The point made by some engineers, that 1.5 kW is too low a value when predicting the number of houses supplied by a wind turbine, should not be dismissed lightly, as the misuse of this statistic hides a multitude of sins.
With an average consumption of 1.5kW, the 20 million UK homes would require an electricity supply of 30,000 MW which is about correct, but that is only part of the picture when evaluating wind power. Since electricity has to be generated the instant that is it needed, the value is meaningless unless the 1.5 kW can be generated to match consumer demand. This is frequently not the case with turbine load factors of circa 20%.
The essence of understanding electricity supply and particularly the damaging consequences of a high renewables penetration, is the diurnal power demand graph and the annual load/demand curve. The latter reveals the duration of power demand through the year.
There is a plateau of 40% that has to be met 8760 hours per annum, but the remaining 60% has to be met by flexible power plants, adjusting continuously to maintain system frequency and power quality.
Wind power is incapable of meeting this requirement. More seriously, wind, wave and solar plants invariably give their minimum output close to periods of maximum demand 6 pm on a freezing night in January and being a variable negative demand in the distribution network are a destabilising factor during periods of unsettled weather.
