The quest for a clean, environmentally-friendly, and sustainable development, besides the questions on the security of oil supplies and prices, will drive the use of renewable energy. Its rate of growth, however, is contingent on the implementation of policies, development of renewable energy technologies to meet the energy needs of the world and at a cost that is competitive with conventional fuels.

Notwithstanding, the following are a sample of factors in the global effort driving the use of renewables, fuelling a perceptible trend for the future:

• 48 or more countries have some form of policy promoting the use of renewable energy. More are expected to adopt such policies.
  
  
• Over 40 countries have a policy target for the use of renewable energy. This includes all the 25 member-states of the EU.
  
  
• The EU has a target of 12.0% of renewables in their energy mix by 2010, extending to 20.0% by 2020. They are also targeting to have 21.0% of their electricity to be generated by renewables.
  
• China targets to have 10.0% of its electricity supplied from renewables by 2010, not including large hydropower.
  
  
• The state of California in the U.S. has just enacted the largest solar program, the California Solar Initiative. With funding of US$2.9 billion, they aim to have one million solar roofs over a ten-year period until 2017. The objectives of this initiative are also to clean up their environment and to reduce the cost of solar electricity.
  
  
• The World Bank Group (WBG) driving a program to help power-up developing countries and rural areas through the use of renewable energy, targeting “a 20% average annual growth in renewable energy and energy efficiency commitments”. In 2006 alone, the WBG provided US$860 million in financial support to the program.

Expectations in the growth of the use of renewable energy are almost academic now. The question is how much growth would be generated by these factors, when, and for how long. Encapsulating the factors driving the growth of renewable energy, the European Renewable Energy Council (EREC), in collective agreement with its member associations, stated that “based on experiences and cumulative knowledge lead to assumptions on expected annual installations growth rates for different technologies and show that by 2040, a share of renewable energy up to 50% worldwide is possible”. In contrast, the IEA expects renewables to have a 14.0% share, while the EIA foresees only a 9.0% share, both by 2030.

In EREC's outlook, two scenarios were provided, an aggressive scenario with assumption of implemented clean energy policies leading to renewables supplying 50.0% of the world's energy needs. Under this scenario, PV, wind, and solar thermal could see the fastest rate of growth among renewables. In the other less aggressive scenario, generally similar to current conditions, renewables are seen to be able to provide a, yet very promising, 27.0% of the world's energy demand. Under this scenario, albeit slower growth rates, PV, wind and solar thermal would still be the leading growth sectors for renewables.