SaskPower's annual sustainability report raises concerns about federal regulations for coal-fired power plants.

The report says the proposed rules would stall work on carbon capture technology -- something that SaskPower has poured billions of dollars into.

But the report was written before SaskPower got a bit of breathing room from the federal government.

Ottawa recently announced regulations that say coal power plants must be shut down after 50 years -- the initial proposal was 45 years.

More than 40 per cent of SaskPower's generating capacity in 2011 came from coal.

The report says SaskPower needs to find better ways to keep using coal for fuel, since there's a 300-year supply in the province.

The utility is working on carbon capture and storage. The technology captures carbon dioxide emissions from coal-fired power plants and pumps them underground. SaskPower is spending $1.2 billion to turn one of its units at Boundary Dam, a coal-fired power plant, into a carbon capture unit.

Critics say not enough is known about the environmental consequences of burying carbon dioxide.