Renewable energy technology is becoming increasingly cost competitive and growth rates are in line to meet levels required of a sustainable energy future, the International Energy Agency (IEA) said.

The report also said subsidies in green energy technologies that were not yet competitive are justified in order to give an incentive to investing into technologies with clear environmental and energy security benefits.     

The renewable electricity sector has grown rapidly in the past five years and now provides nearly 20 percent of the world's power generation, the IEA said during the presentation of the report titled Deploying Renewables 2011.

"We have an estimate of 300 million tonnes of avoided CO2 until now thanks to renewable technologies," Paolo Frankl, the IEA's Head of Renewable Energy Division, said.

The IEA's report disagreed with claims that renewable energy technologies are only viable through costly subsidies and not able to produce energy reliably to meet demand.

"They (renewables) are becoming competitive, and we can improve security, green house reductions and economic sustainability," the IEA's Executive Director Maria van der Hoeven said.

"The portfolio of RE technologies, which includes established hydro power, geothermal and bioenergy technologies is now, therefore, cost-competitive in an increasingly broad range of circumstances, providing investment opportunities without the need for specific economic support," the report said, and added that cost reductions in other renewable technologies, such as wind and solar, were set to continue.

Van der Hoeven said that the renewable sector would have to grow fourfold within the next years in order for governments to achieve their climate goals, and that a significant policy effort was needed to push the sector to full competitiveness. 

For this reason, the IEA defended subsidies with a limited timeframe in renewable energy technology as a necessary means to create a clean and independent energy supply system.     

In the past, the IEA has been criticised by environmental groups for underplaying the role of renewable energy technologies in favour of nuclear and fossil-fuels.

"Where technologies are not yet competitive, economic support for a limited amount of time may be justified by the need to attach a price signal to the environmental and energy security benefits of RE deployment," the report said.     

Pointing to German solar subsidies, Van der Hoeven said that subsidies had started off at a high level and were adjusted downward once the technology had developed.

The majority of renewable energy growth is taking place in OECD countries and in major emerging markets like China, India and Brazil.

The report said "the OECD was the only region where the deployment of less mature technologies (such as solar PV, offshore wind) reached a significant scale, with capacities in the order of GWs."     

Most OECD countries have large-scale subsidies in place in order to develop renewable energy technologies. - Reuters