Re Andrew Bray's letter on power bills, Andrew needs to take a step back from his visually polluting windmills and think about his statements relative to the national electricity grid security.
Because wind is unpredictable and variable, the grid operator needs to keep spinning reserve available (normally open circuit gas fired generation) to meet load requirements each minute.
As the Productivity Commission estimated in 2011,for a megawatt hour of energy supply wind power came in at $150-$214, gas fired power at $97, coal at $78-$91.
As well, the commission estimates the subsidy to wind power is $40-$60 per megawatt hour.
That report does not seem to justify Andrew's claim of wind power generating electricity cheaper than coal.
Additionally, I suggest Andrew read Professor Gordon Hughes' submission in August this year to the House of Commons Energy and Climate Change Committee wherein he concludes that increases of 40 to 60 per cent are likely in household electricity bills by 2020 if wind generation is continued compared to a base line generation by Combined Cycle Gas Turbine machines scenario.
Prof Hughes adds "The key problem with current policies for wind power are simple. They require huge commitment of investment to a technology that is not very green, in the sense of saving a lot of CO2, but which is certainly very expensive and inflexible.
"Unless the current government scales back its commitment to wind power very substantially, its policy will be worse than a mistake, it will be a blunder."