Zero Energy Homes.

It is expensive, but it is possible to build a home that requires no external energy. In style, it costs $1 million and if you're thinking more along trailer park lines, you can do it for $250,000. The truth is, that because technology for big plants advances, as well as more localized energy generation, most of society will probably never leave the grid. But, much of the zero energy equation comes from conservation, rather than power generation, and those innovations do have a great potential.