Monday, May 10, 2010

Big battery

I just caught a news item about a town in Texas which is building the world’s biggest battery. The intent is to maintain power supply when the single line from the national grid goes out – as it regularly does.
Now I don’t know how much wastage there is in storing power in this way, but the idea is great from a theoretical point of view. The normal pattern for electricity is for a central point of supply with failure prone transport to the point of usage. The risk of failure in transport is (usually) mitigated by using multiple redundant pathways – the electricity grid. This mechanism fails in the case mentioned in the article because there is only the single line into the town.
There are several known problems with the standard way that power is supplied. One of the biggest is that the grid is built around large scale centralised feed-in to the network and storage is apparently not practical at that scale. Hence electricity is generated to match demand – increasing production as more is drawn from the grid and dropping when usage falls. The possibility (probability) of under or over supply is obvious.
Balance is managed by using several sorts of power generation, at least some of which can quickly and easily brought on- or off-line. Even petrol powered generator may be included occasionally to meet short term peaks. At the other end, power is shed (read wasted) when supply outstrips demand.
In other words load balancing is done with methods which are quite expensive from both monetary and environmental points of view.
Storing (relatively) cheaply generated power during slack times and drawing against high demand would seem to make a great deal of sense. I assume that this is not possible at the national scale and so cannot be used in the central power plants. Given the fact that a town-sized battery is such big news, I guess that even storing at the sub-station level would be difficult.
But let’s take the concept further; how about power storage at the street or house level? Could each office building, which already have maintenance staff, include some electrical storage mechanism?
There may be maintenance concerns around having a bank of batteries behind the switch-board in every property – especially since traditional technologies use a number of toxic chemicals. But battery technologies have progressed fairly far in the last decade, riding on the back of the green movement and electric cars. At the same time the environmental and financial drivers for such a strategy are becoming stronger.
The idea ties in very well with the local generation of power. The input to the storage device need not be the national grid, it could just as easily be solar panels or a wind turbine placed on top of the house.

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