cubism kills the turbine

The last post on wind energy - for now.

I was still stuck with the thought that something is better than nothing and if you could use a turbine to power a few light bulbs or a laptop then at least that's something. And, I thought, it's not the technology that's crooked, it's the economics - they cost too damn much! Around £10,000 even after an improvement grant. Then the cost analyser in me wondered where this money was going - surely, a competent DIY person could make one from parts? Maybe there are blueprints!

Googling around a bit I found there are. However, then I stumbled upon this. And this. And, eventually, this.

Of course, the engineer in me knew there'd be an equation for it, even if it's merely rule-of-thumb. Apparently, it is,

Power in watts = (collection area in square feet) x (wind speed)3 x (0.0054)

or simply, Power is proportional to wind speed cubed. As it explains, turbines are sold on their ability to generate a nominal amount in windy conditions. But on less windy days - in other words, average conditions - the power drops disproportionally. Hence, half the rated speed results in just one-eighth of the rated power.