Monday, 17 February 2014

Gale force winds brings more clean power

We've been having rather a lot of weather lately - not just wet but also very windy - and I have been wondering how well our wind farms have been doing. Many detractors of wind power complain that when the wind is very strong wind turbines cut out to protect to prevent accidents. If so, you might expect wind farms to have supplied very little during the recent storms.  I found a handy website [1] which scrapes live National Grid data into a database you can query. The windiest period so far this year was in the first  week of January. Over that period, wind power supplied 13% of our electricity on average, double the figure from the same period last year.

The power available in the wind increases with the cube of the wind speed. That means if you double the wind speed the power increases times 8. However, wind turbines are usually optimised to produce reasonable power at normal wind speeds and the rotors would burn out if they took all the power available in a storm. The chart below shows a typical wind turbine power curve [2]. This one cuts in at 3 m/s and the power available increases rapidly until 12 m/s (27 mph) when it reaches its maximum capacity. After that, as the wind gets stronger the turbine protects itself, for example by feathering the blades, until it cuts out completely for safely at 25 m/s (60 mph).  We have seen gusts stronger than that in many places but that speed is very rarely maintained for any length of time.

Power/speed curve from http://www.vestas.com/
The windiest two weeks so far this year were the first week in January and the first week in February. The table below compares the wind power generated this year with the same period last year.  For the first week of the year the proportion of our electricity coming from wind was double the previous year and more than double the average for all of 2012 which was 5.6% [3].

Yearw/c Jan/1w/c Feb/1
Wind Mean  GW% of demandWind Mean GW% of demand
20143.4512.6%4.4911.3%
20132.366.2%3.428.3%


Some of the increase in wind power will have come from increased capacity but it is quite clear that our wind farms haven't failed us during the recent storms.



[1] UK National grid status www.gridwatch.templar.co.uk/
[2] V112-3.3MW from Vestas
[3] Digest of UK Energy Statistics (DUKES) 2013 ;

3 comments:

  1. Ironically, gridwatch is run by a climate change denier who frequently rants about the uselessness of wind power. See Usenet uk.diy passim.
    (Doesn't make it any less useful, of course.)

    ReplyDelete
  2. Not certain that gridwatch is run by a climate change denier, looks to be more concerned with demonstrating the problem of intermittency and the renewables/grid mismatch.
    I certainly encourage folk to read the resources cited on the Gridwatch page such as http://www.templar.co.uk/downloads/hughes-windpower.pdf and David MacKay's book 'Without Hot Air' free download at http://www.withouthotair.com/download.html.

    So far we have built some very excellent renewable energy collectors, but have as yet have no effective method of distributing the energy. To improve this situation we need to somehow build smart grids, but as technology stands this is years if not decades away.

    ReplyDelete
  3. The subsidies for renewables are far too high per KHW. Do away with these subsidies. The money is going into the pockets of big companies and land owners. Mr Bloggs and his wife have to pay for all this.

    ReplyDelete