturity in Multiple Scenarios for Hydrogen Fuel Cell

. Hydrogen, as an important clean energy source, is one of the key energy pathways for the future. Hydrogen fuel cells serve as the core carrier for the current terminal applications of hydrogen energy. Based on the S-curve evolution principle of the Inventive Problem Solving Theory, this paper establishes a technology maturity evaluation index system for the multi-scenario application of hydrogen fuel cells using the literature patent measurement method. A characteristic matrix for the evaluation index of technology maturity is designed, and the technology maturity of hydrogen fuel cells in two scenarios, namely transportation and building energy supply, in China is evaluated. The research results indicate that the application of hydrogen fuel cells in transportation scenarios in China is in the growth stage, while in building energy supply scenarios, it is still in the infancy stage. These findings contribute to accurately identifying the bottleneck stages of technology and market trends, thereby promoting the rapid development of fuel cell technology in China.


Background
The global energy industrial sector is focused on and committed to supporting clean energy usage and reducing or eliminating the emission of greenhouse gases by 2050.Hydrogen energy, as an important clean energy source, is one of the important energy routes in the future.Hydrogen fuel cell is a power generation device that uses hydrogen or hydrogen-rich gas as fuel to directly convert Chemical energy in the fuel into electrical energy through electrochemical reaction.It is the core carrier of current hydrogen energy terminal applications.At present, the commercial application of Hydrogen fuel cells is mainly concentrated in the Stationary power field [1] , transportation field [2] and portable charging field, and Hydrogen fuel cell vehicles are the mainstream development direction.However, there are still great obstacles in the commercialization of fuel cells.The life and economy of products are still far behind those of traditional energy technologies.The development of Hydrogen fuel cell industry depends on the progress of fuel cell technology [3] .Through the evaluation of Hydrogen fuel cell technology maturity in different application scenarios, it is conducive to accurately grasp the choke points of technology, scientifically formulate research and development plans and policy guidance, thus helping enterprises grasp market demand, scientifically select Technology roadmap, prevent low-level repetitive research, avoid unnecessary waste of scientific and technological resources, and has great significance in promoting the rapid development of fuel cell technology in China and commercialization of application scenarios.Technology maturity refers to the development status of a technology relative to a specific system or project, which reflects the degree to which the technology meets the expected goals of the project [4] .The earliest technology maturity concept was put forward by NASA in the 1990s [5] .The evaluation methods of technology maturity mainly include technology maturity level evaluation theory [6] , invention problem solving theory [7] , Product lifecycle theoretical innovation process model [8] , social network analysis method [9] , patent literature measurement method [10] , media exposure method [11] , etc.
In existing studies, technology maturity assessment methods mostly use a single indicator or a few rare indicators to determine the technical maturity of products.Due to the relatively single evaluation dimension reflected, the determination and grading evaluation of key technologies require extensive discussion and analysis by experts, which is very subjective.In addition, there are many types of Hydrogen fuel cells, and the composition of the cells involves very complex process materials, and the types of cells are different in different scenarios.Therefore, in this paper, we construct a multi-dimensional technology maturity evaluation index system for hydrogen fuel cells based on the theory of invention problem solving and patent Bibliometrics, to evaluate the technology maturity of Hydrogen fuel cells in different application scenarios.

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Method and data

Theoretical basis
The Theory of Inventive Problem Solving (TRIZ) was proposed by Professor G.S. Altshuller of the former Soviet Union.The S-type evolution law of technological systems is the first of the eight laws of TRIZ theory [12] .The evolution process of any technological system develops in a more advanced direction over time, and their evolution processes have similar patterns, going through four stages: infant, growth, mature and decline.These four stages constitute a "Technology life cycle" of the product, and its law is similar to an S-shaped curve [13] .It reveals the whole process of a new product from birth to death from its Technology life cycle.The theory judges the technological maturity of the product by tracking and analyzing the technical performance, number of patents, patent level and profitability indicators of the product, so as to locate the stage of technological evolution of the product.Products in their infancy have a lot of originality and high patent level, but they require a lot of manpower and financial investment, and also bear great technical risks; Products in the growth stage focus on appearance and practicality, with good profits.The number of enterprises gradually increases, and market competition is beginning to emerge; Products in the maturity stage have seen a significant increase in the number of enterprises, achieving optimal profits, and fierce market competition; Products in the later stage of maturity or decline may experience price wars, with production concentrated in larger enterprises and the number of enterprises gradually decreasing [14,15] .

Application scenario oriented multidimensional technology maturity evaluation index of Hydrogen fuel cell
The basic data of this paper includes paper data, patent statistics data, enterprise data, and mainstream media data.Build a multi-dimensional technology maturity evaluation index system that includes indicators such as patent growth rate, number of patent holders, proportion of invention patents, technological competitiveness, and media exposure in application scenarios.The calculation method of each indicator in the system are shown in the table below.In the evaluation index system, the growth rate of patents and the growth rate of patent holders are used to characterize the technological development speed and the scale of collective advancement of hydrogen fuel cells.The proportion of invention patents is used to reflect the degree of application conversion of hydrogen fuel cell technology.The technology competitiveness index reflects the level of patent technology in China.The proportion of engineering application literature and conference literature reflects the level of discussion and application of hydrogen fuel cell technology in the scientific community.The growth rate of competing companies reflects the market judgment of capital in the industry.The annual media exposure index of application scenarios reflects the practical application of hydrogen fuel cell technology.

Data sources
This paper uses patent data from the patent database of the China National Intellectual Property Administration, literature data from the web of science, Engineering Village and CNKI, enterprise data from the AiQiCha Platform, and reports from microblog mainstream media accounts as analysis samples.The sampling period is 22 years, from January 1, 2000 to December 31, 2022.The key word of patent database is "fuel cell", the key word of web of science database, Engineering Village and CNKI is "Proton exchange membrane fuel cell or solid oxide fuel cell", the key word of AiQiCha Platform through supplier search is "Hydrogen fuel battery", and the key word of microblog is "Hydrogen fuel cell" and "hydrogen energy utilization".A total of 62632 patent information, 120219 foreign language paper data, 7128 Chinese literature data, 898 enterprise data, and 43466 media report data were retrieved.

Multi scenario technology maturity evaluation of Hydrogen fuel cell
Using the calculation formula in Table 1, we can calculate the development trend of other indicators such as patent growth rate and patentee growth rate over the past 20 years.
Figure 1 to Figure 6 shows the calculation results of various indicators and the variation curve of indicator values over time from 2001 to 2022.Comparing the change curve of each index value with time, determine the position of the technology maturity evaluation index in the feature matrix.Figure 7 and Figure 8 shows the calculation results of the technology maturity evaluation index matrix.It can be seen that the number of patents, the number of patentees, the proportion of invention patents, technical competitiveness, the proportion of engineering application literature, and the proportion of conference contributions of Hydrogen fuel cells fall within the growth period, and the number of competitive companies has entered the mature period, The media exposure of transportation vehicle application scenarios is also in the growth range, while the media exposure of building energy supply application scenarios is in the infant period.

Conclusion
In this paper, the technical maturity evaluation index system of multi scenario application of Hydrogen fuel cells is established through the literature patent measurement method.Based on the S-shaped curve evolution rule of the invention problem solving theory, the technical maturity evaluation index characteristic matrix is designed to evaluate the technical maturity of China's Hydrogen fuel cell transportation and building energy supply scenarios.The calculation results show that China's Hydrogen fuel cell application scenario in transportation vehicles has entered a growth period, and the application scenario in building energy supply is still in infancy.According to the development trend of the whole life cycle of Hydrogen fuel cell technology, the transportation landscape of Hydrogen fuel cells will quickly enter a mature period.

Fig. 1
Fig. 1 Trend of changes in the number of authorized patents and patent growth rate

Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6
Fig. 2 Trend of changes in the number of patentees and the growth rate of patentees

Fig. 8
Fig.8 Technology maturity evaluation index matrix result of building energy supply application scenario

Table 1 .
Hydrogen fuel cell technology maturity evaluation in- (total number of patents in year ttotal number of patents in year t-1)/ total number of patents in year t-1

Table 2 .
Characteristic matrix of technical maturity evaluation indicators