T. Boone Pickens’ * real investments are in candle futures;

E.on is Germany’s largest utility company. Here is their 2005 Wind Report in pdf. I would recommend to everyone to read it. Sometimes they can use the wind power and sometimes they can’t, and because their effective usage is so low, they have to keep building traditional power plants. In 2004 the average feed-in to the grid varied between about one third and zero percent of the load. Obviously that sort of performance places upper limits on usage. I quote:

As wind power capacity rises, the lower availability of the wind farms determines the reliability of the system as a whole to an ever increasing extent. Consequently the greater reliability of traditional power stations becomes increasingly eclipsed.
As a result, the relative contribution of wind power to the guaranteed capacity of our supply system up to the year 2020 will fall continuously to around 4% (FIGURE 7). In concrete terms, this means that in 2020, with a forecast wind power capacity of over 48,000MW (Source: dena grid study), 2,000MW of traditional power production can be replaced by these wind farms.

The rest of the report comments on the grid problems and the need for specialized control of wind turbines, plus upgrade of the transmission lines and grid to deal with the pulsing of wind power. They have invested in programs to predict and control it, but they haven’t produced much effect. Now they are looking to replace the older turbines with newer, taller ones and to move offshore for more reliable winds. At the end of the report they discuss the potential for grid instability, and cheerfully note that if they are not careful, they may blow up pieces of the Polish, Netherlands and Czech power supply.

Apparently, all those pesky engineers who hang out* around here are right!
(Lots more at the link.)