I was sent a link through AIM by someone awhile ago which I had ready to pass on to you - it was a UPS (battery backup system) company that had a nitrogenic system that would power a home for nearly 3 days AFTER the main power sourse failed. The home in the example was massive, a typical home in todays 7 bed 4 bath market place around me.
It was fully emmission free and (to me) magical. It charged a battery system UNDER 200 pounds, with a "charge to full" feature of less than 12 hours.
It was costly, around $14,000 but to a person who owns a million dollar home, $14K doesn't seem like all that much money. I'll see if I can get the company info, if nothing else - it is good reading!!!