The share of coal in eastern Australia's electricity generation network has continued to recede, along with carbon emissions, despite a March heatwave that lifted power demand for the first time in 16 months.

The widespread and prolonged heat over the country's south-east early last month prompted the biggest peak in demand for the entire summer. It was enough to trigger a 0.01 per cent annualised gain in electricity demand on the National Electricity Market for March, the first increase since November 2011, monthly research by consultants Pitt and Sherry shows.

Although coal-fired power plants raised output to meet the extra load on the peak day, March 12, their proportion of total generation eased another 0.2 percentage points to 74.6 per cent for the month. In February, their share of the electricity market fell below 75 per cent for the first time.

Hydro, wind and solar edged higher to a record share of 12.6 per cent, shows the Cedex report, while gas increased 0.1 percentage point to 12.8 per cent.

Carbon emissions intensity eased to 835 kilograms a megawatt-hour, down from 837 kilograms in February.