A "game-changing" renewable energy source has been developed that marks a new frontier in power generation.

Supercritical steam was generated at the highest temperatures ever achieved in the world outside of fossil fuel sources by scientists at Australia's Commonwealth Scientific and Industrial Research Organisation.

The power source marks a breakthrough in solar energy and means the sun could one day be used to drive the most advanced power stations in the world, researchers said.

"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," said CSIRO's energy director Alex Wonhas.

CSIRO Solar tower 2 in operation.
CSIRO Solar tower 2 in operation. CSIRO

"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 steam is water pressurised at an enormous force and heated using solar radiation.

At present, commercial solar thermal power plants use subcritical steam, which work with the same method but at lower pressures. If these plants could use supercritical steam, they would increase efficiency and lead to cheaper solar electricity.

While researchers say there is still further research to be done, experts say it is a significant achievement in the development of solar power.

Ivor Frischknecht, chief executive of the Australian Renewable Energy Agency, which funded the research, said: "This breakthrough brings solar thermal energy a step closer to cost competitiveness with fossil fuel generated power."