Great video, Charlie V. provides an evenhanded presentation on various storage markets and technologies while representing well the A123 technology. Thanks to Stephen for good questions and leading the discussion. As a representative for the VRB(tm)flow battery, my one complaint is the comments on flow batteries and efficiency.

A123 achieves 90% efficiency by operating within a very narrow range of their capacity in order to provide frequency regulation. This is appropriate for the application, but it is a capacity service, not an energy use. In other words, the value is in the quick pulse of capacity and very little energy is used, less than 15 minutes out of around 4 - 6 hours possible. Any battery, including lead acid or the VRB, can achieve the same efficiency as the lithium systems if they operate within a fraction of the middle of their depth of discharge.

However, one of the benefits of the VRB flow battery is the extensive cycling and hours of energy that are available. No other battery can cycle as many times as a VRB flow battery, last as long and provide hours of storage. However, if you utilize the full depth of discharge, for example 6 - 8 hours of energy, then you will see efficiencies around 70%. Contrary to the opinion of IDC Energy Insights, that does not "completely devastate the business proposition" - because that is the efficiency of hydro and pumped storage! According to Mr. Jaffe and Mr. Lacey, these systems "waste" energy and are "non-starters".

The key is the application, and there are appropriate applications for lithium, VRB, thermal, hydro, etc..