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Old Apr 28, 2013, 10:46 PM
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Australia, VIC, Melbourne
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Originally Posted by mjsas View Post
Note: diode drop in a the full wave rectifier is 1.4 volts and batteries charge at 14.4 volts and discharge at 12 volts.
You need a better rectifier. It is not hard to get below 1V (or even below 0.5V) using schottky diodes.

Just because a motor is rated a 8kW does not mean you will get anything like that out of it. You would need to spin it at ~20kRPM to get that sort of power in any case, little difficult with a wind turbine.
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Old Apr 29, 2013, 10:11 PM
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Originally Posted by challenger_i View Post
That dog won't hunt. The hertz rate changes with genny rpm. Since a wind turbine generator doesn't, and can not, run at a constant rpm, you can not run a 60 htz appliance directly from the genny. This is why commercial WTG's convert the current from A/C to D/C back to A/C.
That is mostly true but an induction generator will put out a pure 60Hz independent of RPM under some conditions.
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Old May 01, 2013, 02:36 PM
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San Diego, CA
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I've been playing with a 2Meter, 1KW windmill that will turn about 150 RPMS. Consider the gears and gear losses involved in turning that into 20,000 RPM. Probably the biggest obstacle is...obstacles. The rule of thumb is 30 ft above the nearest obstacle within 300 ft. My property features a 75ft tall tree on the lot next door. The mounting pole for my windmill is thus prohibitive. Also windmills are practical in windy canyons where 10 to 20 knots is typical. 5 or 7 knots is more typical in city locales and not much good. Solar cells are a more practical method of home power generation and are getting cheaper by the day, < 1$/watt

V/R

Steve Manganelli aka Prof. Maneuver
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Old May 01, 2013, 03:04 PM
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746$ a HP . My house with 200A service than would need 32 HP to power it at full tilt so that =about $24,000 bucks for solar cells? Now we need storage battery's, (the cost to replace the battery's of a big boat now days (54 Hatteras) for my example which has 12D cells ) costing about $800 bucks apiece or so, that's about $10,000 in battery's. Now we need the regulator and inverter probably another $5 000to $10 ,000 depending on how fancy the gear is. Last but not least we need to pay all the building permits and all the mods to the roof to meet code (hurricane land) and finally someone has to install the gear. I would guess another $10,000. Wow that's allot of money for something that performance is severely diminished when a tropical storm hovers around for two weeks. So I'll need a genset during those periods, that is another 10 to15 K. and last but not least I get to pay a 6% sales tax. Let me check the ashtray in my car for some spare change.
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Old May 03, 2013, 03:12 AM
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United States, TX, Sweetwater
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Zero:
You can get a 10kw genny quite a bit cheaper than that. I'd recommend a diesel genny, as you can run it on a 50/50 diesel/waste oil (used engine oil, or used cooking oil) mix, to reduce costs, and can rig it to start on diesel, then run a 50/50 mix of diesel/ natural gas (the old "bifuel trick).

If you are coming off a battery bank, I'd recommend using a dedicated converter for each breaker circuit in your home. This way, if you pop a converter, you don't kill the whole house. These 15 amp (20 amp surge) converters can be had for about $200 each, and can be linked together.

I have seen a few off-grid systems that utilized a solar panel, a small (5kw) wind turbine, and a back-up fuel genny, to power small operations in remote locations. Pretty neat set-ups, that fit in a 8ft x 8ft shipping container. The container is achored securely, the turbine tower section is assembled and mounted on the aft end of the conex, and then is guy-braced on the lower third of the tower section.

You will still invest a chunk of change, to build a reliable rig, and, at $12 per kwh, it'll take a goodly amount of time to pay for itself.
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Old May 03, 2013, 09:07 PM
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maximum theoretical efficiency from a wind turbine is 57%. Derive it! :-)
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Old May 04, 2013, 06:13 PM
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Having spent 5 years working on wind turbines, I have found there is a great amount of difference between "theoretical" efficiency, and actual efficiency. I haven't seen one, yet, that made 57%.
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Old May 04, 2013, 09:28 PM
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Originally Posted by zeroback View Post
Interesting to note that windmills commercially produced for wind farms are outrageously expensive.... and they still don't work when the wind is not blowing.
But they can create wind when not in use. My design uses wind power to burn charcoal once lit by lighter fluid. The charcoal heated steam powers a blower for the forge to keep the wood burning as I constantly add it. Once the furnace is hot enough it will drive the blower, eliminating the need for fossil fuels. It will also power a windmill which will create a breeze to combat global warming, and drive other windmills giving them energy to supply their own breeze.
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Old May 05, 2013, 01:30 AM
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Ron:
Quite humorous! One item you mentioned was Global Warming. I once saw a report, generated by one of the organizations that constantly berate wind energy, that stated the proliferation of wind turbines being operated directly raised the atmospheric temperature, aggravating Global Warming. I nearly wet myself, laughing....
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Old May 05, 2013, 08:22 AM
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This is a topic I hold very dear and have done some minor experiments using a BL motor. So far, the best motors I have found for this applications are ones with a very low KV.

WindTurbine (0 min 59 sec)


WindTurbine - 450 Head Rotor Test (0 min 23 sec)
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Old May 10, 2013, 07:12 AM
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I have read that heavy duty automotive alternators make good windmill generators. You have to find your own blades, though.
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