Existing Data Updates

Many of the raw data inputs for PUDL are published on a annual or monthly basis. These instructions explain the process for integrating new versions of existing data into PUDL.

We update EIA monthly data and EPA CEMS hourly data on a quarterly basis.

EIA typically publishes an “early release” version of their annual data in the summer followed by a final release in the fall. Our data_maturity column indicates which version has been integrated into PUDL (“final” vs. “provisional”). This column also shows when data are derrived from monthly updates (“monthly_update”) or contain incomplete year-to-date data (“incremental_ytd”).

FERC publishes form submissions on a rolling basis meaning there is no official date that the data are considered final or complete. To figure out when the data are likely complete, we compare the number of respondents from prior years to the number of current respondents. We usually update FERC once a year around when we integrate EIA’s final release in the fall.

To see what data we have available for each dataset, click on the links below and look at the “Years Liberated” field.

1. Obtain Fresh Data

1.1) Add a new copy of the raw PUDL inputs from agency websites using the tools in the pudl-archiver repository. If the structure of the web pages or the URLs have changed, you may need to update the archivers themselves.

1.2) Update the dictionary of production DOIs in pudl.workspace.datastore to refer to the new raw input archives.

1.3) In pudl.metadata.sources.SOURCES, update the working_partitions to reflect the years, months, or quarters of data that are available for each dataset and the records_liberated to show how many records are available. Check to make sure other fields such as source_format or path are still accurate.


If you’re updating EIA861, you can skip the rest of the steps in this section and all steps after step two because 861 is not yet included in the ETL.

1.4) Update the partitions of data to be processed in the etl_full.yml and etl_fast.yml settings files stored under src/pudl/package_data/settings in the PUDL repo.

1.5) Use the pudl_datastore script (see Working with the Datastore) to download the new raw data archives in bulk so that network hiccups don’t cause issues during the ETL.

2. Map the Structure of the New Data

A. EIA Forms

EIA often alters the structure of their published spreadsheets from year to year. This includes changing file names; adding, removing, or re-ordering spreadsheet pages; changing the number of header and footer rows; and adding, removing, re-ordering, or re-naming the data columns. We track this information in the following files which can be found under src/pudl/package_data in the PUDL repository:

  • ${data_source}/file_map.csv: Paths (within the annual zip archive) to the files we parse.

  • ${data_source}/page_map.csv: Mapping between the named spreadsheet pages we refer to across years, and the numerical index of that page within the workbook.

  • ${data_source}/skiprows.csv: A per-page, per-year number of rows that should be skipped when reading the spreadsheet.

  • ${data_source}/skipfooter.csv: A per-page, per-year number of rows that should be ignored at the end of the page when reading the spreadsheet.

  • ${data_source}/column_maps/${page_name}.csv: A mapping from annual spreadsheet columns to consistent inter-year column names that we refer to in the raw dataframes during the extract step. The spreadsheet columns can be referred to either by their simplified snake_case column header (in eia860, eia860m, and eia923) or numerical column index (eia861).

Here ${data_source} is one of our data source short codes (eia860, eia923 etc.) and ${page_name} is a label we use to refer to a given spreadsheet tab over the years (e.g. boiler_fuel). However page_name does not necessarily correspond directly to PUDL database table names because we don’t load the data from all pages, and some pages result in more than one database table after normalization.

2.A.1) If you’re adding a new year, add a column for the new year of data to each of the aforementioned files. If there are any changes to prior years, make sure to address those too. (See note above). If you are updating early release data with final release data, replace the values in the appropriate year column.


If you are adding EIA’s early release data, make sure the raw files have Early_Release at the end of the file name. This is how the excel extractor knows to label the data as provisional vs. final.

If you are updating early release data to final release data - early release files tend to have one extra row at the top and one extra column on the right of each file indicating that it is early release. This means that the skiprows and column map values will probably be off by 1.

2.A.2) If there are files, spreadsheet pages, or individual columns with new semantic meaning (i.e. they don’t correspond to any of the previously mapped files, pages, or columns) then create new mappings to track that information over time.


In all of the the above CSV files we use a value of -1 to indicate that the data does not exist in a given year.

B. FERC Form 714

FERC Form 714 is distributed as an archive of CSV files, each of which spans all available years of data. This means there’s much less structure to keep track of. The main thing that changes from year to year is the names of the CSV files within the ZIP archive.

2.B.1) Update the mapping between extracted dataframes and those filenames in the pudl.extract.ferc714.TABLE_FNAME dictionary.

2.B.2) The character encodings of these CSV files may vary with some of them using iso-8859-1 (Latin) rather than utf-8 (Unicode). Note the per-file encoding in pudl.extract.ferc714.TABLE_ENCODING and that it may change over time.

3. Test Data Extraction

A. EIA Forms

3.A.1) You can either materialize the raw assets (ex: raw_eia860) in Dagster (learn more about Dagster in Running the ETL Pipeline) or use the Jupyter notebook devtools/eia-etl-debug.ipynb to run the extract process for a given data set. There are hundreds of columns mapped across all the different EIA spreadsheets, you’ll almost certainly encounter typos or errors that will cause the extraction to fail. Interpret these errors and revise your work from step 2. Using Dagster will help speed up the debugging process because it allows you to load individual, problematic assets rather than the whole suite of tables from a source.


If you’ve created or removed any assets, you’ll need to refresh the code location in Dagster before materializing any assets. You can do this by clicking on the circular arrow in the upper left hand corner next to the text “Job in <NAME OF JOB>”.

B. FERC Form 1

3.B.1) Clone the all of the FERC 1 data (including the new year) into SQLite with:

ferc_to_sqlite src/pudl/package_data/settings/etl_full.yml

This is necessary to enable mapping associations between the FERC 1 and EIA plants and utilities later.

3.B.2) Like EIA, you can either materialize the raw assets in Dagster or use the devtools/ferc1-etl-debug.ipynb notebook to run the extract process for each table.


3.C.1) The CEMS data are so large that it doesn’t make sense to store a raw and cleaned version of the data in the database. We’ll test the extraction and transformation steps together in the next section.

4. Update Table & Column Transformations

Currently, our FERC and EIA tables utilize different transform processes.

A. EIA Forms

4.A.1) You can either materialize the _core (clean) and _core (normalized) dagster asset groups for your dataset of interest (ex: _core_eia860 and core_eia860) or use the EIA ETL Debugging notebook mentioned above to run the initial transform step on all tables of the new year of data. As mentioned in 3.A.1, the debugging process is significantly faster with Dagster. If any new tables were added in the new year, you will need to add a new transform function for the corresponding dataframe. If new columns have been added, they should also be inspected for cleanup. Debug and rematerialize the assets until they load successfully.


As with the extract phase, if new Dagster assets are added to the pipeline, you’ll need to refresh the code location in Dagster by clicking on the circular arrow in the upper left hand corner next to the text “Job in <NAME OF JOB>” before materializing the new assets.

B. FERC Form 1

4.B.1) If you’re mapping FERC tables that have not been included in the ETL yet, look at the src/pudl/package_data/ferc1/dbf_to_xbrl_tables.csv for our preliminary estimation of which DBF tables connect to which XBRL tables. Note that this spreadsheet is not referenced anywhere in the code and should only be used as a reference. Once you’ve verified that these tables are indeed a match, input them into the pudl/extract.ferc1.TABLE_NAME_MAP_FERC1 dictionary for extraction.

4.B.2) For these new tables (or to address changes in xbrl taxonomy), add or update the relationship between DBF rows and XBRL rows in src/pudl/package_data/ferc1/dbf_to_xbrl.csv. See the note below for instructions.


How to use the mapping spreadsheets:

In the Pre-2021 data (from the DBF files), rows are identified by row_number, and the row number that corresponds to a given variable changes from year to year. We cataloged this correspondence, and the connection to the post-2021 data (from XBRL), in src/pudl/package_data/ferc1/dbf_to_xbrl.csv.

The dbf_to_xbrl.csv maps row numbers from the DBF data with taxonomy factoids from the XBRL data therefore allowing us to merge the data into one continuous timeseries. The row_literal column is the DBF label for the row_number in question. This row_literal must be mapped to an xbrl_factoid from the XBRL data. These xbrl_factoid entires are the value columns from the raw XBRL data.

Look at the row_literal values for a given table and see which XBRL columns they coorespond to. It’s helpful to view the XBRL taxonomy for the table in question.

The row_literals may contain elements of the FERC 1 form such as headers that don’t map to an XBRL factoid. These can be marked as headers in the row_type column. Other values are either marked as report_value: a directly reported value in the DBF data, meaning it is not calculated from other values in that table (it may in fact correspond to some calculation derived from values reported in other tables); or a calculated_value: a value which is derived from other values in that table – typically a sum (Total rows) or a net value (credit - debit) of some kind. Often there’s an annotation in the row_literal field that indicates (to humans) what other rows are used to calculate the value. These values will typically also appear in XBRL, with a formula for their calculation reported in the XBRL metadata.

The dbf_only column is marked TRUE if the row_literal only shows up in the DBF files. An common example is when several fields are aggregated in the DBF data but not in XBRL. The notes column is a place to indicate complexity or reasoning and is intended for humans (vs. computers) to read.

4.B.3) Either materialize the clean and/or normalized FERC 1 dagster asset groups or use the FERC 1 debugging notebook devtools/ferc1-etl-debug.ipynb to run the transforms for each table. Heed any errors or warnings that pop up in the logs. One of the most likely bugs will be uncategorized strings (think new, strange fuel type spellings.

4.B.4) If there’s a new column, add it to the transform process. At the very least, you’ll need to include it in the rename_columns dictionary in pudl.transform.params.ferc1.TRANSFORM_PARAMS for the appropriate table.

  • Consider whether the column could benefit from any of the standard transforms in pudl.transform.classes or pudl.transform.ferc1. If so, add them to pudl.transform.params.ferc1.TRANSFORM_PARAMS. Make sure that the parameter you’ve added to TRANSFORM_PARAMS cooresponds to a method that gets called in one of the high-level transform functions in pudl.transform.ferc1.Ferc1AbstractTableTransformer (process_xbrl, process_dbf, transform_start, transform_main) and/or any table-specific overrides in the relevant table transformer class.

  • Consider whether the column could benefit from custom transformations. If it’s something that could be applicable to other tables from other sources, consider building it in pudl.tranform.classes. If it’s specific to FERC1, build it in pudl.transform.ferc1. If it will only ever be relevant to one table in FERC1, build it in the table-specific class in pudl.transform.ferc1, create an override for one of the high-level transform functions, and call it there. Make sure to write a unit test for any new functions.

4.B.5) If there’s a new table, add it to the transform process. You’ll need to build or augment a table transformer in pudl.transform.ferc1 and follow all instructions applicable to new columns.

4.B.6) To see if the transformations work, you can run the transform module as a script in the terminal. From within the pudl repo directory, run:

python src/pudl/transform/ferc1.py


4.C.1) Use dagster to materialize the epacems asset group and debug. The most common errors will occur when new CEMS plants lack timezone data in the EIA database. See section 6.B.1 for instructions on how to fix this. Once you’ve updated the spreadsheet tracking these errors, reload the epacems assets in Dagster.

5. Update the PUDL DB Schema

If new columns or tables have been added, you must also update the PUDL DB schema, define column types, give them meaningful descriptions, apply appropriate ENUM constraints, etc. This happens in the pudl.metadata subpackage. Otherwise when the system tries to write dataframes into SQLite, it will fail or simply exclude any new columns.

5.1) Check whether new columns exist in pudl.metadata.fields.FIELD_METADATA. If they do, make sure the descriptions and data types match. If the descriptions don’t match, you may need to define that column by source: pudl.metadata.fields.FIELD_METADATA_BY_GROUP or by table: pudl.metadata.fields.FIELD_METADATA_BY_RESOURCE. If the column is not in pudl.metadata.fields.FIELD_METADATA, add it.

5.2) Add new columns and tables to the RESOURCE_METADATA dictionaries in the appropriate pudl.metadata.resources modules.

5.3) Update any pudl.metadata.codes, pudl.metadata.labels, or pudl.metadata.enums pertaining to new or existing columns with novel content.

5.4) Differentiate between columns which should be harvested from the transformed dataframes in the normalization and entity resolution process (and associated with a generator, boiler, plant, utility, or balancing authority entity), and those that should remain in the table where they are reported.

5.5) Once you’ve updated the metadata, you’ll need to update the alembic version. See the instructions for doing so in Running the ETL Pipeline. You may have already updated alembic if you used Dagster to materialize the raw and clean assets.

6. Connect Datasets

A. FERC 1 & EIA Plants & Utilities

6.A.1) Run the following command in the terminal, and refer to the PUDL ID Mapping page for further instructions.

$ make unmapped-ids


All FERC 1 respondent IDs and plant names and all EIA plant and utility IDs should end up in the mapping spreadsheet with PUDL plant and utility IDs, but only a small subset of them will end up being linked together with a shared ID. Only EIA plants with a capacity of more than 5 MW and EIA utilities that actually report data in the EIA 923 data tables are considered for linkage to their FERC Form 1 counterparts. All FERC 1 plants and utilities should be linked to their EIA counterparts (there are far fewer of them).

B. Missing EIA Plant Locations from CEMS

6.B.1) If there are any plants that appear in the EPA CEMS dataset that do not appear in the core_eia__entity_plants table, or that are missing latitude and longitude values, you’ll get a warning when you try and materialize the core_epacamd asset group in Dagster. You’ll need to manually compile the missing information and add it to src/pudl/package_data/epacems/additional_epacems_plants.csv to enable accurate adjustment of the EPA CEMS timestamps to UTC. Using the Plant ID from the warning, look up the plant coordinates in the EPA FACT API. In some cases you may need to resort to Google Maps. If no coordinates can be found then at least the plant’s state should be included so that an approximate timezone can be inferred.

7. Run the ETL

Once the FERC 1 and EIA utilities and plants have been associated with each other, you can try and run the ETL with all datasets included. See: Running the ETL Pipeline.

7.1) First run the ETL for just the new year of data, using the etl_fast.yml settings file.

7.2) Once the fast ETL works, run the full ETL using the etl_full.yml settings to populate complete FERC 1 & PUDL DBs and EPA CEMS Parquet files.

8. Update the Output Routines and Run Full Tests

8.1) With a full PUDL DB, update the denormalized table outputs and derived analytical routines to accommodate the new data if necessary. These are generally called from within the pudl.output.pudltabl.PudlTabl class.

  • Are there new columns that should incorporated into the output tables?

  • Are there new tables that need to have an output function defined for them?

8.2) To ensure that you fully exercise all of the possible output functions, run all the integration tests against your live PUDL DB with:

$ make pytest-integration-full

9. Run and Update Data Validations

9.1) When the CI tests are passing against all years of data, sanity check the data in the database and the derived outputs by running

$ make pytest-validate

We expect at least some of the validation tests to fail initially because we haven’t updated the number of records we expect to see in each table.

9.2) You may also need to update the expected distribution of fuel prices if they were particularly high or low in the new year of data. Other values like expected heat content per unit of fuel should be relatively stable. If the required adjustments are large, or there are other types of validations failing, they should be investigated.

9.3) Update the expected number of rows in the minmax_row validation tests. Pay attention to how far off of previous expectations the new tables are. E.g. if there are already 20 years of data, and you’re integrating 1 new year of data, probably the number of rows in the tables should be increasing by around 5% (since 1/20 = 0.05).

10. Update the Documentation

10.1) Once the new year of data is integrated, update the documentation to reflect the new state of affairs. This will include updating at least:

Check that the docs still build with

$ make docs-build