Planned U.S. power plants missing from EIA's January list arrive by August, and the reason is still open

Description and use

Planned U.S. power plants missing from the January EIA‑860M list typically appear by August, with an even distribution from February to August and 99% of capacity captured by August.

Problem

Some generators planned in the annual EIA-860 survey are missing from the monthly EIA-860M January list, creating uncertainty about when they appear in the monthly data.

Outcome

The study confirms that plants missing from the January monthly list typically appear by August, with an even distribution of appearance from February to August and a 99% capture rate by August.

Workflow

• 1. Pre-register a test to determine when missing plants first appear in the monthly survey.
• 2. Run the test on data from 2018‑2025 using PUDL copies of both surveys.
• 3. Analyze the share of capacity first listed in each monthly period (Feb‑Dec).
• 4. Observe that 56% of capacity appears in March‑June reports and about 1% in Oct‑Dec reports.
• 5. Note that new plants not in the annual plan appear in March‑June at 5% share.
• 6. Determine that entry is even from February to August, with 57% of February‑August capacity listed by March‑June.
• 7. Conclude that 99% of capacity is in by the August report.
• 8. Identify that the August report aligns with the final version of the annual file, suggesting a lag in monthly updates.
• 9. Provide code, data, and pre‑registration details on GitHub.

Evidence

Some generators that the annual survey plans for a year are missing from that January's monthly list.

Source

All five predictions held (shares are of the capacity first listed in the February-December reports).

Source

Entry is about even from the February report to the August report (March-June holds 57% of the February-August capacity, close to what an even spread gives), and 99% of the capacity is in by the August report.

Source

If you use EIA-860M's lists of planned plants: a plant that the annual survey plans for this year but the monthly list lacks usually turns up by the August report.

Source