The LCA Digital Commons is a free, US government-sponsored and hosted web-based data resource. Given that all of its data are publicly available, it is a popular choice for
practitioners. Thus, it is also a great resource for learning about what LCI data looks like, how to access it, and how to build models.
The main purpose of the Digital Commons is to act as a resource for US Department of Agriculture (USDA) agricultural data and, as a result, accessing the home page (at
https://www.lcacommons.gov/discovery) will filter access to those datasets. However, the US LCI database previously hosted by NREL (at http://www.nrel.gov/lci/), and mentioned extensively in Chapter 5, is also hosted via the Digital Commons website (at
https://www.lcacommons.gov/nrel/search). Given its comprehensiveness, most of the discussion in this book is related to use of the NREL data. The examples provided below are for accessing the NREL data source, which has slightly different metadata and contents than the USDA data but a similar method for searching and viewing.
The LCI data modules on the Digital Commons website can be accessed via searching or browsing. Brief overviews are provided for both options, followed by how to view and download selected modules. Before following the tutorial below, you should consider registering for an account on the Digital Commons website (you will need separate accounts for the USDA and NREL data). While an account is not required to view all of the data, it is required if you wish to download the data. You can copy and paste the data from a web browser instead of downloading but this sometimes leads to formatting errors.
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Browsing for LCI Data Modules on the Digital Commons (NREL)
Figure 5-15 shows the NREL Digital Commons home page, where the left hand side shows how the data modules are organized, including dataset type (elementary flows or unit processes), high-level categories (like transportation and utilities), and year of data8.
Figure 5-15: Excerpt of LCA Digital Commons Website Home Page
Clicking on the + icon next to the categories generally reveals one or more additional sub-categories. For example, under the Utilities category there are fossil-fired and other generation types. Clicking on any of the dataset type, category/subcategory or year checkboxes will filter the overall data available. The "order by" box will sort the resulting modules. Filtering by (checking) Unit processes and the Fossil fuel electric power generation category under Utilities, and ordering by description will display a subset of LCI data modules, as shown in Figure 5-16. A resulting process module can be selected (see below for how to do this and download the data).
Figure 5-16: Abridged View of LCA Digital Commons Browsing Example Results
8 The examples of the NREL US LCI Database in this section are as of July 2014, and may change in the future.
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Searching for an LCI data module via keyword
The homepage has a search feature, and entering a keyword such as electricity and pressing the Go button on the right hand side, as shown in Figure 5-17, will return a list of data modules within the NREL LCI database that have that word in the title or category, as shown in Figure 5-18.
Figure 5-17: Keyword search entry on homepage of NREL engine of LCA Digital Commons Website
Figure 5-18: Abridged Results of electricity keyword search
Figure 5-18 indicates that the search engine returns more than 100 LCI data modules (records) that may be relevant to "electricity". Some were returned because electricity is in the name of the process and others because they are in the Electric power distribution data category. When searching, you can order results by relevance, description, or year. Once a
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set of search results is obtained, results can be narrowed by filtering via the options on the left side of the screen. For example, you could choose a subset of years to be included in the search results, which can help ensure you use fairly recent instead of old data (as discussed along with Figure 5-14). You can also filter based on the LCI data categories available, in this case by clicking on the + icon next to the high-level category for Utilities, which brings up all of the subcategories under utilities. Figure 5-19 shows the result of a keyword search for 'electricity', ordered by relevance, and filtered by the Utilities subcategory of Fossil fuel electric power generation and by data for year 2003. The fifth search result listed is the same one mentioned in the chapter that forms the basis of the process flow diagram example.
Figure 5-19: Abridged Results of electricity keyword search, ordered and filtered
Selecting and viewing an LCI data module
When you have searched or browsed for a module and selected by clicking on it, the module detail summary is displayed, as in Figure 5-20.
Life Cycle Assessment: Quantitative Approaches for Decisions That Matter – lcatextbook.com Figure 5-20: Details for Electricity, bituminous coal process on LCA digital commons
The default result is a view of the Activity tab, which was shown in Figure 5-11. The
information available under the Modeling and Administrative tabs was presented in Figure 5-12 and Figure 5-13. Finally, an abridged view of the information available on the Exchanges tab was also shown in Figure 5-6. Not previously mentioned is that the module can be
downloaded by first clicking on the shopping cart icon in the top right (adjacent to the
"Next item" tag). This adds it to your download cart. Once you have identified all of the data you are interested in, you can view your current cart (menu option shown in Figure 5-21) and request them all to be downloaded (Figure 5-22).
Figure 5-21: Selection of Current Cart Download Option on LCA Digital Commons
Life Cycle Assessment: Quantitative Approaches for Decisions That Matter – lcatextbook.com Figure 5-22: Cart Download Screen on LCA Digital Commons
After clicking download, you will be sent a link via the e-mail in your account registration.
As noted, the format will be an Ecospold XML file. For novices, viewing XML files can be cumbersome, especially if just trying to look at flow information. While less convenient, the download menu (All LCI datasets submenu) will allow you to receive a link to a ZIP file archive containing all of the NREL modules in Microsoft Excel spreadsheet format (or you can receive all of the modules as Ecospold XML files). You can also download a list of all of the flows and processes used across the entire set of about 600 modules.
A spreadsheet of all flows and unit processes in the US LCI database (and their categories) is on the www.lcatextbook.com website in the Chapter 5 folder.
When uncompressed the Electricity, bituminous coal, at power plant module file has four worksheets, providing the same information as seen in the tabs of the Digital
Commons/NREL website above. The benefit of the spreadsheet file, though, is the ability to copy and paste that values into a model you may be building. We will discuss building spreadsheet models with such data in Section 4 of this advanced material.
Section 2 – Accessing LCI Data Modules in SimaPro
As mentioned in the chapter, SimaPro is a popular commercial software program specifically aimed at building quantitative LCA models. Its value lies both in these model-building support activities as well as in being able to access various datasets from within the program.
Commercial installations of SimaPro cost thousands of dollars, but users may choose commercial databases (e.g., ecoinvent) to include in the purchase price. Regardless of which databases are chosen, SimaPro has the ability to use various other free datasets (e.g., US NREL, ELCD, etc.). This tutorial assumes that such databases have already been installed and will demonstrate how to find the same US NREL-based LCI data as in Section 1.
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This tutorial also does not describe any of the initial steps needed to purchase a license for or install SimaPro on your Windows computer or server. It will only briefly mention the login and database selection steps, which are otherwise well covered in the SimaPro guides provided with the software.
Note that SimaPro refers to the overall modeling environment of data available as a
"database" and individual LCI data sources (e.g., ecoinvent) as "libraries". After starting SimaPro, selecting the database (typically called "Professional"), and opening or creating a new project of your choice, you will be presented with the screen in Figure 5-23. On the left side of the screen are various options used in creating an LCA in the tool. By default the
"processes" view is selected, showing the names and hierarchy of all processes in the currently selected libraries of the database. This list shows thousands of processes (and many of those will be from the ecoinvent database given its large size).
Figure 5-23: Default View of Processes in Libraries When Starting SimaPro
You can narrow the processes displayed by clicking on "Libraries" on the left hand side menu, which will display Figure 5-24. Here you can select a subset of the available libraries for use in browsing (or searching) for process data. You can choose "Deselect all" and then to follow along with this tutorial, click just the "US LCI" database library in order to access only the US NREL LCI data.
Life Cycle Assessment: Quantitative Approaches for Decisions That Matter – lcatextbook.com Figure 5-24: List of Various Available Libraries in SimaPro
If you then click the "Processes" option on the left hand side, you return to the original screen but now SimaPro filters and shows only processes from the selected libraries, as in Figure 5-25. Many of the previously displayed processes are no longer displayed.
Figure 5-25: View of Processes and Data Hierarchy for US-LCI Library in SimaPro
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Now that you have prepared SimaPro to look for the processes in a specific database library, you can browse or search for data.
Browsing for LCI Data Modules in SimaPro
Looking more closely at Figure 5-25, the middle pane of the window shows the categorized hierarchy of data modules (similar to the expandable hierarchy list in the Digital Commons tool). However, these are not the same categories used on the NREL LCA Digital
Commons website. Instead, they are the standard categories used in SimaPro for processes in any library. Clicking on the + icon next to any of the categories will expand it and show its subcategories. To find the Electricity, bituminous coal process, expand the Energy category then expand Electricity by fuel, then expand coal, resulting in a screen like Figure 5-26.
Several of the other processes burning coal to make electricity and mentioned in the chapter would also be visible.
Figure 5-26: Processes Shown by Expanding Hierarchy of Coal-Sourced Electricity in SimaPro
The bottom pane shows some of the metadata detail for the selected process. By browsing throughout the categories (and collapsing or expanding as needed) and reading the metadata you can find a suitable process for your model. The tutorial will demonstrate how to view or download such data after briefly describing how to search for the same process.
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Searching for a process in SimaPro
Once libraries have been specified as noted above, clicking on the magnifying glass icon in the toolbar brings up the search interface as shown in Figure 5-27. You enter your search term in the top box, and then choose from several search options. If you are just looking for process data (as in this tutorial) then you would want to restrict your choice of where to look for the data to only libraries you have currently chosen (i.e., via the interface in Figure 5-24) rather than all libraries. This will also make your search return results more quickly.
Note the default search only looks in the names of processes, not in the metadata (the "all fields" option changes this behavior).
Figure 5-27: Search Interface in SimaPro
Figure 5-28 shows the result of a narrowed search on the word "electricity" in the name of processes only in "Current project and libraries" and sorted by the results column "Name".
Since we have already selected only the US LCI database in libraries, the results will not include those from ecoinvent, etc. One of the results is the same Electricity, bituminous coal, at power plant process previously discussed.
Life Cycle Assessment: Quantitative Approaches for Decisions That Matter – lcatextbook.com Figure 5-28: Results of Modified Search for Electricity in SimaPro
By clicking "Go to" in the upper right corner of the search results box, SimaPro "goes to"
the same place in the drill-down hierarchy as shown in Figure 5-26.
Viewing process data in SimaPro
To view process data, choose a process by clicking on it (e.g., as in Figure 5-26) and then click the View button on the right hand side. This returns the process data and metadata overview shown in Figure 5-29. Similar to the Digital Commons website, the default screen shows high-level summary information for the process. Full information is found in the documentation and system description tabs.
Figure 5-29: Process Data and Metadata Overview in SimaPro
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Clicking on the input-output tab displays the flow data in Figure 5-30, which for this process is now quite familiar. If you need to download this data, you can do so by choosing
"Export" in the File menu, and choosing to export as a Microsoft Excel file.
Figure 5-30: View of Process Flow Data (Inputs and Outputs) in SimaPro