An intense battle among electricity producers in Australia is being won by coal-fired power plants, sending carbon emissions climbing, energy consultants Pitt & Sherry say.

With demand in the national electricity market (NEM) all but flat, "extreme competition" existed between clean energy being forced into the sector from the renewable energy target and surplus capacity among coal-fired power stations, Phil Harrington, a principal consultant with the firm, said.

AGL's Loy Yang A power plant, Australia's largest carbon emissions plant. Credit:Bloomberg

"At the moment, coal is winning," Mr Harrington said, noting coal's share of the NEM – serving Australia's eastern states – reached 75.6 per cent at the end of October, up more than 3 percentage points since the end of the carbon tax in June 2014.

"Over the long term, our view is quite pessimistic about emissions from the NEM in the absence of a carbon price," he said.