Truth can sometimes be an elusive concept, but in this case, it seems to me that it’s possible for both sides to be right. However, they’re not talking about the same thing, and therefore one side being right about one thing does nothing to prove the other wrong about something quite different.
One of the arguments about wind is its predictability (or rather lack thereof). But it isn’t quite as simple as that – wind is quite predictable in the very short term and in the long term; it’s in between that it becomes unpredictable. Ask a meteorologist what the wind is going to do in the next hour or two, and (s)he will give you a pretty accurate prediction. Ask how much wind we’ll get over a year, and you’ll get another pretty accurate prediction. But ask what the wind speed and direction will be at 2.30 on the afternoon of Tuesday 4th September, and you’ll be lucky to get any sort of prediction at all.
The overall predictability of the UK’s wind and weather means that it is perfectly possible to predict with a high degree of confidence how many kwh of electricity can be generated by any wind turbine over a year. And whilst one may quibble with the detail of the mathematics (see MH’s post), converting that into a proportion of Wales’ total annual need, or even a number of homes whose needs can be met, is just simple arithmetic. So the claim put forward by those behind Gwynt y Môr is entirely reasonable.
The counter claim by the opponents is based on the proposition that the energy produced may not be available at the time required by those households, and at other times electricity will be produced which those households cannot use. It means that at times of surplus, the electricity produced will be used elsewhere, and at times of deficit, those households will be using electricity produced from other sources. So, the argument goes, those households cannot rely on Gwynt y Môr to supply their needs.
That’s also true, but the proposition it demolishes isn’t the one being made; it’s something completely different. And it certainly doesn’t support the conclusion that wind is therefore a useless source of energy.
Given the starting point of this post, I’ve only referred to wind, but we can actually generalise from that. Any type of electricity generation based entirely on (free, unlimited) natural renewables (whether wind, tidal, solar, hydro or whatever) will never be able to match the certainty of availability when required which can be obtained from a power station fed by (expensive and depletable) fuels.
That isn’t an argument for sticking with fossil fuels, nor for rejecting the use of renewables; it's just a feature of a different apporach to energy policy. What it tells us is that, if we want to use emission-free renewables, we have to think in different ways about our electricity supply and distribution infrastructure. Up to a certain percentage – as I recall, National Grid figures suggest that to be around 20% – the impact on security of supply is fairly minimal and can be coped with more or less within existing backup and contingency arrangements. Beyond that, we will undoubtedly need to look at ‘storage’ facilities. In addition to that, grid interlinks which spread the risk over a wider area are already being built.
We can’t – and no-one is suggesting that we can – rely on wind for all our electricity needs, but we can and should use it as part of the overall mix.