This blog post describes a Frictionless Data Pilot with the Public Utility Data Liberation project. Pilot projects are part of the Frictionless Data for Reproducible Research project. Written by Zane Selvans, Christina Gosnell, and Lilly Winfree.

The Public Utility Data Liberation project, PUDL, aims to make US energy data easier to access and use. Much of this data, including information about the cost of electricity, how much fuel is being burned, powerplant usage, and emissions, is not well documented or is in difficult to use formats. Last year, PUDL joined forces with the Frictionless Data for Reproducible Research team as a Pilot project to release this public utility data. PUDL takes the original spreadsheets, CSV files, and databases and turns them into unified Frictionless tabular data packages that can be used to populate a database, or read in directly with Python, R, Microsoft Access, and many other tools. 

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What is PUDL?

The PUDL project, which is coordinated by Catalyst Cooperative, is focused on creating an energy utility data product that can serve a wide range of users. PUDL was inspired to make this data more accessible because the current US utility data ecosystem fragmented, and commercial products are expensive. There are hundreds of gigabytes of information available from government agencies, but they are often difficult to work with, and different sources can be hard to combine.

PUDL users include researchers, activists, journalists, and policy makers. They have a wide range of technical backgrounds, from grassroots organizers who might only feel comfortable with spreadsheets, to PhDs with cloud computing resources, so it was important to provide data that would work for all users. 

Before PUDL, much of this data was freely available to download from various sources, but it was typically messy and not well documented. This led to a lack of uniformity and reproducibility amongst projects that were using this data. The users were scraping the data together in their own way, making it hard to compare analyses or understand outcomes. Therefore, one of the goals for PUDL was to minimize these duplicated efforts, and enable the creation of lasting, cumulative outputs.

What were the main Pilot goals?

The main focus of this Pilot was to create a way to openly share the utility data in a reproducible way that would be understandable to PUDL’s many potential users. The first change Catalyst identified they wanted to make during the Pilot was with their data storage medium. PUDL was previously creating a Postgresql database as the main data output. However many users,  even those with technical experience, found setting up the separate database software a major hurdle that prevented them from accessing and using the processed data. They also desired a static, archivable, platform-independent format. Therefore, Catalyst decided to transition PUDL away from PostgreSQL, and instead try Frictionless Tabular Data Packages. They also wanted a way to share the processed data without needing to commit to long-term maintenance and curation, meaning they needed the outputs to continue being useful to users even if they only had minimal resources to dedicate to the maintenance and updates. The team decided to package their data into Tabular Data Packages and identified Zenodo as a good option for openly hosting that packaged data.

Catalyst also recognized that most users only want to download the outputs and use them directly, and did not care about reproducing the data processing pipeline themselves, but it was still important to provide the processing pipeline code publicly to support transparency and reproducibility. Therefore, in this Pilot, they focused on transitioning their existing ETL pipeline from outputting a PostgreSQL database, that was defined using SQLAlchemy, to outputting datapackages which could then be archived publicly on Zenodo. Importantly, they needed this pipeline to maintain the metadata, information about data type, and database structural information that had already been accumulated. This rich metadata needed to be stored alongside the data itself, so future users could understand where the data came from and understand its meaning. The Catalyst team used Tabular Data Packages to record and store this metadata (see the code here:

Another complicating factor is that many of the PUDL datasets are fairly entangled with each other. The PUDL team ideally wanted users to be able to pick and choose which datasets they actually wanted to download and use without requiring them to download it all (currently about 100GB of data when uncompressed). However, they were worried that if single datasets were downloaded, the users might miss that some of the datasets were meant to be used together. So, the PUDL team created information, which they call “glue”,  that shows which datasets are linked together and that should ideally be used in tandem. 

The cumulation of this Pilot was a release of the PUDL data (access it here – and read the corresponding documentation here –, which includes integrated data from the EIA Form 860, EIA Form 923, The EPA Continuous Emissions Monitoring System (CEMS), The EPA Integrated Planning Model (IPM), and FERC Form 1.

What problems were encountered during this Pilot?

One issue that the group encountered during the Pilot was that the data types available in Postgres are substantially richer than those natively in the Tabular Data Package standard. However, this issue is an endemic problem of wanting to work with several different platforms, and so the team compromised and worked with the least common denominator.  In the future, PUDL might store several different sets of data types for use in different contexts, for example, one for freezing the data out into data packages, one for SQLite, and one for Pandas. 

Another problem encountered during the Pilot resulted from testing the limits of the draft Tabular Data Package specifications. There were aspects of the specifications that the Catalyst team assumed were fully implemented in the reference (Python) implementation of the Frictionless toolset, but were in fact still works in progress. This work led the Frictionless team to start a documentation improvement project, including a revision of the specifications website to incorporate this feedback. 

Through the pilot, the teams worked to implement new Frictionless features, including the specification of composite primary keys and foreign key references that point to external data packages. Other new Frictionless functionality that was created with this Pilot included partitioning of large resources into resource groups in which all resources use identical table schemas, and adding gzip compression of resources. The Pilot also focused on implementing more complete validation through goodtables, including bytes/hash checks, foreign keys checks, and primary keys checks, though there is still more work to be done here.

Future Directions

A common problem with using publicly available energy data is that the federal agencies creating the data do not use version control or maintain change logs for the data they publish, but they do frequently go back years after the fact to revise or alter previously published data — with no notification. To combat this problem, Catalyst is using data packages to encapsulate the raw inputs to the ETL process. They are setting up a process which will periodically check to see if the federal agencies’ posted data has been updated or changed, create an archive, and upload it to Zenodo. They will also store metadata in non-tabular data packages, indicating which information is stored in each file (year, state, month, etc.) so that there can be a uniform process of querying those raw input data packages. This will mean the raw inputs won’t have to be archived alongside every data release. Instead one can simply refer to these other versioned archives of the inputs. Catalyst hopes these version controlled raw archives will also be useful to other researchers.

Another next step for Catalyst will be to make the ETL and new dataset integration more modular to hopefully make it easier for others to integrate new datasets. For instance, they are planning on integrating the EIA 861 and the ISO/RTO LMP data next. Other future plans include simplifying metadata storage, using Docker to containerize the ETL process for better reproducibility, and setting up a Pangeo  instance for live interactive data access without requiring anyone to download any data at all. The team would also like to build visualizations that sit on top of the database, making an interactive, regularly updated map of US coal plants and their operating costs, compared to new renewable energy in the same area. They would also like to visualize power plant operational attributes from EPA CEMS (e.g., ramp rates, min/max operating loads, relationship between load factor and heat rate, marginal additional fuel required for a startup event…). 

Have you used PUDL? The team would love to hear feedback from users of the published data so that they can understand how to improve it, based on real user experiences. If you are integrating other US energy/electricity data of interest, please talk to the PUDL team about whether they might want to integrate it into PUDL to help ensure that it’s all more standardized and can be maintained long term. Also let them know what other datasets you would find useful (E.g. FERC EQR, FERC 714, PHMSA Pipelines, MSHA mines…).  If you have questions, please ask them on GitHub ( so that the answers will be public for others to find as well.

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Lilly is the Product Manager for the Frictionless Data for Reproducible Research project. She has her PhD in neuroscience from Oregon Health and Science University, where she researched brain injury in fruit flies and became an advocate for open science and open data. Lilly believes that the future of research is open, and is using Frictionless Data tooling within the researcher community to make science more reproducible.