Wind Energy for the National Grid?

Government statements about wind energy being able to supply a large fraction of our electricity (via the National Grid) are optimistic. Wind can only go a small way towards helping our problems.

The National Grid system which currently distributes electrical energy to satisfy the base load requirementsof the country needs a constant and uniform energy input from its feeder power stations. Until now this has been supplied by coal, gas and nuclear.

Grid control staff know the base load requirements for a typical day and they arrange for the necessary power stations to be available to provide this power.

This planning has to be done in advance as large steam generating sets cannot be started from cold and put under load quickly. They need to have their temperature raised slowly over a significant number of hours before they can have electrical loads imposed on them.

It is interesting to see the electrical demand on the national grid as it occurs. One can actually get an impression of the TV programmes the nation is watching by noticing the sudden demand for additional energy as the electric kettles are switched on when the adverts appear on the commercial channels.

So ... the grid staff know the base load requirements for a typical day. They keep what is called a "spinning reserve" available to deal with sudden variations in demand. "Spinning reserve" means that a number of steam turbines are kept in a hot and spinning state of readiness, so they are in a position to accept load very quickly. In this spinning state (the most inefficient way in which a turbine can be run) they are supplying no power at all. Because this is extremely expensive, the spinning reserve capacity is judged carefully and maintained at the lowest level possible.

The problem with using wind synchronised with the national grid is that it is unpredictable. This means that a much larger spinning reserve will be necessary for when the wind stops blowing. To include it in the base load programme assumptions for the next day is very risky - the BBC weather forecasts only get their predictions right about 50% of the time.

Perhaps a more sensible approach to the use of wind energy for people in suitable locations would be to install a wind turbine complete with inverter and batteries. In this way they can be independent of the grid unless they require significant amounts of energy for cooking, washing, or when the wind is not blowing sufficiently for long periods. Such use would not need subsidy.

Nigel Deacon / Habitat21 website

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