UAMPS warns centralized day‑ahead market will change how Hurricane procures and operates power

UAMPS staff told Hurricane city leaders on Oct. 31 that a centralized extended day‑ahead market (EDAM) operated across CAISO and PacifiCorp will begin in May 2026 and materially change how the city buys and schedules wholesale power.

The shift moves wholesale trading from a bilateral, phone‑or‑contract model to a centralized, software‑driven market that requires each load‑serving entity to show day‑ahead resource sufficiency (RSE) and submit resource offers and bids. "Instead of throughout the day making phone calls and bilateral purchases, on a day‑ahead basis we'll look at what the load is and procure remaining need for the closing day," said Matt, UAMPS market lead.

Why it matters: Under EDAM the market operator lines up all available resources across a broad footprint and dispatches them based on bid curves and transmission constraints. That means a locally owned plant that previously was used selectively may be dispatched (and paid) by the market when economically chosen, or may be left idle if lower‑cost resources clear the market. UAMPS cautioned that the transition could produce "bumps" and pricing volatility early on, citing prior experience when the energy imbalance market matured.

How EDAM works in practice: UAMPS staff said each day, by 9 a.m., Hurricane must show it has resources to meet its day‑ahead hourly requirement. PacifiCorp will calculate a balancing‑area RSE and allocate portions to load‑serving entities based on a three‑year look‑back. UAMPS will in turn allocate that obligation to members. Matt said the design intends to lower overall costs by dispatching the lowest‑cost resources across the footprint, but acknowledged it cannot guarantee prices will fall for every member.

Local control and scheduling choices: Hurricane retains control over which resources it offers into the market and whether to self‑schedule certain assets. UAMPS staff described three categories of member generation: (1) generators already in CAISO’s full network model (which must either self‑schedule or bid into the market), (2) generators not yet in the full model but charged transmission, and (3) generators not in the full model and not charged transmission (where Hurricane currently sits). "If you stay out of the full network model, then the load looks like it's just 50 megawatts because it's already being subtracted for internal generation," Matt said.

Near‑term risks and mitigations: Staff urged members to prepare for daily 7‑day workstreams (day‑ahead purchasing will be a seven‑day activity) and said parallel settlements and test runs will start in January before full go‑live. UAMPS has committed to participate actively in the stakeholder process and to seek tariff revisions with FERC and the market operator if congestion or allocation rules create unintended consequences.

Quote: "There will be bumps along the way as the market begins," Matt said. "We saw that with the energy imbalance market." The presentation included specific operational changes staff will bring back to councils for approval, including amendments to the pool agreement to give UAMPS authority to secure RSE resources on members' behalf.

What comes next: Staff said they will run comparison reports beginning in January to estimate member impacts and will provide draft contract language and allocation models to councils before May, when EDAM goes live.