Australia could be powered almost entirely by renewable energy in coming decades, says a new report.

But the renewables expansion needs to be large and sustained with investment growth encouraged by policy certainty, says the report, "Generating a Renewable Australia" from the Climate Commission.

The release of the report Monday in Sydney coincided with the opening of the U.N. Climate Change Conference in Doha. It also follows the appointment, announced over the weekend, of former Macquarie Group investment banker Oliver Yates as chief executive of the Clean Energy Finance Corp., the organization charged with funding development of Australia's renewable energy sector, with an annual budget of $2 billion.

Solar PV and wind energy could be the cheapest forms of power in Australia for retail users by 2030 or sooner as carbon prices rise, says the report.

As of July 2012, almost 754,000 Australian households and businesses had installed solar panels.

South Australia's wind energy per capita is higher than any major country in the world, the report says, contributing approximately 26 percent of the state's current total electricity production.

"What we can now see is the emerging inevitability that renewables are going to be running the economy at some point in the future," Climate Change Commissioner Tim Flannery told the Australian Broadcasting Corp.

"We saw more money invested in 2011 in clean technologies than in fossil fuel," Flannery said. "So we've crossed the threshold. We need to prepare ourselves for a very different energy grid in the future."

In the meantime, Australia's electricity generation -- about three-quarters of which comes from coal -- accounts for 35 percent of the country's emissions, the report says.

The Australian government's energy white paper released this month says that clean energy technologies can provide 40 percent of the country's electricity by 2035, which experts say means that fossil fuels will dominate for at least the next 20 years.

"To avoid the most damaging consequences of climate change we must virtually eliminate greenhouse gas emissions from fossil fuels within decades," the report states.

Mark Diesendorf, deputy director of the Institute of Environmental Studies at the University of New South Wales, says the Climate Commission's report neglects to address the barriers to the growth of Australia's renewable energy sector, including annual fossil fuel subsidies of more than $10 billion.

"Obviously they are trying to put a rosy glow on the situation to avoid criticizing federal and state governments," Diesendorf was quoted as saying by The Conversation.