Comment Re:Boom. (Score 1) 325
The main reason why a week's energy storage would be needed is if a large fraction of the electric energy production came from wind turbines (this could be either an isolated electric grid or a customer contracted with a wind energy company). It isn't unusual for calm periods to last several days and unfortunately for those relying on electric heat, those calm periods can be the coldest days of the year.
Speaking of wind - it would make a lot of sense to have batteries that would handle one to four hours of household use, provided that the batteries could take numerous charge/discharge cycles and had a reasonable cycle efficiency. Wind generation can have large variations in output over short time periods, which stresses the grid as most generation does not like rapid variations in demand (exception being hydro). A smart grid plus household batteries would allow the load to track variations in generation as opposed to generation tracking variations in load.