Year ago when I was a lad batteries were either massive lead/acid secondary designs. These had limited storage density and peak flows plus there was always the dangers associated with these heavy vats of sulphuric acid – but they did power milk floats (Qv)! Alternatively, for the torch there was the puny primary zinc-carbon design prone to caustic leakage and thus significant damage as the zinc (negative) casing “corroded” away!
Capacity (MJ/L) litre has increased by a order of magnitude (plus) and the battery has become much more “demand flexible” and controllable. It is now becoming feasible to propose distributed power storage on a building-by-building basis; which, together with smart-meters throughout the grid must make more sense than pumping water uphill (eg the Dinorwig & Frestiniog schemes) operating rapidly start gas-powered stations as a “spinning reserve” both of which are currently used to smooth out the peaks and troughs of electrical supply and demand. Localised chemical batteries are also “instantaneously” switchable rather than the 4-16 seconds required to start/stop for mechanical storage solutions. See: http://www.technologyreview.com/news/506776/a-startups-smart-batteries-reduce-buildings-electric-bills/?utm_campaign=newsletters&utm_source=newsletter-daily-all&utm_medium=email&utm_content=20121106 [6/11/12]
supplemental – better battery designs for vehicles… but not just yet! http://www.technologyreview.com/news/506881/how-improved-batteries-will-make-electric-vehicles-competitive/?utm_campaign=newsletters&utm_source=newsletter-daily-all&utm_medium=email&utm_content=20121109 [9/11/12]