Index-variability

This repository contains the data analysis and figure generation code for Assessing the evolution of power sector carbon intensity in the United States, 2018, Environmental Research Letters, DOI:10.1088/1748-9326/aabe9d. The methods and code borrow heavily from the Power Sector Carbon Index (EmissionsIndex.org).

Links to download data

The links below take you to folders with final data from the paper.

• National data
• NERC region data
• State data

Or you can download individual csv files with these links (you may need to right-click and "Save As"):

• National
  • Carbon intensity
  • Generation by fuel category
• NERC regions
  • Carbon intensity
  • Generation by fuel category
• State
  • Carbon intensity
  • Generation by fuel category

Have trouble? Submit an issue

I have tried to set this code up so that it is easy to understand and run, but there may be errors or confusing parts. If you find a bug, have a question, or want to suggest a change, please submit an issue.

Organization

Most analysis is done with a series of Jupyter notebooks in the Notebooks folder. Commonly used functions are included as scripts in the src folder. Most necessary data is downloaded automatically with scripts, but you will need to download and extract EIA's bulk electricity data file (or use this direct link: ELEC.zip). We use EIA's bulk data file rather than the EIA-923 Excel files because it is an easy way to access all of the generation and fuel consumption data in one place. The datafile also includes lat/lon data for each plant, which would otherwise have to be accessed through EIA-860.

Data files are located in the Data storage folder. Some files aren't included in this repo - they either need to be downloaded manually (e.g. the ELEC.txt file) or using code in one of the notebooks (e.g. EPA emissions data).

Recreating results

Producing monthly generation by fuel type, adjusted fossil CO₂ emissions, and CO₂ intensity at state, regional, and national levels is not yet fully automated. As mentioned above, a few data files need to be obtained or created manually. Otherwise, follow the steps below. Most notebooks can be run in their entirety (click "Cell" --> "Run All"), but some will require changing parameter values or file names. Notebooks can also be exported as .py files and run as individual scripts. Running in notebook form makes it easier to examine the data as they are processed through the pipeline.

Installing Python and setting up environment

I recommend installing Python 3 with Anaconda (or use Miniconda for a smaller install). Once you have conda installed and have cloned this repository, use the provided environment.yml file to create a conda environment. The environment name provided is psci (power sector carbon index).

Download and extract EPA emissions

1. Run the Download EPA emissions data notebook. This will download zip files for selected years from the AMPD ftp server, extract the hourly data, change column names to make them consistent over time, and combine everything into .csv files for each year. These files are quite large (~4GB per year). Use the provided option to export as a .feather file to speed up file reads and writes.
2. Run the Group EPA emissions data by month notebook. This will read in the .csv (or .feather) files that were just created, group emissions for each facility to the monthly level, and export a single .csv file.

Code for these two notebooks could be combined without too much trouble, skipping the step of writting large files to disk.

Extract data from EIA bulk file

1. Run the EIA Bulk Download - extract facility generation notebook. This reads in data from ELEC.txt, extracts generation and fuel consumption data, calculates CO₂ emissions from the fuel consumption using emission factors, and exports the results as a .csv file.
2. Run the EIA bulk download - non-facility (distributed PV & state-level) notebook. This reads in the ELEC.txt file again, but extracts state-level total generation and fuel consumption. As above, calculate CO₂ emissions using emission factors. Export both national and state-level results to .csv files.

Assign NERC labels to power plants

1. Run the Assign NERC region labels notebook. This requires first downloading EIA-860 Excel files. For analysis through 2017 I have downloaded all annual files from 2011 through 2016. These Excel files list the NERC region that each power plant is assigned to. The notebook determines NERC regions for plants that stopped operating before 2011, or came online after 2016, using k-nearest neighbors with lat/lon data as the input features. NERC regions are not strictly defined by their location, so a strict spatial delineation (or a spatial join) is not possible.

Calculate generation by fuel, total CO₂, and CO₂ intensity

1. For national and NERC regions, run the Calculate national and NERC gen and emissions notebook. This reads in facility data, EIA state-level data (at national level), EPA emissions, and emission factors. It calculates the historical fraction of generation/fuel consumption from annual reporting facilities in each NERC region within a states, and uses the results to allocate state-level estimates in recent years to NERC regions. We have to do this because a subset of power plants only have to report EIA-923 at the end of the year. EIA estimates their generation/fuel consumption throughout the year, reporting it as part of the state-level totals. Actual facility data is included in the final 923 release the following fall. Note This notebook produces final national results, but only extra generation/fuel consumption for NERC regions.
2. Since the notebook above doesn't actually calculate final NERC results, open up the Calculate NERC results notebook (these should probably be combined at some point). Start by loading in the extra gen/fuel consumption calculated above, and calculate CO₂ emissions using emission factors. Facility data are grouped into NERC regions, and combined with the extra data to create total generation (including by fuel) and emissions.
3. Finally, run the Compile state index & gen files notebook.

Calculate monthly operable capacity

1. Run the Capacity notebook.

Generate figures and top-line numbers

1. For NERC and national figures, run the Paper figures notebook.
2. For state-level barbell and SI figures, run the State figures notebook.
3. For the NERC maps in Figure 2, run the NERC maps notebook.