Passage 14 completed prompting a muse on Wind Turbines

posted 16 May 2015, 15:45 by Dominic Thwaites
My passage 14 notes  details a nice fast passage to Whitehills in the Moray Firth where I stayed for 2 nights.  The second day was exploration day (afternoon actually) where the highlight was visiting the Boyndie centre that is based on a second world war air base (that flew bombing sorties on moored german ships in the Norwegian fjords). The place told you all about wartime operations. Fascinating stuff. You also got to see 8 wind turbines they've installed on the site. More fascinating stuff. 

Blimey, those bad boys are monstrous! Now I'm all for going green, but one thing I've always thought is that their costs must be out of proportion to what they earn. But this visit gave me some initial data to do some calculations. Here's what we've got. It cost £20m to install 8 wind turbines that have a peak output of 2,000kw. Now come my assumptions.

It's windy here, granted, but let's say they average 500kw per hour over the year. How much can they sell a kw for? Well, I buy them at about 15p per kwh. I have solar energy at home and they pay me 4p per kWh for exporting it. Point is most of the cost of electricity must be in distribution, margins and overheads. So let's assume that the power generated by these bad boys can be sold at 5p per kwh. So now we have 8*500*.05=£200ph revenue. There are 24*365 hours in a year so that's £1.75m per year. There must be an annual maintenance cost on the turbines - maybe £250k per year. So I get £1.5m revenue year on year. It cost £20m, so I reckon we're looking at 13 years payback. What's there shelf life? Who know's but I'm guessing 25 years.

So as it turns out, from my back-of-the-envelope calculations any banker would be happy to finance some long term debt based on this. So it makes sense. I change my mind. Unless someone with more than an acorn of knowledge about such matters can put me right!