Ontario will build new nuclear reactors and refurbish existing ones as part of a multi-billion energy plan to ensure the province can meet increasing energy demands.

Tuesday's strategy announcement comes after a December report by the Ontario Power Authority, which called for $70 billion in electricity generation spending over the next 20 years.

The report also called for more than half of the spending to go toward nuclear projects to ensure Ontario has adequate energy supplies in the future.

"Our vision is for an Ontario with a safe, clean, reliable, secure and affordable supply of electricity," said Energy Minister Dwight Duncan.

Existing reactors at the Darlington and Pickering stations will be refurbished, and the government plan calls for Ontario Power Generation to conduct environmental assessments for new reactors at an existing nuclear site.

Duncan said the plan doubles conservation efforts and will generate six per cent less nuclear power than the December report recommended.

Energy experts have said Ontario will face serious shortages after 2013 if significant sources of new power are not created.

The government's strategy defers a decision to outside advisors as to when Ontario should close its remaining coal-fired plants.

Last week, Duncan delayed for a second time the closure of the province's remaining coal-fired power plants.

The Liberals made it an election promise to shut them down because of air pollution concerns, but now say the power they generate is needed until new energy sources become available.

Despite the delay, however, the Liberals still plan to close the plants.

The government last week said power consumption is increasing so quickly in Ontario that it is becoming difficult to keep up with demand.

Office protest

Seven members of Greenpeace chained themselves together in Duncan's office Tuesday to protest the province's energy plan.

Protester Dave Martin called the plan for more nuclear reactors "disastrous" for Ontario.

Security officials sealed off access to the floor where the protesters were located.

The Sierra Club of Canada also condemned the plan, calling it an "unnecessary environmental and economic risk."

"Unfortunately this government has ignored the massive energy gains that conservation and energy efficiency have to offer," Sierra Club Ontario Chapter Director Dan McDermott said in a written statement. "And instead is embarking on an irresponsible path towards dangerous, expensive and unreliable nuclear power."

"We can go clean and green or we can go nuclear, there isn't enough money to do both," McDermott added.

The environmental group also raised the specter of possible terrorist attacks.

The group's senior policy advisor, John Bennett, led a group of three people into the Bruce Nuclear facility in the 1970s to highlight lax security.

"Is there a security system that can never be defeated," Bennett asked in the written statement. "If I can do it, anyone can."

Highlights of the new energy plan:

• Refurbishing nuclear reactor units at Darlington and Pickering, and environmental assessments for new reactors at an existing nuclear site;
• Limiting total nuclear power capacity in Ontario to 14,000 megawatts, the same as Ontario has now, in 2025;
• Calls for Ontario Power Authority to determine how long coal plants will still be required;
• Calls for coal power to eventually be replaced with cleaner sources of energy;
• Enhanced transmission lines to carry more power across the province;
• Doubling the conservation efforts recommended in a December report by the Ontario power authority, to reduce demand by 6,300 megawatts by 2025; and
• Doubling the amount of electricity Ontario gets from renewable energy sources like wind power, to a total of 15,700 megawatts by 2025.

With a report from CTV Toronto's Austin Delaney and files from The Canadian Press