生物甲醇裂解制氢一体化系统及生命周期评价

    Integrated bio-methanol cracking hydrogen production system and its life cycle assessment

    • 摘要: 为了对生物甲醇裂解制氢一体化系统进行环境影响定量化评价和系统经济性动态分析,以无锡市某中小型甲醇裂解制氢厂为典型案例,构建系统生命周期模型,评估环境影响潜值并分析综合环境影响,同时进行经济可行性评估。结果表明,制氢阶段对环境影响最为显著,在大气酸化潜值(acidification potential,AP)、非生物资源耗竭潜值(abiotic depletion potential,ADP)和人体毒性潜值(human toxicity potential,HTP)3类环境影响类别中均占比70%以上,在HTP环境类别中占比高达90.47%。其次对环境有较大影响的是甲醇生产阶段和甲醇运输阶段。ADP、HTP和全球变暖效应(global warming potential,GWP)是对总环境影响最大的3类环境影响类别。环境影响敏感性分析表明,减少甲醇运输油耗和制氢电耗可有效减轻环境负面影响。生物甲醇生产模式的转变对碳排放减少影响显著,采用氢能运输可进一步降低排放。从经济角度来看,系统的投资回收期(payback period,PBP)为12.16 a,净现值(net present value,NPV)为211.87万元,内部收益率(internal rate of return,IRR)为13%。系统的盈利能力较高,资金流动性较强并且经济性较好。原料成本、碳价格和氢能源价格是影响经济可行性结果的关键因素,在氢能源价格较高和碳价提升的情景下,系统的经济竞争力显著增强。

       

      Abstract: Hydrogen energy can play a pivotal role in the energy transition and sustainable development. It is very urgent to optimize the energy structures and transition industries toward low-carbon solutions in recent years, particularly in the pursuit of carbon peaking and carbon neutrality. Fortunately, bio-methanol cracking hydrogen production can be expected to offer cost-effectiveness and scalability among the emerging technologies. However, it is still lacking in the environmental impact and economic assessment. In this study, a systematic quantitative assessment was conducted on the environmental impacts at each stage of the life lifecycle. A dynamic economic evaluation was also coupled for the decision-making and strategic deployment of bio-methanol cracking hydrogen production. A case study was selected as the medium-sized plant of methanol cracking hydrogen production in Wuxi City, Jiangsu Province, China. A comprehensive evaluation of the integrated system was selected to facilitate the environmental and economic performance. A life cycle model was developed to assess the environmental impacts. The potentials of environmental impacts were then calculated at each stage. Furthermore, some indicators were determined after economic evaluation, in order to balance the overall environmental footprint and the economic feasibility of the system. The results indicated that the hydrogen production stage contributed to the most significant environmental impacts, accounting for over 70% of categories, such as acidification potential (AP), abiotic depletion potential (ADP), and human toxicity potential (HTP). Notably, the HTP category was accounted for as much as 90.47%. The methanol production and transportation stages were also identified as substantial contributors to the environmental impacts. The ADP, HTP, and global warming potential (GWP) contributed the most to the overall environmental impact. While the least contribution was from the ozone depletion potential (ODP). Sensitivity analysis showed that the effective strategies greatly contributed to the minimum fuel consumption during methanol transportation. Negative environmental impacts were then mitigated to reduce the electricity usage in hydrogen production. The carbon emissions of the life cycle varied between 0.71 and 12.18 kg/kg , depending on the stage and scenario. Among the contributing factors, the bio-methanol production mode shared the most significant influence on the carbon emissions of the life cycle. Hydrogen energy was also used to reduce the emissions during methanol transportation. The costs of the integrated system were composed of the raw materials expenses, fixed capital investment, as well as operation and maintenance costs. While its revenue primarily stemmed from the hydrogen fuel sales. The economic indicators were obtained, with a payback period (PBP) of 12.16 years, a net present value (NPV) of 2.118 7 million yuan, and an internal rate of return (IRR) of 13%. Strong profitability, liquidity, and favorable economic performance were achieved in the bio-methanol cracking hydrogen production. Key influencing factors on the economic feasibility included raw material costs, carbon pricing, and hydrogen energy prices. The NPV ranged from -5.68×107 to 8.64×107 CNY in the various scenarios. Particularly, the economic competitiveness of the system was significantly enhanced in the scenarios with the higher hydrogen energy and carbon prices. The hydrogen energy prices enhanced the revenue potential of the system. While the higher carbon pricing also provided strong economic incentives for low-carbon technologies, further improving its financial viability.

       

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