"The experts are saying the same about solar energy now. They note that after decades of development, solar power hardly supplies 1 percent of the world's energy needs. They say that solar is inefficient, too expensive to install, and unreliable, and will fail without government subsidies. They too are wrong. Solar will be as ubiquitous as cellular phones are.
Futurist Ray Kurzweil notes that solar power has been doubling every two years for the past 30 years — as costs have been dropping. He says solar energy is only six doublings — or less than 14 years — away from meeting 100 percent of today's energy needs. Energy usage will keep increasing, so this is a moving target. But, by Kurzweil's estimates, inexpensive renewable sources will provide more energy than the world needs in less than 20 years. Even then, we will be using only one part in 10,000 of the sunlight that falls on the Earth."
http://www.washingtonpost.com/blogs/innovations/wp/2014/09/19/the-coming-era-of-unlimited-and-free-clean-energy/?wpisrc=nl-inn&wpmm=1