I am no fan of wind energy. It is hugely over-rated. But, like most energy sources, it has its place. To dismiss it or condemn it out-of-hand is as distorted a view as to hail it as the solution to all our energy problems.
The Times today printed a damning article on an urban wind installation. A turbine installed four weeks ago at the home of Mr John Large, it reports, "has so far generated four kilowatts of electricity", compared to an average household's consumption of "23kw every day", and offering a return of "9p a week" compared to the £13,000 that Mr Large spent on the installation.
As many were quick to point out in comments on the article at The Times's website, and on many blogs, the journalist's ignorance of basic energy and engineering was revealed by his use of terminology. Kilowatts (or kW - lower-case k, upper-case W) are a measure of potential - the capability to deliver a given amount of energy in a given time if working at full load. Kilowatt-hours (kWh - as above, plus lower-case h) are a measure of energy - specifically the amount of energy produced if an engine with the potential to produce 1 kW is run at full load continuously for one hour. The phrase "has so far generated four kilowatts" is therefore a nonsense - kW contain no notion of time, so one cannot say that any number of kW have been generated "so far".
"23kw every day" is likewise wrong, not only in the spelling, but also in fact - to the extent that averages are in any way meaningful (which is a very limited extent), the figure should be 23 kWh, not 23 kW. 23 kW every day would, according to the best interpretation one could put on it (23 kW of demand continuously for 24 hours) equate to 552 kWh per day, which is way over the top. As it is, even 23 kWh per day is excessive - total domestic consumption of electricity in the UK is around 115 TWh (1 TWh = 1 billion kWh) each year, which is equivalent to around 4,800 kWh per household annually (there are just over 24 million households in the UK), or 13 kWh per household per day.