Transmission-Connected Generation

Transmission-connected generation refers to facilities that are connected to the high-voltage IESO-Controlled Grid, which include all lines over 50 kilovolts (kV), such as 115 kV, 230 kV, and 500 kV transmission lines. The low-voltage grid is operated by local distribution companies.

Real-time Supply Output

The current hourly output by fuel type reported on the homepage and the Power Data page represents the production values of transmission-connected generation. This real-time data comes from the hourly Generator Output and Capability report, that provides output levels from generators, registered as market participants, with capacities of 20 megawatts (MW) or greater.

Distribution-connected generation (also known as embedded generation) is not reported through the Generator Output and Capability report. More information can be found in the distribution-connected generation section.

Current Installed Capacity

Ontario’s supply mix has significantly changed over the last decade—wind, solar, bioenergy, waterpower, refurbished nuclear and natural gas-fired resources have replaced Ontario’s coal fleet. The current Reliability Outlook reports that Ontario's installed (transmission-connected) generation capacity totals 38,193 MW. The amount of generation actually available from day-to-day is dependent on current conditions, including facility outages (planned maintenance or unplanned).

Ontario's current installed generation capacity includes*:

*Note that these figures do not include generators that operate within local distribution service, except for those that participate in the IESO-administered market. Most solar facilities in Ontario are currently connected to the distribution system.

Source: Reliability Outlook, released March 21, 2024 updated quarterly.

Monthly Energy Output by Fuel Type

The Generator Output by Fuel Type Monthly report contains monthly values of total output, grouped by fuel type. It includes facilities as reported through the real-time supply output above, as well as facilities with installed capacity of less than 20 MW that are transmission-connected. This report does not include embedded generation. More information on embedded generation can be found in the distribution-connected generation section.

Yearly Energy Output by Fuel Type

The graph and figures below report the yearly 2022 output by fuel type. It includes facilities as reported through the real-time supply output above, as well as facilities with installed capacity of less than 20 MW that are transmission-connected. These figures do not include embedded generation. More information on embedded generation can be found in the distribution-connected generation section.

Donut chart displaying energy output by source for 2023

Year	Nuclear	Hydro	Gas/Oil	Wind	Biofuel	Solar
2022	78.8 TWh 53.7%	38.0 TWh 25.9%	15.2 TWh 10.4%	13.8 TWh 9.4%	0.3 TWh <1%	0.75 TWh <1%
2021	83.0 TWh 58.2%	34.2 TWh 24%	12.2 TWh 8.6%	12 TWh 8.4%	0.4 TWh <1%	0.75 TWh <1%
2020	87.8 TWh 60%	36.9 TWh 25%	9.7 TWh 7%	11.8 TWh 8%	0.4 TWh <1%	0.8 TWh <1%
2019	90.4 TWh 61%	36.4 TWh 25%	9.5 TWh 6%	11.0 TWh 7%	0.4 TWh <1%	0.7 TWh <1%
2018	90.1 TWh 61%	36.2 TWh 25%	9.6 TWh 6%	10.7 TWh 7%	0.4 TWh <1%	0.6 TWh <1%
2017	90.6 TWh 63%	37.7 TWh 26%	5.9 TWh 4%	9.2 TWh 6%	0.4 TWh <1%	0.5 TWh <1%
2016	91.7 TWh 61%	35.7 TWh 24%	12.7 TWh 9%	9.3 TWh 6%	0.49 TWh <1%	0.46 TWh <1%

Year

Nuclear

Hydro

Gas/Oil

Wind

Biofuel

Solar

2022

78.8 TWh

53.7%

38.0 TWh

25.9%

15.2 TWh

10.4%

13.8 TWh

9.4%

0.3 TWh

<1%

0.75 TWh

<1%

2021

83.0 TWh

58.2%

34.2 TWh

24%

12.2 TWh

8.6%

12 TWh

8.4%

0.4 TWh

<1%

0.75 TWh

<1%

2020

87.8 TWh

60%

36.9 TWh

25%

9.7 TWh

11.8 TWh

0.4 TWh

<1%

0.8 TWh

<1%

2019

90.4 TWh

61%

36.4 TWh

25%

9.5 TWh

11.0 TWh

0.4 TWh

<1%

0.7 TWh

<1%

2018

90.1 TWh

61%

36.2 TWh

25%

9.6 TWh

10.7 TWh

0.4 TWh

<1%

0.6 TWh

<1%

2017

90.6 TWh

63%

37.7 TWh

26%

5.9 TWh

9.2 TWh

0.4 TWh

<1%

0.5 TWh

<1%

2016

91.7 TWh

61%

35.7 TWh

24%

12.7 TWh

9.3 TWh

0.49 TWh

<1%

0.46 TWh

<1%

Percentages may not add up to 100 due to rounding.

See the Year-End Data page for historical energy output by fuel type.

Contracted Electricity Supply on the Transmission Grid

The quarterly Progress Report on Contracted Electricity Supply provides a status of the IESO’s contracted generation capacity in both the Ontario transmission and distribution grids.

This data may differ from the current supply mix, which describes all grid-connected generation that has completed the market entry process and a small amount of embedded generation that participates in the IESO-administered market.

The status of contracted electricity supply in Ontario can be found on the Contract Data and Reports web page.

IESO Active Generation Contract List

The IESO Active Generation Contract List provides the status of individual contracted electricity supply projects within different IESO procurement programs. The list is limited to generation facilities under contract to the IESO. More information on the contract list can be found on the Contract Data and Reports web page.

Generation Renewal

Ontario's electricity sector is going through a process of renewal — with the replacement of aging infrastructure and the transition to a more sustainable energy supply mix. Here’s a list of new generation scheduled to come in service within the next 18 months. Also included below is an overview of new and refurbished generation projects of 20 MW or more that have been commissioned, as well as units that have been retired since 2002.

Source data: Reliability Outlook

Committed Generation Resources

2025 Q2

Oneida Storage

235 MW

New and Retired Generation Since the IESO Market Opened in May 2002

2023

	Romney Wind Energy Centre	60 MW
	Beck 1 New G1	59 MW
	Beck 1 New G2	59 MW

2022

Nation Rise

100 MW

2021

	Calstock	-38 MW
	Henvey Inlet Wind Farm	300 MW

2020

	Loyalist Solar	54 MW
	Napanee Generating Station	985 MW

2019

	Nanticoke Solar	44 MW
	Yellow Falls Generating Station	16 MW

2018

	Amherst Island Wind	74 MW
	North Kent Wind 1	99.1 MW
	Belle River Wind	100 MW
	Namewaminikan Hydro	10 MW
	Thunder Bay Generating Station	-153 MW
	Fort Frances Unit	-47 MW

2017

	Niagara Region Wind Farm	230 MW
	Peter Sutherland Senior Generating Station	29 MW
	South Gate Solar	50 MW
	Windsor Solar	50 MW
	Greenfield South (Green Electron Power)	334 MW
	Bow Lake Phase 1 and 2b	60 MW

2016

	Grand Bend Wind Farm (Zurich)	99 MW
	Northland Power Solar Empire	10 MW
	Northland Power Solar Abitibi	10 MW
	Northland Power Solar Martin's Meadow	10 MW
	Northland Power Solar Long Lake	10 MW
	Grand Valley Wind Farms (Phase 3)	40 MW
	Armow Wind	180 MW
	Cedar Point Wind Power Project Phase II	100 MW

2015

	Thunder Bay Unit Converted to Burn Biomass	153 MW
	Grand Renewable Energy Park (Grand SF)	100 MW
	Jericho Wind Energy Centre	150 MW
	Adelaide Wind Power (Landon)	40 MW
	Dufferin Wind Power (Shannon)	91.3 MW
	Goshen Wind Energy Center	102 MW
	Grand Renewable Energy Park (Grand WF)	149 MW
	Goulais Wind Farm	25 MW
	K2 Wind Project	270 MW
	Bornish Wind Energy Centre	74 MW
	Adelaide Wind Energy Centre	60 MW
	Nuclear Upgrade at the Bruce Power Plant	31 MW
	Kingston Solar Project	100 MW
	Thunder Bay Condensing Turbine Project	40 MW
	Old Smoky Falls Units	-53 MW

2014

	Three new hydraulic units at Smoky Falls	264 MW
	Third hydraulic unit at Kipling Generating Station	79 MW
	Erieau Wind	99 MW
	Port Dover and Nanticoke Wind Project	105 MW
	Third Unit at Little Long	67 MW
	Liskeard 1,3 and 4	30 MW
	Thunder Bay Units 2 and 3	-306 MW
	New Third Unit at Harmon	78 MW
	South Kent Wind (Railbed)	270 MW
	McLean's Mountain Wind Farm	60 MW
	Bluewater Wind Energy Centre (Blake)	60 MW
	East Lake St. Clair	99 MW
	Summerhaven Wind Energy Centre	125 MW
	Atikokan Converted to burn Biomass

2013

	Comber Wind	166 MW
	Pointe Aux Roches Wind Farm (Paroches)	49 MW
	Lambton Coal Shutdown	-1,016 MW
	Nanticoke Coal Shutdown	-1,985 MW

2012

	Atikokan Unit Shutdown	-211 MW
	Bruce Units 1 and 2	1,552 MW
	York Energy Centre	438 MW

2011

	Greenwich Wind Farm	99 MW
	Gosfield Wind	50 MW
	Raleigh Wind Energy Centre (Dillon)	78 MW
	Nanticoke Units 1 and 2 shutdown	-980 MW

2010

	Thorold cogeneration	287 MW
	Halton Hills Generating Station	705 MW
	Nanticoke and Lambton unit shutdowns	-1,950 MW
	Conversion of Fort Frances to biofuel	47 MW
	Talbot Wind Farm (Spence)	99 MW
	Kruger Energy Chatham Wind (Portalma T3)	101 MW

2009

	St. Claire Energy Centre	678 MW
	Portlands Energy Centre (Combined Cycle)	246 MW
	Goreway Station	942 MW
	Beck Unit 7 conversion	69 MW
	Beck 2 upgrades	68 MW
	Enbridge Ontario Wind Farm (Underwood)	182 MW
	Wolfe Island Wind Farm	198 MW
	East Windsor Cogeneration	100 MW

2008

	Portlands Energy Centre (Simple Cycle)	394 MW
	Greenfield Energy Centre	1,153 MW
	Umbata Falls	24 MW
	Kruger Energy Port Alma (T1) Wind Project (Portalma T1)	101 MW
	Melancthon II (Amaranth)	132 MW

2007

	Abitibi Canyon (Upgrades)	20 MW
	Ripley Wind	76 MW

2006

	Greater Toronto Airport Authority	117 MW
	Melancthon Wind (Amaranth)	68 MW
	Kingsbridge	40 MW
	Erie Shores Wind Farm (Port Burwell)	99 MW
	Prince Wind	99 MW
	Prince II Wind	90 MW

2005

	Pickering Unit 1	515 MW
	Lakeview (Retirement)	-1,130 MW

2004

	Bruce Unit 3	782 MW
	Brighton Beach	580 MW
	Kirkland Lake	32 MW
	Beck and Kipling (Upgrades)	80 MW

2003

	Pickering Unit 4	515 MW
	Bruce Unit 4	770 MW

Note:

An asterisk (*) denotes the project has achieved commercial operation but has not met all the commissioning requirements of the IESO.

Some facilities have been combined in name (resulting in an increase in capacity) or have changed their name from when being first registered into the system. The list above is the original record when they first commissioned onto the system. The Generator Output and Capability Report includes a list of all facilities over 20 MW and their current output connected to the IESO-controlled grid.

Nuclear Power Generating Stations

Nuclear power represents approximately 13,000 MW or over 30 percent of Ontario's installed generation capacity. Ontario's three nuclear facilities typically produce about 60 percent of the province's electricity.

Read more about Ontario's nuclear power generating stations.

Site	Bruce	Darlington	Pickering
Location	Kincardine	Clarington	Pickering
Installed Capacity	6,300 MW	3,500 MW	3,100 MW
Number of Units	8	4	6
Operator	Bruce Power	Ontario Power Generation	Ontario Power Generation
Refurbishment and Continued Operations Schedule	Two units (1 & 2) were refurbished and brought back into service in 2012. The IESO signed an agreement with Bruce Power in December 2015, securing 6,300 MW of electricity and enabling the refurbishment of the remaining six units, beginning in 2020.	OPG started the refurbishment of the first unit at the Darlington station in October 2016. Darlington refurbishment is scheduled for completion by 2026.	Two units will be retired at the end of 2022 and four units will be retired at the end of 2024.
Cost Recovery	Generation contract with IESO. More information is available on the Energy Procurement and Contracts Archive web page.	Regulated rates set by Ontario Energy Board.	Regulated rates set by Ontario Energy Board

Supply Overview