PurposeElementary flows are essential components of data used for life cycle assessment. A standard list is not used across all sources, as data providers now manage these flows independently. Elementary flows must be consistent across a life cycle inventory for accurate inventory analysis and must correspond with impact methods for impact assessment. With the goal of achieving a global network of LCA databases, a critical review of elementary flow usage and management in LCA data sources was performed.MethodsFlows were collected in a standard template from various life cycle inventory, impact method, and software sources. A typology of elementary flows was created to identify flows by types such as chemicals, minerals, land flows, etc., to facilitate differential analysis. Twelve criteria were defined to evaluate flows against principles of clarity, consistency, extensibility, translatability, and uniqueness.Results and discussionOver 134,000 elementary flows from six LCI databases, three LCIA methods, and three LCA software tools were collected and evaluated from European, North American, and Asian Pacific LCA sources. The vast majority were typed as “Element or Compound” or “Group of Chemicals” with less than 10% coming from the other seven types. Many lack important identifying information including context information (environmental compartments), directionality (LCIA methods generally do not provide this information), additional clarifiers such as CAS numbers and synonyms, unique identifiers (like UUIDs), and supporting metadata. Extensibility of flows is poor because patterns in flow naming are generally complex and inconsistent because user-defined nomenclature is used.ConclusionsThe current shortcomings in flow clarity, consistency, and extensibility are likely to make it more challenging for users to properly select and use elementary flows when creating LCA data and make translation/conversion between different reference lists challenging and loss of information will likely occur.RecommendationsWe recommend the application of a typology to flow lists, use of unique identifiers and inclusion of clarifiers based on external references, setting an exclusive or inclusive nomenclature for flow context information that includes directionality and environmental compartment information, separating flowable names from context and unit information, linking inclusive taxonomies to create limited patterns for flowable names, and using an encoding schema that will prevent technical translation errors.

中文翻译：

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对 LCA 数据中的基本流进行批判性审查

目的基本流程是用于生命周期评估的数据的基本组成部分。并非所有来源都使用标准列表，因为数据提供者现在独立管理这些流。基本流必须在整个生命周期清单中保持一致，以进行准确的清单分析，并且必须与影响评估的影响方法相对应。为了实现 LCA 数据库的全球网络，对 LCA 数据源中的基本流使用和管理进行了严格审查。MethodsFlows 是从各种生命周期清单、影响方法和软件源收集在标准模板中的。创建了基本流量类型学，以按化学品、矿物、土地流量等类型识别流量，以促进差异分析。定义了 12 个标准来根据清晰性、一致性、可扩展性、可翻译性和唯一性原则评估流程。结果和讨论来自欧洲、北美的六个 LCI 数据库、三种 LCIA 方法和三个 LCA 软件工具的超过 134,000 个基本流程被收集和评估和亚太地区 LCA 来源。绝大多数被分类为“元素或化合物”或“化学组”，其他七种类型的不到 10%。许多缺乏重要的识别信息，包括上下文信息（环境隔间）、方向性（LCIA 方法通常不提供此信息）、CAS 编号和同义词等附加说明符、唯一标识符（如 UUID）和支持元数据。