The New South Wales government plans 24 new pumped hydro projects that would provide about half of the state's demand for electricity on the hottest days and three times the power of Snowy 2.0.

It follows the NSW government's launch of a pumped hydro roadmap designed to ramp up the development of new hydro storage projects and back up the rising levels of new wind and solar generation.

Pumped hydro storage will be used to back up the rise of new wind and solar generation. Credit:Andrew Sheargold

The 24 proposed projects come after the federal government worked with the Australian National University to identify about 22,000 reservoirs that could be used to form around 98,000 possible pumped hydro projects around the country.

Pumped hydro works by running water from a dam downhill through a turbine to generate electricity and then using excess energy to pump it back up the hill to run through again.