The objective of this paper was to provide LCA practitioners with recommendations and a framework for upscaling emerging technologies by reviewing upscaling methods applied so far in ex ante life cycle assessment (LCA). Web of Science was searched for articles published between 1990 and 2019 (April) using different variations of the term “ex ante LCA” as keywords. Suitable studies were reviewed to understand the key characteristics and main methodological principles of upscaling methods. A total of 18 studies were selected for literature review. Review results showed that most studies reported what a hypothetical upscaled technology would look like in the future. All studies described how they estimated data; they applied different data estimation methods, using process simulation, manual calculations, molecular structure models (MSMs) and proxies. Since the review results showed that most ex ante LCA studies followed similar upscaling steps, we developed a framework for the upscaling of emerging technologies in ex ante LCA consisting of three main steps: (1) projected technology scenario definition, (2) preparation of a projected LCA flowchart, and (3) projected data estimation. Finally, a decision tree was developed based on the review results that provides recommendations for LCA practitioners regarding the upscaling procedure in ex ante LCA. Our findings can be useful for LCA practitioners aiming at upscaling in ex ante LCA. We provide an overview of upscaling methods used in ex ante LCA and introduce a framework describing the steps involved in the upscaling process and a decision tree recommending an up-scaling procedure. The results show that in theory all data estimation methods described in this paper can be applied to estimate material flows, energy flows, and elementary flows (emissions and natural resource use). Finally, since different kinds of expertise are required for upscaling in ex ante LCA, we recommend that technology experts from different fields are involved in performing ex ante LCA, e.g., technology developers, LCA practitioners, and engineers.

中文翻译：

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新兴技术事前生命周期评估中使用的升级方法：综述

本文的目的是通过回顾迄今为止在事前生命周期评估 (LCA) 中应用的升级方法，为 LCA 从业者提供升级新兴技术的建议和框架。使用术语“事前 LCA”的不同变体作为关键字，在 Web of Science 中搜索了 1990 年至 2019 年（4 月）之间发表的文章。审查适当的研究以了解升级方法的关键特征和主要方法学原理。共选取 18 项研究进行文献综述。审查结果表明，大多数研究报告了假设的升级技术在未来会是什么样子。所有研究都描述了他们如何估计数据；他们应用了不同的数据估计方法，使用过程模拟、手动计算、分子结构模型 (MSM) 和代理。由于审查结果表明大多数事前 LCA 研究遵循类似的升级步骤，我们开发了一个框架，用于事前 LCA 中新兴技术的升级，包括三个主要步骤：(1) 预测技术场景定义，(2) 准备投影 LCA 流程图，以及 (3) 投影数据估计。最后，基于审查结果开发了一个决策树，为 LCA 从业者提供关于事前 LCA 升级程序的建议。我们的研究结果对于 LCA 从业者旨在扩大事前 LCA 的范围很有用。我们概述了事前 LCA 中使用的升级方法，并介绍了一个框架，描述了升级过程中涉及的步骤和推荐升级程序的决策树。结果表明，从理论上讲，本文描述的所有数据估算方法都可以用于估算物质流、能量流和基本流（排放和自然资源使用）。最后，由于事前 LCA 升级需要不同类型的专业知识，我们建议来自不同领域的技术专家参与执行事前 LCA，例如技术开发人员、LCA 从业人员和工程师。