I don't think that there are laws for energy storages. But I think the regulation depends on their usage. For example in Germany a electrical energy storage could either take part in the market or is used directly for the system operation. Maybe also the attached study of the Sandia National Laboratories could help you. It describes the market and policy barriers to enery storage deployment.
I think the use of storage tends to be integrated into other regulation, where it is covered at all. From the consumer side storage looks like generation so fits with the general licensing of generation. The use of storage on networks is a bit more complex, in the UK storage on networks would effectively be included in the new 'RIIO' regulation. It is too early to say whether this will lead to significant volumes of storage on the networks, whether there are sufficient incentives in this regulation and whether the economics will favour storage. The UK DNOs are experimenting with various storage set-ups through the Low Carbon Network Fund. The UK's Smart Grid Forum, which brings together industry, Government and other stakeholders discusses some of the issues relating to storage in chapter three in the linked document.
I'm not sure that too many countries have really given much consideration to things like storage (and its regulation) that will be needed in evolving electricity systems that have to deal with more intermittent generation.
Many thanks for your thoughts and the link. It's also my impression that we're just doing first steps in placing (in technical and regulatory terms) storage in the energy system. Also some Polish DNOs are interested in it. It's a good time to collect first experiences and do a research in this area. I suppose that in the nearest future we will face not only technical but also regulatory problems regarding e.g. V2G. By the way, I find British RIIO and LCNF very interesting example of modern and pro-innovative mode of regulation of energy networks.
Regarding Soft regulations... legal globalization is set up either on binding "classic" regulations and on the so-call soft-law, administrative practice and contractual links (i.e. see all of them applied by the World Bank activity among other prominent institutions and bodies). Although Montesquieu asserts are, of course, still recognized on the legal practices, there are currently enriched by other (almost) legal tools.
Not quite a “store of energy” but the thermoelectric plants in Brazil are activated only when energy consumption increases or when the rains fall (and decreases the production of hydroelectric). They work as a security measure to keep the national electric system running