H – Homes Powered

Exaggerated claims are frequently made about the number of homes that a wind plant can power or serve. As an example, it is often stated in the media that the 200 megawatt Wolfe Island wind plant could power a city the size of Kingston, Ontario, or 75,000 homes. This is not the case, and the information provided here can be used wherever this issue arises.

To power a home it is reasonable to require that a home’s peak demand be met, not just the average energy consumed (kilowatt-hours) over a year, a month or a day. The Ontario Power Authority assumes that wind power has an effective capacity of 21 per cent (percentage of power capacity, kilowatts or megawatts, to meet peak total system peak demand), which is generous. It is less than 10 per cent in mature and extensive implementations in Europe. Assuming an average of 2 kilowatts (not kilowatt-hours) peak demand per household and 10 percent effective capacity, the number of households powered is 20,000 kilowatts (that is 200 megawatts x 1,000 x 0.10) divided by 2 kilowatts per home, or only 10,000 homes, which is a far cry from the very questionable 75,000.

However, during periods when the wind is not blowing, or even at low wind speeds, no homes are powered, and if these homes were dependent solely on wind, they would be without electricity, sometimes for days. So, arguably no homes, not even 10,000, are really “powered” by wind plants.

Fortunately for these homes, Ontario Power Generation will be shadowing the wind production with gas turbine generators to ensure a steady supply of the required power. So, are the wind plants not really contributing, when operating? This brings us back to the consideration of the kilowatt-hours being delivered. The problem now becomes not just wind power’s low power capacity, but wind’s frequent, random and sometimes large fluctuations between zero and full capacity on a continuous basis. As well, there are many minor fluctuations in between these two extremes. This means that the gas turbine plant is stressed in having to mirror wind’s irregular behaviour. In this mode, the gas turbine plants are still operating 80 per cent of the time, but in doing so, consume at least 10-15 per cent more fossil fuel than when operating in the normal more continuous mode for the same amount of smooth production time. There will be an increased need for the more responsive, but less efficient, Simple Cycle Gas Turbines, which further increases fuel consumption. As well, the CO2 emissions produced by the gas turbine are 2 to 3 times the percentage loss in efficiency, depending upon gas turbine type, which can easily offset any gains made by the wind plant that is producing, but very erratically, only 20 per cent of the time.

The 80/20 split between gas and wind production is the general experience for extensive, mature installations of wind plants. As wind plant numbers increase, the better sites are taken up first. Also, wear and tear (the blade/hub assembly and nacelle on top of the 200 foot, or higher, tower weigh about 80 tons, or more than an Abrams battle tank) and contamination on the turbine blades can severely impact performance over time. Further, because of the problems that occur during periods of high production, curtailment (that is, shutting down wind turbines) is becoming a necessary practice.

So, if the purpose of having wind plants is to save fossil fuel consumption and reduce CO2 emissions, they do not achieve this when integrated into an electricity system. The gas turbine plants operating alone would provide the total reliable energy to power the homes, with no increase in fossil fuel consumption, but with arguably greater reduction in CO2 emissions. The wind plant capacity is unnecessary.

Last updated March 14, 2009

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2 Comments »

  1. Craig Goodrich said

    Good God, are they really planning to vandalize Wolfe Island? The Thousand Islands is my favorite part of the planet, a scenic joy. Hundred-meter industrial towers are not part of the deal.

  2. Your special dedication to passing the solution all around appeared to be certainly interesting and has truly empowered regular people just like me to realize their ambitions.

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