Fix KeyError In PyPSA-Eur's CO2 Sequestration Build

Hey guys! Have you ever encountered a pesky KeyError while working with PyPSA-Eur, especially when dealing with CO2 sequestration potentials? It's a common hiccup, and trust me, you're not alone! This article dives deep into a specific KeyError issue that arises in the build_co2_sequestration_potentials rule when running the default configuration in PyPSA-Eur. We'll break down the problem, explain why it happens, and provide a straightforward solution to get you back on track. So, if you're scratching your head over this error, stick around – we've got you covered!

This error typically surfaces when the script attempts to read specific files related to CO2 storage units and traps. The core of the issue lies in a discrepancy between the expected field name (id) and the actual field name (ID) used in the data files. Let's get into the nitty-gritty details to help you understand and resolve this problem efficiently. This comprehensive guide will not only help you fix the error but also provide insights into the underlying processes, making you a more confident PyPSA-Eur user. We will explore the tracebacks, pinpoint the exact location of the error, and offer a step-by-step solution. By the end of this article, you’ll have a solid understanding of how to tackle this KeyError and prevent it in the future. So, let’s dive in and get those CO2 sequestration potentials building smoothly!

The KeyError in the build_co2_sequestration_potentials script is a common stumbling block for those working with PyPSA-Eur, particularly when CO2 sequestration is a key component of your simulations. This error arises during the execution of the build_co2_sequestration_potentials rule, specifically when the script tries to map storage capacities. The root cause? A simple yet crucial mismatch in field names within the data files. The script expects a field named id, but the actual files use ID. This discrepancy leads to the KeyError: '['id'] not in index', effectively halting the process. To really grasp this, let's dissect the traceback provided. The error occurs within the create_capacity_map_storage function, where the script attempts to read spatial data using GeoPandas. GeoPandas, a powerful tool for working with geospatial data in Python, is used here to read KML files containing information about CO2 storage sites. These KML files, such as CO2Stop_Polygons Data/StorageUnits_March13.kml and CO2Stop_Polygons Data/DaughterUnits_March13.kml, are crucial for mapping the potential for CO2 sequestration. The traceback points directly to the line where the script tries to select data based on the id field: gdf = gpd.read_file(map_fn)[sel]. Because the expected id field doesn't exist, GeoPandas throws a KeyError. To further illustrate, imagine you're searching for a specific book in a library catalog. If the catalog lists the book's ID as "BookID" but you search for "id", you won't find it. Similarly, the script is looking for "id" in the data files, but it’s actually labeled as "ID". This mismatch is the heart of the problem. This issue highlights the importance of data consistency and the need to ensure that scripts align with the structure of the data they process. In the following sections, we’ll delve deeper into how to identify and rectify this mismatch, ensuring your PyPSA-Eur simulations run without a hitch.

To effectively tackle this KeyError, it's essential to be able to reproduce it reliably. This section provides a straightforward, step-by-step guide to recreate the error in your PyPSA-Eur environment. By following these steps, you can confirm that you're facing the same issue and then confidently apply the solution we'll discuss later. First, ensure you have PyPSA-Eur installed and set up correctly. This typically involves cloning the repository, creating a Conda environment, and installing the necessary dependencies. If you're unsure about these steps, refer to the official PyPSA-Eur documentation for detailed instructions. Next, navigate to your PyPSA-Eur directory in your terminal. This is where you'll execute the command that triggers the error. Now, the magic command that unveils the KeyError is: snakemake -call all --configfile config/config.default.yaml. This command tells Snakemake, the workflow management system used by PyPSA-Eur, to execute all rules defined in the workflow, using the default configuration file. The --configfile flag specifies the configuration file to use, which in this case is config.default.yaml. This file contains the default settings for the simulation, including the CO2 sequestration options that lead to the error. Once you run this command, Snakemake will start executing the workflow. It will proceed until it reaches the build_co2_sequestration_potentials rule. If the regional CO2 sequestration potential is enabled (which is the default setting), the script will attempt to read the KML files and, as expected, encounter the KeyError. You should see a traceback similar to the one described earlier, confirming that the error is indeed reproducible. By reproducing the error, you've taken the first crucial step towards resolving it. You now have a clear understanding of how to trigger the issue, which will be invaluable as we move on to implementing the fix. In the following sections, we'll explore the exact location of the problematic code and how to modify it to resolve the KeyError.

To effectively fix the KeyError in build_co2_sequestration_potentials, we need to pinpoint the exact location in the code where the error occurs. This involves examining the traceback and understanding the flow of execution within the script. Let's dissect the issue step by step to make sure we're all on the same page. The traceback usually points to the create_capacity_map_storage function within the build_co2_sequestration_potentials.py script. This function is responsible for creating a capacity map for CO2 storage sites by reading data from KML files. The crucial line of code that triggers the KeyError is typically: gdf = gpd.read_file(map_fn)[sel]. This line uses GeoPandas (gpd) to read a spatial data file (map_fn) and then attempts to select a subset of the data ([sel]). The selection [sel] is where the problem lies. It tries to filter the data based on the id field, which, as we've discussed, doesn't exist in the KML files. The files in question, such as data/CO2JRC_OpenFormats/CO2Stop_Polygons Data/StorageUnits_March13.kml and data/CO2JRC_OpenFormats/CO2Stop_Polygons Data/DaughterUnits_March13.kml, use ID instead of id as the field name for identification. To verify this, you can manually open these KML files using a text editor or a GIS software and inspect their structure. You'll notice that the attribute fields indeed use ID rather than id. This discrepancy between what the script expects (id) and what the data provides (ID) is the root cause of the KeyError. The script is essentially trying to access a non-existent column, leading to the error. Understanding this mismatch is key to crafting the correct solution. We need to modify the script to align with the actual data structure. This means replacing all instances where the script refers to the id field with ID. In the next section, we'll walk through the exact steps to make this change and resolve the KeyError.