"There is a risk that Nova Scotia's current air quality regulations for the electricity sector will not be able to meet future federal air pollutant requirements and/or meet the requirements for an equivalency agreement," they say.
The briefing notes, prepared by the province's Environment Department for Energy Minister Andrew Younger soon after the Liberals took power in October, say the issue is being monitored closely. They were obtained by The Canadian Press under access to information laws.
Jason Hollett, executive director of the Environment Department's sustainability and innovation division, said there is a concern because the province has its own regulations for air pollutants while Environment Canada has not yet set federal regulations.
"So we have no idea if ours will be adequate or no idea if ours will be in the proper time frame," Hollett said.
Nova Scotia's regulations cover pollutants emitted by coal-fired power plants that include mercury, nitrogen oxide and sulphur dioxide. Under those regulations, Nova Scotia is required to reduce pollutants in 2014 and again in 2020.
For instance, there is a 65-kilogram cap on mercury emissions that takes effect this year, to be followed by a cap of 35 kilograms in 2020.
Hollett said once the federal government sets its regulations, the province may be in a position, if necessary, to negotiate an equivalency agreement similar to one it signed in 2012 on greenhouse gas emissions. That agreement, which takes effect in July 2015, allows Nova Scotia to gradually phase out coal-fired plants under its own rules for greenhouse gases, but sets no deadlines for closures.
Hollett said that means coal is likely to be part of Nova Scotia's energy makeup for the "foreseeable future."
"You have to have a consistent and reliable base load of electricity and right now that infrastructure is provided by coal," Hollett said.
He said the province's push towards a greater reliance on renewable energy has meant its dependence on coal has shrunk from a high of close to 90 per cent in 2007 to a low of 57 per cent in 2012. But he said coal power generation rose again last year after higher gas prices made it more economical, though not near historical levels.
Catherine Abreu, energy co-ordinator for the Halifax-based Ecology Action Centre, said the concern over pollution targets illustrates the need for the province to stop burning coal.
However, Abreu said that can't happen without a practical plan to meet power demands as coal is phased out.
"We need to invest in a diversity of options," said Abreu. "That means a very large-scale infrastructure shift needs to be planned for and engineered."
She said such plans should be a prominent part of the discussion during upcoming public consultations on the province's energy future.
Nova Scotia has some of the highest polluting power plants in North America, according to the province.