One of the frequent criticisms of wind energy is that national distribution systems (`the grid') cannot cope with large number of turbines because of the variability and unpredictability of their output. Grids need to match supply and demand precisely, the critics say, and because wind varies so much it causes huge problems. Recent data from two meteorologically unusual days in Spain - the world leader in the management of renewable energy supplies - shows this assertion is almost certainly false.

• During part of 8 November, Spain saw over 50% of its electricity come from turbines as an Atlantic depression swept over the country's wind parks. (They are so big that no one seems to call them `farms'.) Unlike similar times in November 2008, when Spanish turbines were disconnected because the grid had an excess of electricity, the system accepted and used all the wind power that was offered to it.
• A very different event in January of this year saw unexpectedly high winds shut down most of the country's turbines with little warning. The grid coped with this untoward incident as well. These two events show that a well run transmission system can cope with extreme and unexpected events even with a large fraction of power provided by wind.

Over the course of this year Spain will generate about 14% of its total electricity from wind and this number is likely to rise to the high twenties by 2020. Spain is showing the rest of the world that these figures are not incompatible with grid stability. Although wind is `variable', `intermittent' and `unpredictable', a well functioning grid system can still use wind to help stabilise electricity costs, reduce carbon emissions and improve energy security.(continues)