Update natural gas regression parameters (betas and alphas) with AEO 2025 (old -> 2025)

[Yunzhi-Chen]

Summary

Update the natural gas price regression parameters (regional betas, national beta, and scenario-specific alphas) from old AEO 2018-era coefficients to newly regressed AEO 2025 values. The regression pipeline and detailed methodology are documented in ReEDS_Input_Processing PR #2. This is a data-only PR — 14 CSV files updated under inputs/fuelprices/ plus one scalar in inputs/scalars.csv.

Files changed:

• cd_beta0.csv — regional betas (re-estimated from AEO 2025)
• scalars.csv — nat_beta_nonenergy updated (0.1352 → 0.080017)
• alpha_AEO_2025_{reference,HOG,LOG}.csv — alphas recomputed for three scenarios
• ng_AEO_2025_{reference,HOG,LOG}.csv — NG prices
• ng_demand_AEO_2025_{reference,HOG,LOG}.csv — electric-sector NG demand
• ng_tot_demand_AEO_2025_{reference,HOG,LOG}.csv — total NG demand

Technical details

See ReEDS_Input_Processing PR #2 for full regression methodology, pipeline code, and diagnostic plots.

Note: Some rows in the demand CSV files show diff changes that are purely formatting (trailing zeros added, e.g., 0.26856 → 0.268560). These do not affect numeric values.

Issues resolved

Resolves #30 — Update gas price elasticities.

Relevant sources or documentation

• ReEDS_Input_Processing PR #2
• EIA AEO 2025

Validation, testing, and comparison report(s)

Three ReEDS runs were performed with old vs. new parameters to compare capacity expansion results:

1. Reference case

2. High NG demand case: High electricity demand growth + conservative ATB projections for renewable energy technologies (intended to create a scenario where natural gas demand is much higher to understand the impact of the elasticities).

3. Low NG demand case: Enforces net-zero emissions by 2035 (intended to create a scenario where natural gas demand is very low to understand the impact of the elasticities).

Capacity expansion results comparison

NG price elasticity update -2025.pptx

Checklist for author

Details to double-check

• Charge code provided for review
• Included comparison reports for appropriate test cases
• Documentation updated if necessary
• If input data added/modified:
  • Dollar year recorded and converted to 2004$ for GAMS
  • Timeseries are in Central Time
  • Units are specified
  • Preprocessing steps have been documented and committed to ReEDS_Input_Processing
  • New large data files handled with .h5 instead of .csv
  • If spatially resolved inputs are modified, the following visualizations for each file are included in the PR description (time-averaged if the inputs are time-resolved):
    • Map of absolute values before
    • Map of absolute values after
    • Map of differences: (after - before) or (after / before)
• Code formatting standardized
• Reusable functions used where possible instead of copy/pasted code

General information to guide review

• Zero impact on results of default case
• No large data file(s) added/modified
• No substantive impact on runtime for full-US reference case
• No substantive impact on folder size for full-US reference case
• No change to process flow (runbatch.py, d_solve_iterate.py)
• No change to code organization
• No change to package requirements (environment.yml or Project.toml)

Did you use LLM tools (chatbot or copilot) in the preparation of this PR? If so, describe how

Yes — used GitHub Copilot to assist with drafting the PR description.

Tag points of contact here if you would like additional review of the relevant parts of the model

• Financial calculations / fuel prices: @wcole

[wesleyjcole]

We typically only keep the current AEO and last AEO in ReEDS, so you can delete the AEO2023 inputs for the natural gas files you are updating.

[wesleyjcole]

This looks good. Just a few minor comments.

Would you add a screenshot of the reference case capacity or generation difference to the PR text so that people can easily see at least one view of the impacts without needing to find it in the slide deck?

Also - I noted last time that we don't need to keep the AEO2023 files. I confused that with the AEO 2026 update. I don't think that will be an issue given that you already have a AEO2026 pull request put together--I just wanted to flag my confusion in hopes that it won't complicate future updates.