DOI: 10.5281/zenodo.3890379
title: Hybrid LCA database generated using ecoinvent3.5 and EXIOBASE3

description: Hybrid LCA database generated using ecoinvent3.5 and EXIOBASE3, i.e., each process of the original ecoinvent3.5 database is added new direct inputs (coming from EXIOBASE3) deemed missing (e.g., services). Each process of the resulting hybrid database is thus not (or at least less) truncated and the calculated lifecycle emissions/impacts should therefore be closer to reality. For license reasons, only the added inputs for each process of ecoinvent are provided (and not all the inputs). <em>Why are there two versions?</em> One of the version corresponds to ecoinvent hybridized with the normal version of EXIOBASE and the other is hybridized with a capital-endogenized version of EXIOBASE3. <em>What does capital endogenization do?</em> It matches capital goods formation to the value chains of products where they are required. In a more LCA way of speaking, EXIOBASE in its normal version does not allocate capital use to value chains. It's like if ecoinvent processes had no inputs of buildings, etc. in their unit process inventory. For more detail on this, refer to (Södersten et al., 2019) or (Miller et al., 2019). <em>So which version do I use?</em> Using the version "with capitals" gives a more comprehensive coverage. Using the "without capitals" version means that if a process of ecoinvent misses inputs of capital goods (e.g., a process does not include the company laptops of the employees), it won't be added. It comes with its fair share of assumptions and uncertainties however. <em>How do I use the dataset?</em> First, to use it, you will need ecoinvent3.5 [cut-off] and EXIOBASE3 [product x product, year 2011]. In the two datasets of this package, only added inputs are given (i.e. inputs from EXIOBASE added to ecoinvent processes). Ecoinvent and EXIOBASE processes/sectors are not included, for copyright issues. You thus need both ecoinvent and EXIOBASE to calculate life cycle emissions/impacts. Module to get ecoinvent in a Python format: https://github.com/majeau-bettez/ecospold2matrix (make sure to take the most up-to-date branch) Module to get EXIOBASE in a Python format: https://github.com/konstantinstadler/pymrio (can also be installed with pip) If you want to use the "with capitals" version of the hybrid database, you also need to use the capital endogenized version of EXIOBASE, available here: https://zenodo.org/record/3874309. Choose the pxp version of the year you plan to study (which should match with the year of the EXIOBASE version). You then need to normalize the capital matrix (i.e., divide by the total output x of EXIOBASE). Then, you simply add the <em>normalized</em> capital matrix (K) to the technology matrix (A) of EXIOBASE (see equation below). Once you have all the data needed, you just need to apply a slightly modified version of the Leontief equation: \(\begin{equation} \textbf{q}^{hyb} = \begin{bmatrix} \textbf{C}^{lca}\cdot\textbf{S}^{lca} & \textbf{C}^{io}\cdot\textbf{S}^{io} \end{bmatrix} \cdot \left( \textbf{I} - \begin{bmatrix} \textbf{A}^{lca} & \textbf{C}^{d} \\ \textbf{C}^{u} & \textbf{A}^{io}+\textbf{K}^{io} \end{bmatrix} \right) ^{-1} \cdot \left( \begin{bmatrix} \textbf{y}^{lca} \\ 0 \end{bmatrix} \right) \end{equation}\) q<sup>hyb</sup> gives the hybridized impact, i.e., the impacts of each process including the impacts generated by their new inputs. C<sup>lca</sup> and C<sup>io</sup> are the respective characterization matrices for ecoinvent and EXIOBASE. S<sup>lca</sup> and S<sup>io</sup> are the respective environmental extension matrices (or elementary flows in LCA terms) for ecoinvent and EXIOBASE. I is the identity matrix. A<sup>lca</sup> and A<sup>io</sup> are the respective technology matrices for ecoinvent and EXIOBASE (the ones loaded with ecospold2matrix and pymrio). K<sup>io</sup> is the capital matrix. If you do not use the endogenized version, do not include this matrix in the calculation. C<sup>u</sup> (or upstream cut-offs) is the matrix that you get in this dataset. C<sup>d</sup> (or downstream cut-offs) is simply a matrix of zeros in the case of this application. Finally you define your final demand (or functional unit/set of functional units for LCA) as y<sup>lca</sup>. <em>Can I use it with different versions of ecoinvent?</em> No it can only work with ecoinvent3.5. Unfortunately ecoinvent changes the UUIDs of their process between each version and also introduces additional processes. <em>Can I use it with different versions/reference years of EXIOBASE?</em> Technically speaking, yes it will work, because the temporal aspect does not intervene in the determination of the hybrid database presented here. However, keep in mind that there might be some inconsistencies. For example, you would need to multiply each of the inputs of the datasets by a factor to account for inflation. Prices of ecoinvent are defined in €2005. The inputs were calculated for the year 2011 using a inflation factor of 1.13. <em>How do I link UUIDs of ecoinvent to metadata?</em> Ecospold2matrix stores all the metadata into the PRO matrix. <em>Why is the equation (I-A)<sup>-1</sup> and not A<sup>-1</sup> like in LCA?</em> IO and LCA have the same computational background. In LCA however, the convention is to represents outputs and inputs in the technology matrix. That's why there is a diagonal of 1s (the outputs, i.e. functional units) and negative values elsewhere (inputs). In IO, the technology matrix does not include outputs and only registers inputs as positive values. In the end, it is just a convention difference. If we call T the technology matrix of LCA and A the technology matrix of IO we have T = I-A. When you load ecoinvent using ecospold2matrix, the resulting version of ecoinvent will already be in IO convention and you won't have to bother with it. <em>Pymrio does not provide a characterization matrix for EXIOBASE, what do I do?</em> You can find an up-to-date characterization matrix (with Impact World+) for environmental extensions of EXIOBASE here: https://zenodo.org/record/3890339 If you want to match characterization across both EXIOBASE and ecoinvent (which you should do), here you can find a characterization matrix with Impact World+ for ecoinvent: https://zenodo.org/record/3890367 <em>It's too complicated...</em> The custom software that was used to develop these datasets already deals with some of the steps described. Go check it out: https://github.com/MaximeAgez/pylcaio. You can also generate your own hybrid version of ecoinvent3.5 using this software (you can play with some parameters like correction for double counting, inflation rate, change price data to be used, etc.).<strong> As of pylcaio v2.1, the resulting hybrid database (generated directly by pylcaio) can be exported and manipulated to brightway2.</strong> <em>Where can I get more information?</em> The whole methodology is detailed in (Agez et al., 2021). <br> If needed, I will be happy to help: maxime.agez@polymtl.ca
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