The last few decades have been witness to a general trend of decentralisation leading to distributed networks in various areas including data processing, electrical power generation and electronic devices (e. g. mobile telephony and computing). It is also recognised that this trend will continue for the coming decades, as can be inferred for electrical power generation from a forecast made in Osaka by the International Energy Agency. This stated that non-hydroelectric renewable energy ‘will grow faster than any other primary energy source, at an average rate of 3.3% per year for the next 30 years’ [117].
One factor on which all these trends rely is storage, be it programs on the hard disk drive of a computer, water stored in a hydroelectric dam of an electricity network [259] or the electrochemical potential of the battery in a personal digital assistant (PDA).
A related parallel can also be seen between the technical needs of distributed electrical networks and those of electronic products. Both must cost effectively balance supply and demand of electrical energy-anon-trivial problem. A number of policies may be considered, including reducing or smoothing global energy requirements (consumption) as well as storing energy for later use, such as with batteries for ‘peak shaving’ (e. g. the 40MWh NiCd in California [50]). Typical IPV storage technologies are considered in section 6.6, while Figure 6.1 shows the breadth of electrical power storage technologies currently available.
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Figure 6.1 Simplified summary of electrical power storage technologies [144], reproduced with
permission (SMES = superconducting magnetic energy storage; NAS = sodium sulphur; UPS =
uninterruptible power system) from Elsevier
