Curious as I have not checked geo data in your area but can you not just go deeper for a good geo loop? What is the ground water temp on average?
Also, IIRC, the wind blows there? I guess if you have other heat sources, wind might be too costly but that can work well to simply dump all wind genny heat to a resistive heater for radiant heating.
I also plan to cool the slab in summer too. I hate to use the term "radiant cooling" because we know that won't really work but I want to remove extra heat gained by the slab from surrounding hot soil. I have learned that the slab can get to 90*. Just getting that back closer to dew point should significantly reduce cooling loads.
Yes, there does seem to be high winds in North Dakota TCM but, consequently, the wind thus contains a vast amount of energy and it is a shame, in view of what you say, that that energy can't be tapped.The wind tears all but the most over built wind generators to bits here.
Don't think I am arguing, just interested. The sticky on the ETO section on renewable energy says the exact opposite. That is that horizontal turbines are the best approach. https://www.electro-tech-online.com/threads/wind-generators.94505/vertical axis or VAWT units hold the most promise for lower scale units.
A solar approach requires both storage batteries and inverters.battery backs are not cheap, etc, etc, etc.
To me the huge drawback of solar is that, by definition, solar can only be productive for 12 hours a day and then thre are clouds to worry about and the seasons.This starts making solar look much more appealing.
Thanks for info TCM: always illuminating to hear from people with practical experience.That added complexity for blade pitch control is the primary killer behind DIY wind power. The commercial stuff has it but they typically want 15 - 20X what a single unit costs to build which puts the realistic ROI so far away into practical.
The best and most reliable DIY wind generators I have ever built just use a single 2" x 6" carved to match the old 1930's wind charger and similar genset blades of that era. Dang hard to kill a 6' long hardwood 2" x 6" by spinning it! Still the service life here is about 4 - 5 years before the wood gets so wind scrubbed it losses all its aerodynamics.
I've tried many different supposedly commercial fiberglass blade sets over they years and everyone had at best a few months service life before they either just came apart or flew apart. Same with the last set of all metal blades I tried. Worked great for ~ 3 - $ months then stress cracked to bits and folded over one day.
I put up a 20' tower near my old house so that I can put a smaller wind generator up some time soon but until carve a new set of blades it's just gonna have to wait. I've got a 1500 watt PM three phase servo motor for the generator and the steel for the frame so that could go together at any time but I have other priorities now like my new mini used oil fired boiler I am putting together.
Thanks Erichi spec,
'tcm' has posted a lot of info over the years on wind generators, search his posts .
E
one link
https://www.electro-tech-online.com/posts/1089822/
While I appreciate an array of small propellers would not be as efficient as a single large propeller, is there any merit in this approach from the home constructor point of view?
I've mentioned before that I've built and deployed various Savonius rotor driven PM generators (not a big fan of propeller driven systems).
The biggest advantage I've observed is that they are omnidirectional, i.e., no need for a rotating base. They are also relatively immune to over speed problems and are pretty torque-y; they are frequently used for irrigation pumps and pond aeration. And, compared to prop types, remarkably easy to construct.
By "wing" do you mean "prop" types?How big were your wing generators? Do you have any links?
By "wing" do you mean "prop" types?
If so, only once tried to build that type - gave up pretty fast because of the degree of expertise (airfoil calcs) needed. By comparison, I could put together a (crude but working) Savonius from a 50 gallon oil drum (biggest I've made) in about an 2 hours. Smallest from a beer can.
Here's a pretty good example (not mine):
https://www.thebackshed.com/forum/forum_posts.asp?TID=889
I've been playing with wind power since my mid teens nearing 30 years ago now. The #1 problem I have ran into with the DIY or any other system in my area is durability of the blades.
Making a genset and frame that can take a beating is easy enough but finding a reasonable blade set that will take gusty winds with 70 - near 100 MPH peaks is not and around here if a wind generator is placed on a good hill using wind ramping effects makes hitting those wind speeds pretty easy.
My general approach has always been to build a unit with a generator systems that can keep a blade set loaded down to a reasonable RPM (just under supersonic tip speed is where I shoot for) in any wind we have which to be honest meant most of what I have ever built ended up being system with 6 foot rotors and 1000+ watt generators with nonlinear loading systems which in every case obviously that was not enough to hold things together.
For my preference I have never been one to try and get energy from light winds and have always designed for high output hammer down winds for my energy production. I don't consider anything under 10 MPH worth going after for any realistic power production numbers. Doable but not a primary design goal. Why bother going after 500 - 1000 WH a day production on light winds when a good high wind day here can do 20 - 30 times that?
I don't bother with hanging out on the AE forums anymore given there at too many goons who need to take the OCD pills and step into reality over what it is they are working with and toward for what level of realistic time, money and effort they are investing.
To me it makes no sense to spend 10's hours on designing and making a blade set to get X amount of power from say a 6 foot rotor in a 15 MPH wind when a less efficient but far simpler, cheaper, more durable and far faster to manufacture (< 3 hours from a common size board) design can put out the same power if you made it 6.5 feet long.
But that's just me.
But isn't it a simple matter to limit the blade tip speed to any value you like. This is the bit I do not understand.
That sounds like an interesting approach Mike. I had similar thoughts. So you can get fully feathered props from what you say. What sort of weight are your props?This thread got me thinking about a couple of retired aircraft propellers I have sitting around here... If I mounted these on a tower as a giant wind-driven piece of yard-art using a DC generator as a dynamic brake, would they produce any usable power?
One is a fixed-pitch, two-blade, 74inch tip to tip, solid aluminum prop from a Cessna 172. Tipping this one up would be the only way to stop it. Dynamic braking could slow it down...
The other is a variable-pitch, two-blade, 82inch tip to tip, solid aluminum prop from a Cessna 182. It is used as a constant-speed prop (meaning that a servo senses the engine crankshaft rpm and the blade pitch is automatically adjusted, varying the load on the engine, to keep the rpm constant). Varying oil pressure (0 to ~ 50psi) inside the prop hub is what actuates (using pistons/springs/gears) the angle of attack of the prop blades. Unfortunately, this is not a full-feathering prop; the blades rotate about 40degrees.
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