CANBERRA, June 3 -- Australia's peak scientific research body has claimed a major breakthrough in renewable energy that it claims has the potential to make solar cost-competitive with coal and gas as a source of power.

The Commonwealth Scientific and Industrial Research Organization (CSIRO), a federal government agency, on Tuesday announced it had used solar energy to generate hot and pressurized "supercritical" steam at the highest temperatures achieved anywhere in the world outside of fossil fuel sources.

Supercritical steam is used to drive the most advanced power stations in the world. Currently, only coal or gas is used to drive these stations, but the solar-generated supercritical steam produced by CSIRO might now offer a clean energy alternative at comparable prices.

Dr Alex Wonhas, CSIRO's energy director, described the breakthrough as "a game-changer for the renewable energy industry" . "It's like breaking the sound barrier; this step change proves solar has the potential to compete with the peak performance capabilities of fossil fuel sources," Dr Wonhas said. "Instead of relying on burning fossil fuels to produce supercritical steam, this breakthrough demonstrates that the power plants of the future could instead be using the free, zero emission energy of the sun to achieve the same result."

Supercritical solar steam is water pressurized at enormous force and heated using solar radiation.

About 90 percent of Australia's electricity is generated using fossil fuel, but only a small number of power stations are based on the more advanced supercritical steam.

The world record, set last month, was at a pressure of 23.5 megapascals (a measure of force per unit area), and temperatures up to 570 degrees Celsius.

Commercial solar thermal power plants around the world use subcritical steam, operating at similar temperatures but at lower pressure.

If these plants were able to move to supercritical steam -- that is, increase the force at which water is pressurized to create steam -- it would increase their efficiency and help to lower the cost of solar electricity, which has previously restricted its commercial viability.

The 9.7 million AU dollar (8.97 million U.S. dollar) research program is supported by the Australian Renewable Energy Agency ( ARENA) and is part of a broader collaboration with Abengoa Solar, the largest supplier of solar thermal electricity in the world.

CSIRO and Abengoa Solar, with support from ARENA, are developing advanced solar storage to provide solar electricity at any time, day or night.

The breakthrough was made at the CSIRO Energy Centre in Newcastle, about 160km north of Sydney and home to Australia's low emission and renewable energy research.

The city and surrounding region is, coincidentally, famous for its coal, with Newcastle being the largest coal exporting harbor in the world.

The energy center includes two solar thermal test plants featuring more than 600 mirrors (heliostats) directed at two towers housing solar receivers and turbines.

ARENA chief executive Ivor Frischknecht said there was still work to be done before the technology was ready for commercialization but it was nevertheless an important development. "This breakthrough brings solar thermal energy a step closer to cost competitiveness with fossil fuel generated power," Frischknecht said.