Renewable energy will become second largest energy source

Should overtake natural gas by 2018.

Oil, however, will provide most of the energy needed to power the world by 2018, said the International Energy Agency.

IEA said current projections see a 40% growth in renewable energy over the coming five years, which would bring the total to about 25% of total energy consumption, with hydro still accounting for the lion's share at 17%.

In 2012, renewables grew 8% to 4,860 TWh, or as large as China's total energy demand.