While I studied at Florida State University, I got to experience, just how an "Off-Grid Zero Emission Building" worked. It had the most up-to-date technology when it came to sustainability.
Hydrogen Based Energy Storage System:
While Solar Panels are a great way to convert the sun's energy into electricity directly, this is only useful when the sun shines constantly (So great for Florida but maybe not for Alaska).
Instead, research has been growing to create a system that will use the unused energy from the house to power an "electrolyzer", that (in less technical terms) will essentially power the house even without sunlight. The only by-product of this system is water.
This system, when implemented will be one of the world's first hydrogen powered homes and will hopefully provide greater opportunities for future homes.