South Australian Premier Jay Weatherill wants his government to be powered completely by green energy by 2017.
The government has called on companies to submit proposals to supply all electricity for government sites from low-carbon sources - such as wind and solar - after current agreements expire over the next two years.
It's part of Mr Weatherill's plan to make Adelaide the world's first carbon-neutral city and to have half of the state's total energy sourced from renewables by 2020.
"We are determined to make Adelaide a showcase city for low-carbon and clean technologies, to attract investment, drive innovation and create new jobs," Mr Weatherill said.
Green groups have welcomed the government's latest proposal, but are concerned it still allows for the use of gas.
"We are seriously concerned that the state government hasn't ruled out buying power from gas facilities when we should be focusing on building clean, renewable energy power plants," the Australian Youth Climate Coalition said.
Repower Port Augusta, a coalition of green groups, says a plan to power SA government buildings with low-carbon alternatives could help bring a solar thermal power plant to the state's mid-north.
"This is a great step forward and could get solar thermal in Port Augusta over the line," a spokeswoman said.
Alinta Energy has two coal-fired power plants at Port Augusta but plans to close them by the end of March.
The company has investigated developing a solar thermal power plant but says it's unviable given market conditions and current technology.