Wind farms are expensive and will not stop massive blackouts

To say that windmills work 90% of the time, as Kerr MacGregor of Scottish Solar does (January 13), is true but misleading. The amount of power produced varies roughly with the cube of windspeed up to the optimum of about 24mph. Thus a 6mph wind does indeed produce electricity, but only about 1/64th of capacity, which will not keep many lights on. This is why windmills overall produce about 27% of their rated power performance. Whenever you see another politician saying that such and such new wind farm will produce power for 50,000 people, it won't. Even with "planned downtime" - which, being planned, can be set for when demand is low - conventional generators are vastly more reliable.