UPDATE: See this link for update from the 4R Energy Corporation.
Many who oppose renewable energy point to its intermittent nature. While a transcontinental grid would address much of this, by averaging out sources, additional dispatchable storage will still be an important part of the SuperSmart Grid. And storage is generally expensive.
Several companies have come up with a promising solution to low cost storage. Use spent batteries from electric vehicles like the Nissan Leaf or the Tesla. As batteries age their capacity diminishes. For a car that translates to reduction in range. Typically they are retired when they still have 70% capacity. That is plenty to be useful in applications where the weight is not a critical factor. And it won’t be long before 100’s of thousands or even millions of battery packs will be looking for new homes each year. This translates to a scale of GWhr’s of storage added per year. This is of the appropriate scale that it can play an important role in utility grid storage.
Here is a paper, for technical people, that reports on endurance of Li-ion batteries.
Li-ion prices are dropping rapidly –
This company is deploying grid storage with Li-ion batteries.
V2G, EV Battery, Repurpose for grid