A rush to take advantage of the carbon price has given renewable energy its largest share of eastern Australia's electricity market since at least the Whitlam years, with black coal fired plants losing the most ground.

Rising hydro power exports from Tasmania leading up to the possible end of the carbon tax and new wind farms pushed the share of renewable energy in the national electricity market (NEM) up to 9.6 per cent for hydro and 4.4 per cent for wind last month, analysts Pitt & Sherry said. The firm's latest Cedex report also showed a sharp drop in output from black coal fired power plants. Coal's share of the NEM fell to 74 per cent.

''The effect on NSW generators is quite severe,'' the report said, noting Bayswater and Liddell, the two big state-owned power plants, averaged just 60 per cent and 45 per cent loads, respectively, over the past few months.

Eraring, owned by Origin Energy, had loads averaging less than 40 per cent, while Queensland's main state-owned power plants operated with 30 per cent to 65 per cent loads, the Cedex report says.