Supply & Demand

What exists, what was bought, what PJM assumed, and what demand requires, for the last four capacity auctions. PJM keeps two different lists of power plants; this tab keeps them straight. Static tab: nothing here moves the other tabs.

ICAP vs UCAP: two counts of the same fleet

UCAP is the market's currency: the credit the auction buys, built unit by unit from data only PJM holds. ICAP (installed capacity) is the nameplate fleet the engine dispatches: real machines facing real weather. The wedge between them is the accreditation haircut, and it is where this project's argument lives: reliability comes from the machines, payment follows the credit.

The reconstruction pins the UCAP total to the procured book exactly. Nameplate derives class by class, so the mix, not the total, carries the model risk.

What RRS is

The Reserve Requirement Study (RRS) is PJM's annual study setting how much capacity the system needs to hit 0.1 loss-of-load days per year. The assumed fleet above is an RRS-style deck, and the requirement diamonds trace to it.

Two books kept straight: the committed fleet beside the assumed fleet, in UCAP, with demand as the published input.

What's in it

PJM does not publish resource-specific award quantities, so the committed fleet's class detail is either PJM's own published fuel rows (plan basis, where a year has them) or a labelled model reconstruction, never an unlabelled blend.

How we do it

  1. 1.Anchor the committed book. Cleared plus self-supply per year, verified against PJM's auction reports to the decimal.
  2. 2.Convert the assumed book. PJM's published assumed mix per year times PJM's own posted class ratings gives the UCAP-equivalent markers.
  3. 3.State demand as input. PJM's forecast peaks and published requirements per auction; the forward view splices the published requirement onto the 2026-vintage forecast.
Full methodology
supply-demand.json (per-year books, demand and the shortfall split, from the dated carriers), portfolio.json (committed-fleet reconstruction deep dive), auctions.json (cleared cells cross-check).

Source: PJM published 2028/29 planning parameters and posted ELCC ratings, reconstructed and verified by SemiAnalysis | Last updated: August 2026