The majority of different commercial energy storage systems rely on chemical reactions. The same issues are in this energy storage as in all energy sources – energy produced/weight of source, efficiency and duration available.
However, so far with current technology this article in Green Tech Media points out that development of energy storage suffers in all three categories.
Nothing, even major government investment will change this fact. If a breakthrough occurs with our current economic system, major financial renumeration will be the result. Unfortunately a national energy policy is not going to help the development of a viable energy storage system but might probably result in a waste of taxpayers dollars. This article does supply a good review of the many energy systems that are available.