You need to look beyond battery technology for the kind of storage necessary for the commercial grid. My point is that none of this is being done. My other discussion about batteries and submarines was to point out that when you can't get power (you're 30 mi from the nearest transmission line or 1,000' down in the ocean) there are alternatives available, people do use them, but they are not cheap, and there are obviously drawbacks. To Space's idea about central power being more efficient: it is. A central electric generating station runs at about 30 - 33% efficiency and it is possible to move this up into the 50% range with co-generation. Your average auto engine is lucky to achieve 20% efficiency.