Dear Editor:
It is awesome to hear that the students at Cochrane High are learning about sustainable energy, and that they even got David Suzuki to visit them.
It is great for social sciences education, it gives a warm fuzzy feeling to all the donors supporting the project, and it has a host of other tangible and intangible benefits, like local residents being able to get together and form the No Turbine in Town coalition.
Unfortunately, math and physics did not seem to be involved anywhere along the way. If anyone actually bothered to do a little math, they would have found out that, given the average wind of 4-5 miles-per-second (from Ms. Bennett’s presentation, and this number seems to be quite correct), the turbine would generate about 200-500W of power (from the Evance R9000 product certification document). The turbine would probably be running quite quietly at that wind speed.
The electricity produced would cost over $0.50/kWh ($25,000 capital cost, 20 years lifespan, $1,000/year maintenance). I guess they don’t teach any economics at Cochrane High either.
Now, every so often, a weather front moves through Cochrane, and winds in the 80km/h to 100km/h range are not uncommon (22-28 m/s). At those wind speeds, the turbine will become substantially noisier. How much noisier, we don't know — the manufacturer's noise table wisely ends at 11 m/s (40km/h) wind.
The residents concerned about the noise should get themselves a couple of noise metres, and on those windy days, and especially nights, take some measurements. If they find the noise to exceed the bylaw limits, the students will get a fat fine to pay, and after a few repeat offences, they will wisely take the turbine down.
Two questions left as an exercise for someone out there who understands a bit of physics and can do a bit of math:
1. What is the energy of a turbine blade spinning at 230 rpm or worse? (Hint: the tip is moving at 240 km/h, or 150 mph);
2. How many adult humans can be skewered by the blade with that much energy? Worse yet, how many kids?
One more question for those with legal aptitude: Who would be criminally responsible for the death(s) of people skewered? The students? The teacher? The school board? Nobody?
There is, however, another solution, which could please everyone involved. Mount the turbine lower to the ground, so it is less of an eyesore, and shorten the stator windings (the manufacturer’s fancy name for this is “electrobrake”). The turbine will still turn around, but only slowly, so not much noise will be produced. The students and teachers will still have a turbine to gaze at and to learn all about for long time to come. Whether the turbine generates nothing or 350W of energy does not really make a big difference.
I don’t live anywhere near the proposed turbine site, and it will not pollute my view either.
I also have a sales job to offer to Ms. Bennett. Her presentation is awesome, if not in substance, definitely in the form. I don’t think I could have delivered it keeping a straight face.
Jan Uttl
