Study On Technical And Economic Evaluation System Of Hydrogen Production From Organic Solid Wastes

Hydrogen energy is recognized as the cleanest secondary energy in the world and has a low heating value of 28,966 kCal/kg,considering as the highest calorific-value fuel among fossil fuels,synthetic fuels,and biofuels.Further,it is widely used in transportation,metallurgy,and chemical industries.Nowadays,wastes with high content of carbon,hydrogen,and oxygen are seemed to be the substitute towards fossil fuels in hydrogen production.Following the high-quality development of China’s economy and in-depth enhancement of waste classification,these opportunities give a good foundation for the utilization of wastes in hydrogen production.Besides,recently,the state subsidies for waste incineration in power generation projects are declining,let the profitability of the projects seriously affected due to the abatement of the on-grid tariff subsidies.Therefore,the utilization of high calorific-value classified wastes in hydrogen production may open a new way in facing the predicaments of the subsidy repayment and environmental issues due to organic solid wastes（OSWs）pollution,further promoting China’s hydrogen energy developing.The industrialization project of hydrogen production technology from OSWs has not yet appeared in China.There are few research results on project investment risk and operation risk,and there are few references at home and abroad.Through the research on the technical economy of hydrogen production from OSWs,the transformation of the technical achievements of hydrogen production from OSWs can be promoted.Based on the sub project of the national key R&D plan project"economic evaluation of hydrogen production technology from organic solid waste in multi-source cities",this thesis aims at the evaluation of material flow and energy flow conversion efficiency,carbon emission and carbon reduction,and economy of hydrogen production technology from OSWs;Carry out in-depth and systematic research on scientific issues such as economic risk analysis,in order to expand the method system of low-carbon technology economic evaluation and open up a new paradigm of low-carbon technology economic evaluation.The main research contents and conclusions are as follows.（1）The establishment of material and energy flow models for hydrogen production and energy utilization from OSWs.The constructed hydrogen production material flow analysis and evaluation model are composed through the macroscopic flux material flow and microscopic element material flow.Moreover,the flux material flow ranges from the input of wastes,water,and auxiliary materials towards the output of resource and energy-based products such as hydrogen,liquid carbon dioxide,recycled metals,and recycled plastic masterbatches,in order to evaluate the input and output of the materials at macro level.Despite,the research on the flux material flow has formed the units of solid waste gasification hydrogen production processes,including solid waste sorting,drying,molding and feeding unit,air separation unit,gasification unit,synthesis gas purification and compression post-processing unit,high-efficiency hydrogen production unit,and carbon dioxide liquefaction unit.In the pre-treatment unit,the domestic wastes are manufactured into RDF and react with oxygen and water vapour to produce syngas that rich in carbon monoxide（CO）and hydrogen（H₂）.Then,the syngas produced will undergo wet desulfurization and being compressed under sulphur-tolerant water gas shift technology,as CO in the syngas may react with steam to obtain process gas with high amount of CO₂ and H₂.The process gas will further treat with desulfurization and decarbonization to mitigate the CO₂ and H₂S.Finally,H₂ with high purity is obtained after PSA pressure swing adsorption technology.The quantitative relationship between the conversion and fate of the main elements such as C,H,O,N,and S in the wastes in each process unit of hydrogen production is analyzed through the element material flow.Simultaneously,the conversion and utilization efficiency of the main elements is evaluated.Besides,the energy flow analysis method and model of solid waste hydrogen production based on material balance and energy balance are established,further,the energy-saving amount of standard coal for the product produced by the project to replace similar fossil fuels is calculated.According to the standard coal data of energy flow based on material flow,the overall distribution of material and energy flow and the input and output of the gasification and hydrogen production process are obtained via the energy flow model.Based on the data,the energy flow of the system and the conversion efficiency of energy at the main process nodes are analyzed.（2）The carbon emission and carbon emission reduction accounting model of hydrogen production from OSWs is developed.For the accounting of hydrogen production and carbon emission reduction of OSWs such as domestic garbage,firstly,the boundary of hydrogen production and carbon emission system is delimited and the types of greenhouse gas emissions are determined,and then the baseline emissions and project activity emissions are calculated.The emission reduction is equal to the baseline emissions minus the project activity emissions and leakage.The baseline emission model of hydrogen production system includes six parts:emissions from fossil carbon in hydrogen production raw materials,carbon emissions from alternative gasoline fuel,carbon emissions from alternative pure plastic particle production,carbon dioxide emissions from alternative traditional carbon dioxide product processing energy consumption,carbon dioxide emissions from alternative fossil energy consumed by traditional heating steam production and permanent emission reduction formed by carbon dioxide geological storage.Emissions from project activities refer to emissions from relevant energy consumed by hydrogen production system activities,mainly including emissions from power consumption of hydrogen production system,carbon dioxide emissions from hydrogen fuel filling and transportation,and carbon dioxide emissions from fossil energy consumed by carbon dioxide geological storage.Referring to the emission factor data in relevant CDM methodology and relevant literature,the specific emission factors of hydrogen production system are calculated,and the carbon emission reduction data of hydrogen production system are obtained by using the established baseline emission model,project activity emission model and carbon emission reduction model.Combined with the factor emission method,the carbon emission reductions under the three scenarios of carbon dioxide as a product,geological storage,no utilization and no storage are calculated.（3）The technical and economic evaluation SD model of hydrogen production system from OSWs is established.The model mainly includes subsystem models such as project investment simulation,cost simulation,income simulation,profit simulation and cash flow simulation.The financial indexes such as profitability,net cash flow,investment payback period and net income of the project are analyzed.The price parameters of input and output materials of hydrogen production system are determined,and the model variable parameters such as construction investment,construction cycle,loan interest and operation cycle are estimated.Through the model simulation,the input-output economic information flow data of the economic system of hydrogen production system are obtained,mainly including cost,annual average EBIT,annual average net profit after income tax,internal rate of return,financial net present value,investment payback period,etc.The profitability of hydrogen production from OSWs was analyzed.Under the initial evaluation input conditions,through the analysis of after tax investment financial internal rate of return IRR,after tax financial net present value NPV,investment payback period P_t,capital net profit rate,asset liability ratio and other economic evaluation indicators.From the model simulation results,the hydrogen production from OSWs does not rely on the government waste treatment fee,but also has good profitability,which is less affected by the national and local financial waste treatment fee subsidies.At the same time,according to the carbon emission reduction accounting data,the impact of carbon emission reduction revenue and emission reduction cost on the economy of the project is preliminarily analyzed by using the technical and economic evaluation system dynamics model.Carbon emission trading can increase the financial internal rate of return by 2-3 percentage points.Carbon emission trading increases the income,but due to the small proportion of carbon trading income,it can not play a decisive role in the profit and loss of investment on the whole.The thesis also analyzes the carbon trading income of carbon dioxide emission reduction of geological storage,and comes to the conclusion that because the geological storage cost is much higher than the carbon emission trading income,enterprises have no economic driving force to carry out carbon dioxide geological storage.（4）A combined SRM model based on SD system dynamics,RSM response surface model and MCS Monte Carlo simulation is proposed.The SRM model can be used for interval quantitative analysis of multi-objective technical and economic indicators under different scenarios.Due to the lack of engineering data for hydrogen production from organic solid waste as reference,when a new project is built in the future,various sensitive factors might affect the technical and economic feasibility of the hydrogen production system.In order to encourage the investors and lawmakers to evaluate the technical and economic system pricing of hydrogen production projects in the future quantitatively,this dissertation builds a dynamic technical and economic simulation model of the organic solid waste hydrogen production system based on the system dynamics.The model can study the correlation and interaction between the indicators in the technical and economic evaluation of the hydrogen production system.Further,it can reveal the changes of the main factors,identify the main indicators,and determine the feasibility of the project.Moreover,based on the initial technical and economic simulation results of system dynamics,this dissertation also identifies the factors that are sensitive to the technical and economic system,and determines the level of the factors.According to the response surface model,the combined factors and levels are brought into the system dynamics technical and economic simulation model to obtain the response surface.Then,based on the test results,statistical software Minitab is used to establish a regression equation in line with the sensitive factors and multi-objectives.Using the regression equations of sensitive factors and multi-objectives,Monte Carlo simulation of the interval distribution of target parameters in various scenarios and the certainty or probability of occurrence in a certain interval are carried out.In short,this dissertation analyses the technical and economic evaluation scenarios of hydrogen production system along the logical sequence of SD-SRM-SD-MCS and forms the combined SRM model.Besides,this dissertation also simulates sensitive factors such as hydrogen and carbon dioxide product prices,waste treatment subsidies,and the cost increment of geological storage of carbon dioxide in order to identify the profitability of solid waste hydrogen production projects and the key points of risk prevention and control under uncertain conditions.The relevant results can be provided for the government as a reference to price the waste treatment fees,further,as a determination of the franchise period and the decision-making of project investors.From the perspectives of carbon emission reduction and carbon emission trade,the economic motivation of enterprises to invest in carbon emission reduction is analyzed.It is found out that the income of geological storage of carbon dioxide is far lower than its cost.The companies have no economic driving force to carry out carbon dioxide geological storage at this condition.If carbon dioxide goes to geological storage,it will increase the operation cost,so it is necessary to increase the subsidy of waste treatment fee to a reasonable price,or extend the franchise period to reasonable period.Through these measures,the investment risk of the project can be controlled to a certain extent,which also points out the direction and calculation method of reasonable pricing level for the pre investment negotiation between investors and relevant government departments.Overall,the internal rate of return of the project is higher than the industry benchmark rate of return.The project is economically feasible and the investment risk is controllable through relevant negotiations between the enterprise and the government.The main innovations of this thesis are:（1）The analysis model of material flow and energy flow of hydrogen production from OSWs is established,and the migration and transformation ways of flux material flow,element material flow and energy flow are revealed;The evaluation index system of hydrogen production technology from OSWs based on material flow and energy flow is constructed,and the conversion efficiency of material and energy of hydrogen production technology from OSWs is evaluated.（2）The carbon emission accounting boundary,emission factors and emission list of hydrogen production system are determined,the baseline emission model,project activity emission model and carbon emission reduction model of hydrogen production from OSWs system are constructed,and the carbon emission reduction of hydrogen production from OSWs technology is calculated under the three conditions of carbon dioxide as product,geological storage and direct emission.（3）The simulation model of dynamic technical and economic evaluation of hydrogen production system is constructed,the transfer process from material flow and energy flow to value flow of hydrogen production from OSWs is analyzed,the coupling of technical evaluation and economic evaluation is realized,and the impact of carbon trading price on the economic feasibility of hydrogen production from OSWs technology is simulated and calculated.（4）The SRM combination model of technical and economic risk analysis is established,and the interval measurement of the main parameters of the technical and economic evaluation of hydrogen production from OSWs is proposed,which solves the problem that the parameters of the traditional technical and economic evaluation model are difficult to carry out probabilistic risk analysis;The influence of main economic risk factors of hydrogen production system on the uncertainty of technical and economic indicators is calculated.