An Australian-led team of scientists say they have found a safe way to carry out carbon capture and storage.

"The results verify that it is a valid way of cutting down on greenhouse gas emissions, particularly CO2," says Professor Peter Cook of the Cooperative Research Center for Greenhouse Gas Technologies Otway Project in southwestern Victoria of Australia, which conducted the study, the Australian Broadcasting Corporation reports.

Carbon capture and storage involves capturing carbon dioxide from a stationary source, such as a power station, and storing it underground. The method is controversial mostly because of the possibility that the stored CO2 could leak.

For the Australian study, which began in 2008, scientists injected compressed gas in liquid form 1.2 miles below the surface into permeable sandstone in a depleted natural gas field. A cap of impermeable mudstone rocks overlying the gas reservoir was used to prevent the CO2 from escaping into the air or the ground, with movement of the CO2 tracked by seismic imagery and fluid sampling.

"Monitoring showed that there has been no measurable effect of stored CO2 on soil, groundwater, or atmosphere," the scientists concluded in their findings, published this week in the Proceedings of the National Academy of Sciences.

"The Otway Project has confirmed that storage in depleted gas fields can be safe and effective and that these structures could store globally significant amounts of carbon dioxide," the report's lead author Charles Jenkins from the Commonwealth Scientific and Industrial Research Organization of Australia, said in a statement.

Still, some experts say that the Otway project, which tested the storage of around 66,000 tons of CO2 over several years, is too small to evaluate CCS on a commercial scale.

"A typical coal plant emits the order of 10,000 to 40,000 tons of CO2 per day so this storage demonstration is still an order of magnitude or more smaller than required for such plants," said Iain MacGill of the Center for Energy and Environmental Markets at the University of New South Wales.

Separately, the International Energy Agency's chief economist Fatih Birol, speaking Monday in Canberra, said it would be "virtually impossible" to limit global temperature rises to 2 degrees Celsius without CCS.

An IEA report this year calls for around 100 large-scale CCS projects by 2020 and more than 3000 by 2050. While the agency says 70 such projects are being planned, it acknowledges that delays in funding for CCS are partly due to the high costs of the technology and lack of public support.