The Eastern Interconnection model is an hourly zonal production cost model covering four interconnected ISOs: NYISO, PJM, ISO-NE, and MISO. It simulates wholesale electricity market outcomes (prices, dispatch, flows, and emissions) from 2026 through 2050.
Each ISO is represented at the zonal level using EIA-930 balancing authority boundaries, with ISO-specific load forecasting, market design, and capacity mechanisms. The market designs are compared below and detailed on each topic page.
Coverage
- NYISO: 11 load zones (A through K)
- MISO: 10 Local Resource Zones (LRZ1 to LRZ10), split into North/Central and South subregions
- PJM: 20 transmission zones, with Locational Deliverability Areas (LDAs) for capacity
- ISO-NE: planned
Footprint-wide inputs that span all ISOs are documented once: Commodity Prices and Emissions & Policy.
Inputs
| Category | Summary | Key Data Sources | Scope |
|---|---|---|---|
| Demand | Zonal hourly load forecasts, built per ISO from its primary forecast source | EIA-930, ISO load forecasts | Per ISO |
| Generation | Plant-level inventory, heat rates, stepped bid curves, and capacity factor profiles | EIA-860, EIA-923 | Per ISO |
| Commodity prices | Zonal natural gas by pipeline hub, coal by basin, distillate fuel oil | CME NG Futures, EIA AEO, daily spot data | Shared |
| Transmission | Zonal interface limits, HVDC interconnections, directional wheeling charges | EIA-930, ISO operating studies | Per ISO |
| Emissions & policy | RGGI CO2 budget, federal tax credits | RGGI, NREL ATB | Shared |
| Capacity expansion | Forward capacity buildout from CEM; IC queue projections for near-term | NREL ATB, ISO interconnection queues | Per ISO |
Modeling
Two-stage unit commitment and dispatch
The model runs in two stages per day. The unit commitment stage determines which thermal generators are online using binary on/off variables and MIP solving. The economic dispatch stage fixes those commitment decisions and re-optimizes generation output as a pure LP, yielding locational marginal prices from shadow prices on the power balance constraint.
Separate wheeling hurdle rates are applied at each stage: commitment hurdle rates in UC, dispatch hurdle rates in redispatch, reflecting the difference between scheduling and real-time congestion signals.
Operating reserves
Operating reserves ensure sufficient spare generation capacity is available to respond to unexpected outages or demand spikes. The model enforces a minimum reserve requirement at each node, based on a percentage of load. When available reserves fall short, a reserve penalty price is added to locational prices, reflecting the increased cost of maintaining reliability.
Emissions
RGGI applies a regional CO2 budget to generators in member states. See Emissions & Policy for cap schedules and which ISOs are affected.
Ancillary services
Ancillary services are valued post-solve, not co-optimized with energy. See the Dispatch Model for the products modeled by ISO and how revenues are applied.
Outputs
Macro databook
Annual system-level metrics compiled from hourly solve outputs:
- Generation by technology: system-wide and per-ISO splits
- Zonal prices: annual average, TB4 and TB2 top-bottom spreads (price volatility)
- Peak demand: summer and winter by zone
- Emissions: total CO2 and carbon price shadow values
- Capacity prices: clearing prices by each ISO’s capacity mechanism
Site-specific databook
Monthly and annual BESS metrics for individual storage assets:
- Revenue: energy arbitrage and ancillary services
- Cycling: charge/discharge cycles and degradation
- Capacity factors: utilization by market product
Dispatch model revenues
The dispatch model produces site-specific revenue forecasts broken down by stream: energy arbitrage, ancillary services, capacity market payments, and any ISO-specific storage subsidy. Revenue stream composition is ISO-specific, summarized in the comparison below.
Market design by ISO
Each ISO runs a different market design. The headline features are compared below; follow the topic links for full methodology.
| Feature | NYISO | MISO | PJM |
|---|---|---|---|
| Demand | Five-segment bottom-up, NYISO Gold Book | LRZ-level, MISO Long-Term Load Forecast | Zonal, PJM Load Forecast Report |
| Capacity market | ICAP demand curve, four nested localities | Seasonal Planning Resource Auction, Reserve-Based Demand Curve | RPM Base Residual Auction, VRR curve nested by LDA |
| Accreditation | Capacity Accreditation Factor (CAF) | Schedule 53 UCAP, moving to Direct Loss-of-Load (DLoL) | Effective Load Carrying Capability (ELCC) |
| Ancillary services | 10-min spinning, 10-min non-sync, 30-min operating, regulation | Regulation, spinning, supplemental | Regulation, synchronized and primary reserve |
| Storage subsidy | Indexed Storage Credit (ISC) | None | None |
| Carbon (RGGI) | Member state | Not a RGGI region | NJ, MD, DE, and VA portions only |
Per-ISO detail lives on the Demand, Capacity Prices, Dispatch Model, and Emissions & Policy pages.