The Unbroken Window: "So no responsible person would ever take the rated capacity of each turbine, multiply it by the number of turbines and then say that this is how much power available to homes. That’s just about as responsible as me saying that I know lighting will strike my home some day, and if/when it does it has enough energy in it for me to power my home forever."
'via Blog this'
4 comments:
Not saying I agree with all the subsidies for renewables, but I think it's completely fair to report the rated capacity of a wind farm. We do the exact same thing with all types of power plants. Granted a wind turbine is much more intermittent than a coal plant, but coal plants are very frequently producing less than their maximum capacity due to maintenance, outages, and off-peak hours.
The problem with reporting the wattage of any facility is that it is a rate. It's like reporting the top speed. The actual energy produced is a scalar quantity and depends on how fast you're going and for how long. When energy is reported for some reason the use the ridiculous unit of kW-hours (instead of joules or calories, actual energy units), which is akin to reporting a distance as mph-seconds.
The point is, estimating the actual output is generally confusing and unpredictable. It would be like selling a new car with a rating of how many total miles you'd get out of it.
Also, the company reported that 125 MW would power about 50,000 homes, which is half the number you'd get using the authors estimate of 2,000 homes per turbine. The company's number could very well be accurate.
You should comment on his blog and see if he responds.
I don't think the 2,000 number is the authors number. He writes:
"It installed 50 turbines, each rated to 2.5 megawatts (for comparison, you probably require between 1 and 1.5 kilowatts to power your home at any particular time, so 2.5 megawatts is theoretically large enough to power approximately 2,000 homes’ worth of “regular” electricity use – more on this in a minute)."
Maybe I'm reading this too quickly, but I think he's simply setting up their claim, not asserting this is the actual number. Later on he estimates the actual number of homes the turbines can power:
"So even a very optimistic outlook suggests that Cohocton Wind could produce about 37.5 megawatts of power, not 125 megawatts (assuming load factor of 30%) — enough to power 15,000 homes by their accounting."
Then he goes on to question the assumptions justifying that number.
His later number of 15,000 is even more confusing to me. He took a load factor of 30% (I'm guessing fairly randomly), then reduced the power output of 125 MW to 37.5 MW (fair enough) and the homes from 50,000 to 15,000. But the 50,000 the company reported was already taking into account that the fact that the turbines won't be running at 125 MW for 24 hours a day. So the author seems to be discounting the already discounted number.
Put another way, taking 2,000 homes per turbine at max output gives 100,000 homes. The company estimates 50% of that to get down to 50,000 homes. The author cuts this another 30% (down to 15,000), which in reality only assumes a 15% load factor. Maybe 50,000 is a bit high, but I'm guessing that 15,000 is swinging too far the other way.
I did comment on his blog, but it's still "awaiting moderation."
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