Comprehensive Evaluation of Hydrogen Production from Coal Base on AHP& GRA-TOPSIS

Coal is the cornerstone of China's energy. However, with the proposed goal 1 of carbon peak and carbon neutral in China, coal enterprises are in urgent need of 2 exploring the path of transformation and development. Coal to hydrogen is an important 3 way to achieve sustainable development of the coal industry.In this paper, four 4 hydrogen production technologies, including coal gasification, coke oven gas, 5 electrolytic water and solar energy, are studied.A comprehensive evaluation model 6 based on GRA-TOPSIS was constructed.Four kinds of hydrogen production 7 technologies are evaluated and analyzed.The research shows that the coke oven gas is 8 the most suitable hydrogen production technology for the transformation and 9 development of coal enterprises.The evaluation model of hydrogen production 10 technology in the transformation and development of coal enterprises constructed in 11 this paper has a certain guiding effect on the technology selection of coal enterprises in 12 the development of hydrogen industry 13

the development of the hydrogen energy field in China has accelerated into the 1 industrialization stage. 2 Meanwhile, China is rich in coal resources, and hydrogen production from coal is 3 the main form of hydrogen production in China (Yan, 2019), which can significantly 4 increase the added value of coal products (Chen et al. 2019). 5 However, hydrogen production technology is complex, and the transformation and 6 development of energy enterprises often require comprehensive consideration from 7 multiple aspects.Therefore, a comprehensive evaluation system model based on energy, 8 economy, environment, technology and society has been established based on the 9 comprehensive study of hydrogen technology selection of various hydrogen production 10 technologies.In view of the mainstream mature hydrogen production technology and 11 the consideration of renewable energy utilization, four hydrogen production 12 technologies including coal gasification hydrogen production, coke oven gas hydrogen 13 production, water electrolysis hydrogen production and solar energy hydrogen 14 production were selected for comprehensive evaluation, in order to obtain the optimal 15 hydrogen production technology through hydrogen energy transformation and 16 upgrading of energy enterprises.It is of great significance to the transformation and 17 upgrading of coal industry and coal chemical industry which take hydrogen as the 18 breakthrough point. 19 2 Literature review 20 Technical economy is the internal driving force in the development of coal 21 industry transformation, there are many influence factors in technology economy, the 22 production methods, it is found that the hydrogen production technology from biomass 1 is the most efficient and environmental protection technology, which can not only 2 optimize the fuel structure and improve the air pollution status in China, but also reduce 3 the secondary pollution caused by the unreasonable utilization mode at present. Xie 4 Xinshuo (Xie et al., 2018) uses traditional hydrogen production technologies 5 (gasification hydrogen production, natural gas hydrogen production, etc.) and new 6 hydrogen production technologies (thermochemical hydrogen production, renewable 7 energy power generation hydrogen production, biomass gasification hydrogen 8 production, etc. ) as the object, the research on its life cycle assessment shows that wind 9 power hydrogen production technology has the best environmental protection, and 10 nuclear thermochemical hydrogen production has the potential for large-scale 11 application in the future.Niu Jiao (Niu, 2007) established an evaluation model based on 12 an improved fuzzy evaluation method. The hydrogen production technology with the 13 highest comprehensive benefit is natural gas steam reforming hydrogen production 14 technology, and the hydrogen production technology with the lowest comprehensive 15 benefit is hydrogen production by electrolysis of water. 16 The above research results are a single or multi-dimensional systematic evaluation 17 of various hydrogen-making technologies by experts and scholars, but the actual 18 application of hydrogen-making technology in a certain field has not been fully 19 considered. Under the current background of "carbon peak and carbon neutrality" and  Therefore, this article adds two dimensions of technology and society to the analysis of 3 the 3E model, that is, comprehensive analysis of each hydrogen production technology 4 from the five dimensions of energy, economy, environment, technology and society.

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And combined with a specific mining group for practical applications.

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(1) Resource applicability. Refers to the application of hydrogen technology, 21 whether the use of raw materials have special requirements, such as electrolytic water 1 hydrogen needs to contain electrolyte water, or coal hydrogenation furnace on the coal 2 moisture content, sulfur content, ash content and other requirements. The applicability 3 of various hydrogen production technology resources is divided into 5 grades according 4 to the most applicable, more applicable, less applicable, not applicable, as shown in 5   Table 1. The greater the resource suitability value, the better.   17 In the environmental impact of the main performance in the "three waste", that is,

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(1)Technical reliability. The reliability of technology means that the longer and 14 more complex the process of a technology during the production preparation phase, the 15 less reliable the technology will be. Therefore, the applicability of the four hydrogen 16 production technology resources is divided into 5 grades according to very reliable, 17 more reliable, more reliable, less reliable and unreliable. By qualitative analysis of the 18 length and complexity of the four hydrogen-making technology processes to determine 19 the reliability of each hydrogen-making technology, and give the corresponding value.

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The greater the value of resource suitability, the better. As shown in Table 1.

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(2)Purity of hydrogen production. The percentage by volume of hydrogen 22 produced by the four hydrogen production techniques prior to PSA. It reflects the 1 adaptability of hydrogen production technology to hydrogen energy terminal use. 2 (3)Proportion of scientific researchers. Refers to the proportion of researchers in 3 the hydrogen production technology system, which indirectly reflects the advanced 4 degree of the hydrogen production technology. Hydrogen production technology has 5 the characteristics of high professional requirements, both management and technical 6 work need a group of high-quality professional and technical personnel.   Table 2 11 (5)Technical maturity. Refers to the current development of hydrogen technology 12 at the current stage, but also an important basis for the selection of hydrogen technology.

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Generally divided into small test, pilot, industrial demonstration, industrial application 14 and commercialization. 15 Table 3 16 17 In this paper, the current strength of national policy support to reflect the country's 18 leading situation of hydrogen technology, that is, the applicability of policy. In addition, 19 for such a new energy society to its recognition is also an important indicator to measure 20 its social. However, due to the late start of hydrogen energy in China, hydrogenation 21 station, hydrogen vehicles, hydrogen technology and other nouns, the public contact relatively little, it is difficult to have a good understanding of it. Therefore, experts in 1 the field of hydrogen energy are selected as the recognition of hydrogen technology as 2 its social evaluation index.

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(1) The applicability of the policy. By studying China's national policies and 4 standards related to energy, environment and society, the degree of fit between 5 hydrogen technology and policy reflects the applicability of the policy. As shown in 6   Table 1.

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(2) Social recognition. Hydrogen energy as a new energy, social recognition of it 8 is also an important measure of its social. As shown in Table 1.

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As a new energy source, hydrogen production technology has abundant sources of 11 raw materials and complex hydrogen production processes. There are relatively few 12 researches on the development of hydrogen energy technology by coal companies. It is 13 reasonable to plan and deploy various technologies in different time periods and regions 14 For issues such as the order of development of hydrogen production, it is necessary to 15 conduct an objective and scientific evaluation of various hydrogen production 16 technologies. Therefore, the premise of the evaluation is to establish a scientific and 17 reasonable evaluation index system.  19 Based on the analysis of influencing factors in Chapter 3.1, the following 20 Comprehensive Evaluation Index system is established 21 Table 4 22 1 (1) Standardized treatment of indicators. In the comprehensive evaluation, due to 2 the existence of qualitative and quantitative different types of indicators, or the value 3 gap between indicators, different scale and other issues, resulting in the original 4 indicators in the calculation and analysis of the impact of the accuracy of evaluation.

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The presence of indicators with high numerical values has a greater impact on the whole, 6 and the role of indicators with lower numerical levels is relatively weakened. Therefore, 7 we need to standardize all indicators to improve the accuracy of the results. In this paper, 8 the indicator is standardized by the extreme difference method.

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(2) Consistent processing of indicator types. In the comprehensive evaluation of

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The article chooses the analytic hierarchy process to determine the weights. There 17 are two advantages to determine the weights through the analytic hierarchy process.
In this Formula： (0,1) ε ∈ is the resolution factor,experience is valued 0.5.    There are currently four types of hydrogen production technologies to be selected.

Data Collection
8 The data and related information come from enterprises such as experts, scholars 9 and university experts with professional knowledge and management experience.

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Based on the related literature and expert interview, five kinds of dimensions and 16 their parameters have been given.We establish a hierachical structure for their 17 comprehensive evaluation,which is shown in Table 7 and includes three levels, goal,

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(1)When calculating the weight of the first layer, they are scored by an expert jury, 11 starting from the five levels of energy, economy, environment, technology, and society, 12 and comparing their impact on the hydrogen production technology plan two by one, 13 so as to determine the weight of the indicator. The result of the judgment matrix of the 14 first layer is shown in Table 5.
15 Table 5 16 According to the calculation results, energy and environment are the first two   Table 6 3 4 (1) Build a weighted normalization matrix 5

Comprehensive evaluation based on gray correlation-TOPSIS method
Using the weights of each index calculated by the hierarchical analysis method, 6 the weighted normalization matrix is constructed with the index data after the non-scale 7 outline. 8 Table 7 9 Table 8 10 Table 9 11 Table 10 12 Table 11 13 ( Table 12 9 According to the formula (9), the gray association between each scheme and the

Results amd Analysis
In this paper, AHP-TOPSIS method and AHP-GC method are used to compare the 1 results of the proposed methods. The weight of each influencing factor adopted by the 2 three methods is the same. The closeness index results of the three methods are shown 3 in Table 14.
4 Table 14 5 It can be seen from Table 14 that the results of the three methods are basically 6 consistent and close, which shows that the proposed AGT is reasonable and feasible to  It can be seen from Fig. 2 that coke oven gas hydrogen production is the most 22 closely related hydrogen production technology, with a closeness of 0.5925, indicating 1 that coke oven gas hydrogen production is the preferred hydrogen production 2 technology for a mining group's transformation and development of hydrogen energy.

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On the one hand, because coke oven gas is compared with the traditional hydrogen 4 production method, hydrogen extraction is not only a more environmentally friendly 5 comprehensive utilization of resources, but also has very considerable economic to produce hydrogen, and the cost is low. The second in the ranking of relative closeness 10 is the traditional coal gasification hydrogen production, which has already been 11 produced on a large scale in my country, with relatively mature technology and low 12 cost, but there are also problems such as high carbon emissions and many gas impurities.

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The hydrogen production technology ranked last is hydrogen production by electrolysis 14 of water, with a relative closeness of 0.4851. Although its raw material is non-polluting 15 water, it consumes a lot of electric energy in its preparation, so it has relatively low 16 scores in economic and environmental dimensions.