Friday, March 30, 2007

power pole microturbines

Made it to campus briefly to drop off paperwork. Now I'm back on the couch.

Through the screen door, I can see a utility pole, carrying the neighborhood's above-ground electric lines. I noticed that it's taller than most of the trees. And that the trees are blowing in the breeze. Hmm. There's wind up there.

I was wondering if it'd be useful to build a microturbine that could bolt to the top of a utility pole. It'd need to be auto-feathering to avoid blowing the pole over in high winds and would need an inverter and some other fancy electronics to match the phase of the power line, but if you had all that it could pump electricity directly into the grid whenever the wind blew, supplementing the main power plants.

After some back-of-the-envelope calculations, it turns out it's probably not worth the trouble. Let's use Del Mar, California as an example. They have (or maybe had) 184 utility poles and a population of 4389. That's 24 people per pole. The average Californian uses 7,000 kwh/yr of electricity (or 798 watts if you translate to civilized units), while the average American uses 12,000 kwh/yr, or 1368 watts. So the demand is 19,035 watts per pole in California, 32,631 watts/pole outside it. Windside's cute little micro-turbine, model 4C, produces 240 watts at a wind speed of 15 m/s (33 mph). But it looks like Del Mar's in a "marginal" wind power area with average speeds of around 13 mph at altitude. Assuming the turbine's output varies linearly with wind speed, bolting one to the pole should give you about 95 watts/pole. That's 0.5% of consumption per pole in California or 0.3% for the rest of the country. So you'd need a bigger or more efficient turbine, less energy consumption, or more poles to make a significant difference.

To bad, too--they'd look cute spinning up there.

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