But the IEA also defended subsidies in renewable energy technology as a necessary means to create a clean and independent energy supply system.

In the past, the IEA has been criticized by environmental groups for underplaying the role of renewable energy technologies in favor 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 renewable energy deployment," the report said.

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 gigawatts."

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

The renewable energy sector had grown by nearly 18 percent between 2005 and 2009, and this growth was evidence it could deliver the intended policy benefits of improved energy security, greenhouse gas reductions and other environmental benefits, as well as economic development opportunities.

"Each of the sectors has been growing strongly, at rates broadly in line with those required to meet the levels required in IEA projections of a sustainable energy future."

Of all renewable energy technologies, the report said hydropower remained the major source of renewable electricity, at 84 percent of renewable generation, which corresponded to about 16 percent of total generation in 2009.

Other renewable electricity technologies have grown by nearly 74 percent between 2005 and 2009, it said.

"Wind has grown most rapidly in absolute terms and has overtaken bioenergy. Solar has grown at a compound annual growth rate of 50.2 percent, and installed capacity reached about 40 gigawatts by the end of 2010," the report said.

Maintaining renewable energy’s rapid growth

A new book from the International Energy Agency released on Wednesday provides guidance for policy makers and other stakeholders to avoid past mistakes, overcome new challenges and reap the benefits of deploying renewables – today and tomorrow. In launching the book, IEA Executive Director Maria van der Hoeven said deployment of renewable energy must be stepped up - especially given the world’s increasing appetite for energy and the need to meet this demand more efficiently and with low-carbon energy sources.

"As the IEA’s analysis has shown, without an urgent and radical change of policy direction, the world will lock itself into an insecure, inefficient and high-carbon energy system," Ms. Van der Hoeven said.

"Renewables already play a central role in fostering sustainability and energy security, and their significance will only grow in the coming decades. Against this backdrop, Deploying Renewables 2011 provides a major review of renewable energy markets and policies at this critical juncture."

New challenges have come to the fore: Growth in renewable energy has so far focused on just a few of the available technologies, and rapid deployment is confined to a relatively small number of countries.

In more advanced markets, managing support costs and system integration of large shares of renewable energy in a time of economic weakness and budget austerity has sparked vigorous political debate.

The new IEA book builds on and extends a 2008 publication, drawing in recent policy and deployment experience worldwide. It also:

* Provides a comprehensive review and analysis of renewable energy policy and market trends
* Analyses in detail the dynamics of deployment and provides best-practice policy principles for different stages of market maturity
* Assesses the impact and cost-effectiveness of support policies using new methodological tools and indicators
* Investigates the strategic reasons underpinning the pursuit of renewable energy deployment by different countries and the prospects for globalisation of renewable energy.

Source and more information: IEA website