Power generating in the real world
There have been numerous letters on the pros and cons of wind-powered generators.
Very few have discussed the real world of electricity generation.
The two most important things needed to generate the amount of electricity this country requires is brute force and good engineering.
We have adapted to an unlimited and reliable supply of electricity.
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When there are power cuts, it is very rarely due to the shortcomings of the power companies and nearly always to natural events or political will.
Few industries can match the dedication and success of the power stations to provide such a reliable supply, but it does come at a price.
Wind-powered generation has now entered the arena. The current figures for wind power output are that they generate some electricity for 80 per cent of the time with a capacity factor (not efficiency) of 24 per cent – 31 per cent the result of unstable wind and down time.
Although rare, we have already experienced one low wind speed period of seven consecutive days when wind power supplied less than 0.1 per cent of UK needs.
The opposite has occurred where it provided 10 per cent for a day.
Even the most ardent promoters of renewables accepts that to overcome this instability a backup is necessary. The only power generators that can meet the capacity are fossil/biomass burning and nuclear, with a tiny contribution from other renewables.
That's okay, say the greens, you turn them on only when needed, reducing CO2 by at least 30 per cent.
Wrong. If a steam-powered generator is needed to run within an hour it has to be kept on spinning reserve (standby).
The equivalent output of a couple of wind-powered generators is needed to run all the electrical services for the boiler and turbine.
There are two alternatives. One is to turn some units off – but then a restart under ideal conditions will take at least a day with a high risk of boiler tube failure.
The second is to run several generating units on part load. Seems ideal? Wrong again. All generators are designed to run most efficiently at maximum load or near to it.
If run on part load, the efficiency falls significantly.
The result of running part load is that fossil fuel is wasted to allow wind-powered generators to run.
Taking all these factors into account, wind power is hopefully a contribution but is certainly not a panacea.
We are lucky in the UK as we have relatively good wind conditions. Now wind power is established, investigations into its real contribution are possible. Early results suggest that the benefits are less than hoped.
In the USA, calculations suggest that in some states wind power is so disruptive more energy is wasted than it produces. Germany and Holland are reported to be neutral.
More research is needed. What is certain it is a very complicated issue with many variables, some controllable, some not.
In the UK, the result probably lies somewhere better than marginal.
Political posturing, profiteering on subsides and pressure group bandwagons are not helpful. Sound engineering is.
Clive Pearson, Glenfield.