Thursday, 27 May 2010

Exploring an onshore wind farm

There was a lot of discussion last week about the merits of offshore renewables, following the launch of "The Offshore Valuation", the latest report from the Public Interest Research Centre.

I agree with their findings but not with some of the interpretations of this report in the press. For example, George Monbiot argued that this work shows that onshore wind is not worthwhile in comparison with offshore wind, wave and tidal power.

Last week, I took the train from King's Cross to Aberdeen to visit the Centrica's 20-turbine wind farm in the Glens of Foudland, near Huntly. The airports were closed that morning by volcanic ash so there wasn't a spare seat to be had on the train. The plus side was that the emissions per passenger-kilometre were absolutely minimal on this journey. Actually, I was pretty confident that, during April and May, Eyjafjallajokull was responsible for more carbon emissions reductions than the wind farm I was visiting - but that's not a popular sentiment amongst our erstwhile-airborne friends and colleagues. I have to confess that the return journey, with about 30% occupancy on the train, was a lot more comfortable.

The windfarm was commissioned in April 2005 and is ideally situated at an altitude of 330m on rocky hills set in a wide, windy valley. Because of this situation, it has achieved a consistently high load factor (ie., proportion of its theoretical peak output) throughout its 5 years of operation. It is now reaching the end of its manufacturer's warranty period so there were several engineers on site, checking each of the turbines for faults and preparing to change the gearbox oil (which, I was assured, is taken away for reconditioning and reuse). With the right build quality and the appropriate level of care, these turbines will continue to generate renewable energy from free fuel for a quarter of a century.

Wind turbines are very valuable assets and their components operate under extremely high stress - just imagine the weight of a turbine blade (which can now be up to 60 metres long) turning full circle every few seconds, bolted onto a steel shaft driving a generator through a huge gearbox on top of a hollow steel tube, in a highland gale.

Now picture the same construction glued onto another 100-metre pile driven into the seabed, battered by waves and corroded by salt spray. The maintenance challenges are much more extreme than for these onshore wind turbines but the access is unimaginably difficult and expensive. So, while I agree that the longterm prospects for renewable energy from Britain's offshore territories are superb, I am certain that we need to continue erecting onshore wind turbines in suitably windy locations across the country. Britain faces energy supplies issues from the middle of the current decade and we need to be working flat out to install do-able renewable energy technologies now, at the same time as we are developing next generation renewables for the future.

The other piece of the puzzle which was written up by Jamie Bull, one of the researchers for the PIRC report, but not developed within the report, is the return on energy invested in building and maintaining renewable energy assets. Along with tidal range schemes like the lagoons proposed as a alternative to the Severn barrage, wind turbines yield the greatest return on energy invested in their manufacture, installation and maintenance. They are about three times as efficient as solar electricity panels, for example. And that goes for both onshore and offshore wind installations. So let's keep putting more wind turbines in windy places, where the load factors will be as high as possible and where the ground won't be damaged (for example, installing wind turbines on peatland dries out the precious peat, causing large-scale methane and CO2 emissions) and let's get used to their visual impact. After all, we have covered the countryside with pylons and cables for distributing electricity - let's put up with these bigger pylons that actually make it, for free!

My thanks to British Gas, for covering the costs of my rail fare and accommodation for this visit, and to Matthew Walsh, the extremely knowledgeable and able manager in charge of the operation and maintenance of Centrica's wind farms. He's one of those unknown soldiers in the fight against climate change and I take my hat off to him.

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