Update natural gas regression parameters (betas and alphas) with AEO 2026 (2025 -> 2026)

[Yunzhi-Chen]

Summary

Updates the natural gas (NG) supply curve regression parameters (betas and alphas) from AEO 2025 to AEO 2026, using the demeaned fixed-effects OLS pipeline described in ReEDS_Input_Processing PR #3. Also adds new AEO 2026 input files (prices, demands, alphas) and the 2025$ deflator.

Technical details

Beta regression (Stage 1): Re-estimated 9 regional betas and 1 national beta from AEO 2026 scenarios using demeaned fixed-effects OLS. Key updated values in cd_beta0.csv (AEO 2025 -> AEO 2026):

• New_England: 3.875 -> 2.359
• Mid_Atlantic: 0.151 -> 0.185
• East_North_Central: 0.033 -> 0.013
• West_North_Central: 0.857 -> 0.513
• South_Atlantic: 0.175 -> 0.030
• East_South_Central: 0.140 -> -0.026
• West_South_Central: -0.055 -> -0.127
• Mountain: 0.670 -> 0.050
• Pacific: 1.342 -> 0.705

nat_beta_nonenergy in scalars.csv: 0.080017 -> 0.078702

Alpha regression (Stage 2): Recalculated alpha intercepts for Reference, HOG, and LOG cases using the new betas and AEO 2026 price/demand data.

Implementation notes

• 12 new files added under inputs/fuelprices/: alpha_AEO_2026_*.csv, ng_AEO_2026_*.csv, ng_demand_AEO_2026_*.csv, ng_tot_demand_AEO_2026_*.csv for HOG, LOG, and Reference cases
• inputs/financials/deflator.csv: added 2025 deflator (0.586750)
• inputs/fuelprices/dollaryear.csv: added AEO_2026_HOG/LOG/reference entries with 2025 dollar year

Relevant sources or documentation

• Source data: EIA Annual Energy Outlook 2026

Validation, testing, and comparison report(s)

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 (Claude) to assist with updating the model documentation text (equations, methodology description) and drafting the PR description.

[wesleyjcole]

You can remove the AEO2023 values.

[wesleyjcole]

There is not a reference scenario in AEO2026. Would you change the name to "AEO_2026_baseline" for inputs from their Counterfactual Baseline scenario?