Readers letters
I would suggest that the 65% thinking that more off-shore wind is a good idea should read-up some meteorology, some aerodynamics, and some electricity supply actualité.
We get many anticyclonic spells affecting the UK for periods from a day to a fortnight. There have been ten so far this year. The big ones can be very big, engulfing Ireland to Moscow, Scandinavia into the Sahara. The widely spaced isobars, like contours, indicate a gentle gradient, but of atmospheric pressure, not terrain. Atmospheric pressure is the main driving force behind wind.
Over land, the turbulence due to terrain, tower blocks and trees impedes the airflow, so speeds are lower than over the oceans. When it is “Near Gale”, Force 7 over the sea, off-shore turbines will be developing full power, and on-shore machines will be doing appreciably less. But when it is Force 3 off-shore, it can’t get much slower on-shore. They’ll all be producing very little. On one of my early studies of Germany, in 2009, on 27th Jan their 23,196MW wind fleet was below 100MW for most of the day, and clocked just one MW at 3pm.
Doubting, I looked at Denmark’s archive, www.emd.dk/el (do try it) and their 3,200MW fleet was producing 6MW at 3pm, 4MW at 9am. On a number of occasions in that anticyclone it was actually clocking some minus figures. The machines have weathercocks to determine the wind direction, and they activate electric yaw motors to keep the machine pointing the right way. When winds are “light and variable”, they are moving this way and that all the time, but generating nothing.
At that time UK winds at our six dozen Met Office observation sites, (with a mark-up of 20%, tall turbines short anemometers), were good for about 3% of installed capacity.
Do look at our Met Office Surface Pressure charts, and the NETA site www.bmreports.com/bsp/bsp_home.htm. On the latter, go to the Generation Mix chart, click on the Current/Historic cartouche, then on CSV to get the 3month archive of half-hourly readings. Lastly, to see what pumped storage is costing us, look at National Grid Real Time, Demand data.
Waves, tides and solar all have similar stories – unfortunately the problems of renewables lie in the Earth’s shape, rotation, axial tilt, orbit, its weather, and the orbit of its Moon. And, of course, the laws of physics. None of these are amenable to development.
Economics come into it too. We have to build something reliable to provide security of supply in winter anticyclones. But that something will be deprived of sales whenever renewables do function. So as well as subsiding the renewables, we will need to subsidise the others too.
I'm not barmy, let me out!
Bill Hyde, Offham, Kent
Next letter: The bombs keep bouncing