低碳技术是实现中国双碳目标的关键之一,然而从生命周期角度而言,新技术的工业应用也需要额外的资源投入并会带来新排放,碳减排效果具有不确定性,因此需通过生命周期评价(LCA)量化所有单元过程对碳足迹的贡献,指导低碳技术的工艺设计和流程优化。传统的LCA方法依赖工厂清单数据调研,可定义为技术工业化应用后的事后评价,但对于尚处于试验规模研发的技术,难以获得LCA所需数据。因此,针对尚未工业应用的新兴技术,事前LCA方法论研究将有潜力成为未来产业生态学领域的重点方向。总结了目前事前LCA方法论存在的清单数据收集、系统边界定义和结果解释等主要问题,提出事前LCA方法除应用于粗略预估新技术潜在的碳足迹等环境影响外,更重要的功能是通过量化与新技术相关的工业生态系统的碳足迹现状作为新技术研发基准目标,发现和优化环境影响较大的过程,为工业应用提出低碳设计建议。通过归纳总结具有代表性的新兴技术事前LCA案例,发现基于试验规模数据计算得到碳足迹与实际工业规模有数量级差距,因此建议在研发过程中投入少量额外人力及软硬件资源,以实现工艺过程的放大模拟,预测其工业规模能耗和投入产出清单并开展生命周期环境影响评价。最后以废弃聚氯乙烯脱氯资源化技术碳足迹评估为例,通过融合基础试验、过程模拟和事前LCA方法量化不同反应物浓度、处理量、反应器设计、运行条件等过程变量对能源与原辅料消耗、直接排放、产物收率、废弃物产生量等过程投入产出清单的影响,并实现以碳足迹作为评价指标,指导新技术低碳工艺设计和运行条件的研发。

The development of low-carbon technologies is one of the essential pieces to achieve carbon peak and carbon neutrality in Chi⁃na. However, from a life-cycle perspective, the industrial application of new technologies also requires additional resource inputs andbrings new emissions, and the carbon reduction effect is uncertain. Thus, life cycle assessment (LCA) is needed to quantify the contribu⁃tion of all unit processes to the carbon footprint, and to guide the process design and optimization of low-carbon technologies. For the con⁃ventional LCA, the environmental impacts are ex-post evaluated based on the industrial-scale production system, but it is difficult to ob⁃tain the data required for LCA for technologies that are still being developed at a pilot scale. Therefore, to evaluate the potential life-cycleenvironmental impacts of a technology under lab-scale development, the methodology development for ex-ante LCA will be a vital topic inthe field of industrial ecology. At first, the main issues about the methodology of ex-ante LCA were summarized, including the difficultyof modeling the inventory data, defining the system boundary, and result interpretation. In addition to the application of the ex-anteLCA method to roughly estimate the potential carbon footprint and other environmental impacts of new technologies, it Is proposed thata more important function is to identify and optimize processes with high environmental impacts by quantifying the current carbon footprintof industrial ecosystems related to new technologies as a baseline target for the research and development of new technologies, so as to makelow-carbon design recommendations for industrial applications. By summarizing representative cases of ex-ante LCA of emerging technolo⁃gies, it is found that there is an order of magnitude gap between the carbon footprint calculated based on pilot-scale data and the actual in⁃dustrial scale, so it is recommended to invest a small amount of additional manpower and software and hardware resources in the research anddevelopment process to realize the amplified simulation of the process, predict the energy consumption and input/ output lists of the industrialscale, and carry out the life-cycle environmental impact assessment. Finally, as a case study for guiding the low-carbon development oftechnologies, the green design of a Cl recovery process for PVC waste was revealed by the integration of experiment, simulation, and ex-anteLCA for quantifying the influence of process variables such as different reactant concentrations, treatment volumes, reactor designs, operat⁃ing conditions and other process variables on the list of process inputs and outputs, such as consumption of energy and raw and auxiliary ma⁃terials, direct emissions, product yields, and the amount of wastes generated. Meanwhile, it realizes the use of carbon footprint as an evalua⁃tion indicator to guide the research and development of low-carbon process design and operating conditions for new technologies.

0 引言

1 事前LCA方法论中需完善要点

   1.1 清单数据计算

   1.2 系统边界定义的局限性

   1.3 评价结果的解释

2 事前LCA的常见方法和结果对比

   2.1 基于试验数据估算碳足迹

   2.2 基于过程模拟数据计算碳足迹

   2.3 事前LCA指导新兴技术低碳设计

3 案例分析

   3.1 评价方法

   3.2 基于碳足迹的研发路线

4 结论