ON · Hybrid / administered market · 2023
A nuclear-refurbishment system with gas as swing. The IESO 2026 APO says energy grows 65% by 2050 and the next capacity hole is mid-2030s, not tomorrow. Darlington SMR Unit 1 is under construction.
| 2023 | 2026 | 2030 | 2035 | 2050 | |
|---|---|---|---|---|---|
| Generation TWh | 158.1 | 151.7 | 155.3 | 173.2 | 225.5 |
| End-use electricity TWh | 138.5 | 137.6 | 149.3 | 167.3 | 218.1 |
| Capacity GW | 43.4 | 45.0 | 46.9 | 48.4 | 73.2 |
| Gen − end-use TWh | 19.7 | 14.1 | 6.0 | 6.0 | 7.5 |
Same workbook for every jurisdiction. Residual ≠ surplus. Source: CER EF2026.
The IESO’s March 2026 Annual Planning Outlook is the dossier forecast. Net energy demand: 152 TWh in 2026, 250 TWh in 2050 (+65% reference). High case 297 TWh (+92%); low case 207 TWh (+38%). Near-term CAGR is 3.0% (2026–30). Data centres are 8.6% of 2050 demand. Efficiency and DSM cut 8% off 2050 energy — Toronto’s current annual use. Grid-level demand has already been rising from the old 132–146 TWh band. Per-capita use is still below the national average because space heat is mostly gas. Dual-peaking arrives in the late 2030s in the reference case. The federal EV sales mandate was repealed in February 2026; IESO will fully recast that in the 2027 APO.
Summer-peaking historically; winter peak is rising with heat pumps. Data centres and industrial electrification are the new adequacy problem.
Regulated Price Plan (TOU, tiered, ultra-low overnight) plus delivery, regulatory charges, Global Adjustment, and the Ontario Electricity Rebate. Mid-pack nationally; not Quebec, not Alberta.
IESO: 2026 Annual Planning Outlook (2026-03-20)
Ontario is adequate into the early 2030s after storage and gas procurements. The next capacity hole is mid-2030s as gas contracts expire and demand keeps rising. Installed capacity ~39 GW at end-2026 (nuclear 8.5, gas/oil 11.4, hydro 9.3, wind 5.5, solar 2.6, storage 1.2). Summer effective capacity is 26–29 GW in the late 2020s — nameplate is not peak capability. Dual-peaking arrives in the late 2030s in the reference case. Data centres are 8.6% of 2050 demand. Efficiency knocks 8% off 2050 demand, about Toronto’s current annual use.
Net annual energy demand (includes embedded). Not the same as CER end-use electricity. Installed capacity is IESO-visible resources; effective capacity is lower. Primary document
IESO-visible installed capacity is about 39 GW at end-2026: gas/oil 11.4, hydro 9.3, nuclear 8.5 (units on refurbishment excluded), wind 5.5, solar 2.6, storage 1.2. Summer effective capacity is 26–29 GW — a third of nameplate does not show up on a hot afternoon. Pickering A retired at the end of 2024. Darlington Unit 4 returned from refurbishment on 2 February 2026, early. IESO’s schedule has Darlington refurbishments done in 2026, Bruce in 2033, Pickering B in 2034; 500–3,700 MW of nuclear is offline each summer until then. Darlington SMR Unit 1 (300 MW BWRX-300) is under construction — foundation hold point cleared 30 March 2026. Units 2–4 and new large nuclear at Bruce are still announced.
Hydro One owns almost all bulk transmission. Interties: Ontario–US (NYISO) 2,300 MW out / 2,105 MW in; Ontario–US (MISO) 1,650 / 1,795 MW; Ontario–Quebec 1,970 MW both ways; Ontario–Manitoba ~250 MW (NRCan 2026). Most imports historically come from Quebec; most exports go to New York and Michigan. That is the national pattern in miniature: more north–south than east–west.
| Path | MW → | MW ← | Kind |
|---|---|---|---|
| Manitoba – Ontario | 260 | 250 | interprovincial |
| Ontario – US (MISO) | 1,650 | 1,795 | international |
| Ontario – US (NYISO) | 2,300 | 2,105 | international |
| Ontario – Quebec | 1,970 | 1,970 | interprovincial |
Transfer capability, not average flows. Source: NRCan Powering Canada Strong, May 2026, Figure 5.
Ontario restructured in 2002, then partially retreated. Generation competes; the IESO runs the wholesale market and resource adequacy procurements (including the largest storage procurement in the country). Most households stay on OEB-regulated prices. The Global Adjustment is where the cost of contracts, nuclear, and conservation actually lands. Retail choice exists but is a rounding error.
Ministry of Energy and Electrification sets policy and owns the IESO/OEB relationship. OEB regulates rates and wires. IESO operates the grid and procures. OPG is the generating Crown. Bruce Power is a private operator of Crown-owned units. CNSC licenses the nuclear fleet. CER permits international lines.
| Operator | Independent Electricity System Operator (IESO) |
| Regulator | Ontario Energy Board |
| Transmission | Hydro One (≈ 30,000 km); smaller transmitters exist |
| Dominant utility | Ontario Power Generation (Crown) + Bruce Power |
OPG (hydro, nuclear, biomass). Bruce Power (nuclear). Hydro One (wires). Independents: Brookfield, TransAlta, Northland, Innergex, Capital Power, Pattern. Municipal distributors: Toronto Hydro, Hydro Ottawa, Alectra. Storage: Northland Oneida (250 MW, in service 2025) plus a 739 MW battery cohort.
Operating: Oneida and the rest of a ~1.2 GW storage stack by end-2026; Darlington Unit 4 back. Under construction: remaining Bruce/Pickering B refurbs; Darlington SMR Unit 1. In-flight procurements (not in the IESO committed supply stack): LT2 windows, Long Lead-Time RFP (800 MW / 2035), Local Generation Program (~2,000 MW of expiring contracts). Announced: SMR units 2–4, new large nuclear at Bruce. Incremental needs after committed supply: 8.5 TWh energy by 2032; <100 MW capacity in 2034, 950 MW in 2035, 3,800 MW / 37 TWh by 2040.
| Plant | Fuel | MW | Status | Owner |
|---|---|---|---|---|
| Bruce NGS | nuclear | 6,232 | operating | Bruce Power / OPG assets |
| Darlington NGS | nuclear | 3,500 | operating | OPG |
| Pickering NGS B | nuclear | 2,064 | operating | OPG |
| Atikokan GS | biomass | 205 | operating | OPG |
| Oneida Energy Storage | storage | 250 | operating | Northland Power |
| Darlington SMR Unit 1 | nuclear | 300 | under construction | OPG |
| Darlington SMR Units 2–4 | nuclear | 900 | announced | OPG |
Who pays for the next increment — Global Adjustment, ITCs/CIB, or industrial customers. Gas as the 2030s reliability fleet versus federal Clean Electricity Regulations (IESO explicitly does not model CER as written; it models a near-zero-by-2050 gas path that keeps the units available). Data-centre queues versus residential rates. Pickering B refurb cost versus close.
| Metric | 2023 | Note |
|---|---|---|
| Generation | 158.14 TWh | CER EF2026 |
| Capacity | 43,355.6 MW | includes storage where reported |
| End-use electricity | 138.5 TWh | converted from PJ |
| Net international exports | +14.8 TWh net export | positive = export |
| Interprovincial in-flows | 4.3 TWh | Quebec’s in-flow is mostly Churchill Falls |