Wednesday, September 24, 2008

Failure To Dylan

Joe Otten's useful heads-up on Caroline Lucas and the dogma of the Church of EnvironMentalism reminds me of something I meant to blog about a while back but left alone largely to avoid overloading the world with energy stuff.

We are often reminded how windy Britain is and how much potential there is meant to be for wind generation. Heck, one Lib Dem blogger (who I will refrain from naming in order to save a fellow elected member from having their name and moron too closely associated in Google) even went so far as to say;

“It's a myth that renewables cannot provide baseload. There has never been a day on record when the wind has not blown somewhere in the UK. The point about baseload is that what you need is enough people in enough places producing electricity. The more you decentralise electricity generation the more secure the baseload becomes. “

Interestingly, two weeks before that was said, a useful little study of the actual potential of wind generation in Britain was published. Okay, most of you probably weren't reading The Telegraph when it was covered, but I would hope my constant plugs have started to focus everyone's minds on The Register, a far more sound source of technology news.

As our anonymous blogger rightly identifies, the great problem for wind has always been the difficult question of variability; that sooner or later, the wind will stop blowing. We as Lib Dems have never really worried about this because the answer, we're told, is our favourite word; decentralisation. Indeed, some have proposed that large scale wind investment should be accompanied by the establishment of a Europe-wide electricity grid, so that the areas with the best wind at any moment can sort everyone else out.

The study uses the existing Met Office wind speed database, as measured at weather stations across the country, to evaluate the nationwide wind potential over the decade from 1996 to 2005. In general terms, it finds the system susceptible to “large, rapid and frequent changes of power output.” Hardly the best of starts, but nothing like as bad as things get when we consider the extremes of Britain's energy needs.

Excluding specific events like deaths on Coronation Street and England reaching the semi-final of anything, the annual peak of electricity demand generally occurs on the coldest evening of the winter between five and six pm, as domestic demand rises after the school run faster than commercial demand tails off at close of business.

You might expect that the coldest events are associated with Arctic or Siberian winds blowing cold air into the country. What the report finds, however, is that the coldest period in any British winter occurs when a high pressure system takes up residency over the country for a period of days; the absence of cloud to insulate the nation being far more potent when it lasts for five days or more.

More importantly, however, high pressure systems not only bring no cloud, but no wind either. Perhaps the most shocking finding of the report is this; between five and six pm on February 2nd, 2006 (the peak of the electricity demand that year) the total electricity output of the UK's wind turbines was less than zero, as demand from auxiliary systems in the turbines exceeded their output. And that isn't a number from the model; it's the actual result as measured by the National Grid! What's more, such examples really aren't unusual; a five day high pressure, low wind cold snap is an annual occurrence in the UK, while a ten day low wind cold snap is probably a once in twenty year event.

As for the Europe-wide grid, the report compared their modelled wind load factor for the UK against the large existing wind farm system in Germany and Denmark;

I'm sure you don't need my help reading that graph.

The message remains as clear as it has always been; the question of our future energy supply is absolutely not intuitive and it cannot be answered by reference to bland and uninformed generalisations. There is no issue for which that old chestnut the “informed debate” is more vital.

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