Instead the Energy Ministry said in the plan released this week it will encourage conservation and demand management programs before building new generation.

The Ministry said consumer costs will still rise under the new plan but less than in the last plan in 2010, even though Ontario will phase out its coal-fired generation by the end of 2014.

According to the new plan, residential power bills are expected to rise about 2.8 percent a year for the next 20 years, down from a forecast increase of 3.5 percent under the 2010 plan, the Ministry said.

Under the current plan, residential bills will rise to C$178 in 2018 from about C$138 a month in 2013. The 2010 plan forecast residential bills would reach C$191 a month in 2018.

The Ministry forecast Ontario's energy mix in 2025 at 42 percent nuclear, 46 percent renewable, and 12 percent natural gas. None would come from coal.

In 2013, Ontario produced 59 percent of its power from nuclear, 28 percent from renewable, 11 percent from natural gas and 2 percent from coal.

Ontario Power Generation (OPG), the province-owned power generator, has said it wants to refurbish the four reactors at its 3,512-megawatt Darlington plant, located along Lake Ontario about 70 km (43 miles) east of Toronto, to keep them running for another 25 to 30 years.

Under the latest plan, the Energy Ministry said OPG will work on Darlington 2 in 2016-2019, Unit 1 in 2019-2022, Unit 3 in 2021-2024 and Unit 4 in 2022-2025.

The Ministry has estimated the Darlington refurbishment cost at about C$6 billion to C$10 billion.

OPG also operates the 3,100-MW Pickering nuclear plant along Lake Ontario, about 40 km east (24 miles) of Toronto. OPG said it plans to spend about C$200 million to refurbish four of the six reactors at Pickering, Units 5-8, to keep them running through 2020, when the entire plant will retire.

The Ministry said OPG could retire some Pickering reactors sooner than 2020, depending on projected demand, the progress of fleet refurbishment and the completion of a new substation in Clarington.

Hydro One, the province-owned transmission company, expects to complete the Clarington substation, located between Pickering and Darlington, by 2017, according to the Ministry.

NO NEW REACTORS

OPG had been looking to build two new reactors at Darlington, and in 2012 signed agreements with Westinghouse Electric, a unit of Japanese multinational Toshiba Corp, and SNC Lavalin Group Inc's Candu Energy to prepare cost estimates.

The Energy Ministry said the deferral of the new reactors in the new plan reduced capital expenditures by up to C$15 billion.

Bruce Power, the other nuclear operator in Ontario, decided not to pursue construction of new reactors in 2009 due in part to weak market conditions.

Over the past few months, Bruce said it was ready to invest billions to refurbish the eight reactors at its 6,300-MW Bruce plant to keep them running through 2040. Bruce is located in Tiverton, about 225 km (139 miles) west of Toronto along Lake Huron.

The Energy Ministry said Bruce will work on Bruce 4 in 2016-2020, Unit 3 in 2019-2022, Unit 5 in 2022-2025, Unit 6 in 2024-2027, Unit 7 in 2026-2029 and Unit 8 in 2028-2031.

In September, Bruce said it was investing C$430 million to overhaul the 750-MW Units 2 and 3 during future planned outages to extend the reactors' lives.

Bruce Power is partnership between TransCanada Corp; Cameco Corp; Borealis Infrastructure Management, a division of the Ontario Municipal Employees Retirement System; the Power Workers' Union; the Society of Energy Professionals; and a majority of Bruce Power's employees.

(Reporting by Scott DiSavino; Editing by Jeffrey Benkoe)