How's this sound: giant solar arrays in orbit around the Earth, harvesting undiluted and virtually endless power from the sun and then beaming it straight down to the ground with lasers. Badass, right? And according to a three-year, ten-nation, peer-reviewed study by the International Academy of Astronautics, we could make it happen within ten years.
Can you name solar power's biggest downside? Sure you can! It doesn't work when the sun isn't out, which is the case most of the time when it's cloudy and all the time at night. This is why satellites all rely on solar panels: unless something catastrophic happens (in which case eco-friendly power will be the least of your worries), it's always sunny and never cloudy up in space.
The obvious solution, then, is to move all of our solar power generating capacity into orbit, where we can rely on it 24/7. The International Academy of Astronautics has been researching a plan that would put a bunch of several-mile wide solar arrays into Earth orbit above the equator. These arrays would be able to collect as much as twice the amount of power as their earthbound kin, and using either microwaves or lasers, they could beam electricity to anywhere on Earth.
While this all might seem a bit far-fetched, according to the IAA research, we'll have the technology to do it within 10 years, and it'll make economic sense to do it within 30. The up-front expense is a completely different issue, but if we've got a handy fleet of private launch vehicles all trying to undercut each other by then, a test project could be launched in about 20 years for just a few tens of billions of dollars.