Storage and recovery makes sense

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Whenever some critical resource is only available intermittently, the typical response is to store it. Food, water, and fuel represent excellent examples of storable commodities. Electricity is not so easy to store inexpensively and efficiently and this has led to the general view electricity storage is not viable. Where electricity may be supplied from numerous sources via numerous interconnectors, as in Europe, the question of storage is not at the top of transmission engineers' priorities. But there are many areas of the world which have neither the dispersed generation nor multiple redundant distribution capacity enjoyed by the EU.

Australia is a good example where electricity generation and usage tends to be highly concentrated into specific areas, with large distances between them. A small number of interconnectors then connect the areas together. Furthermore, a large proportion of electricity is generated from base load coal fired power plants; peaking plants tend to be natural gas. Under hot weather conditions, the interconnectors tend to operate at or very close to maximum capacity for substantial fractions of the day. Should any major generator falter and be unable to dispatch power during peak loads, the interconnectors will overload, compelling immediate load shedding to preserve stability.

Wind alone is not the answer under such circumstances. There is a definite negative correlation between the availability of wind and the peak loads -- people tend to feel more uncomfortable and operate their air conditioners when wind speeds are low. One way in which wind energy can be used under these conditions is to store and recover it during periods of high demand. Storing electricity and recovering it is economically equivalent to generating electricity from electricity. The recovery process thus increases the electricity cost, even if the storage system were totally free -- which it will certainly not be.

A possible solution to this dilemma employs a dual function store, which possesses an alternative role of such value that its cost is largely recovered elsewhere. This constrains the choice of store considerably. One attractive implementation uses electric vehicles which can connect bidirectionally to the grid, storing surplus energy when it is plentiful and recovering it when prices rise. Because the vehicles are financed as vehicles -- and not as energy stores -- their costs are not borne by the industry. It is hoped that a trial of this technology and the supporting financial infrastructure can be commenced in the near future.

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