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I got to talking with a fellow who owns a vineyard recently over a beer at lunch in a neighbouring town. After helping him figure out how to keep bears from coming down out of the hills and eating his grapes the conversation turned to power requirements and I mentioned how I would like to someday
farm electricity and sell it back to the grid wholesale. It turns out that this has just become an option here if you are hooked up to their Smart Meter system. Any power you produce over and above your usage becomes a cheque rather than a bill but only if the energy is produced by "green" methods.
I told him about this video I had seen from somewhere in the Netherlands about a four story chimney in the center of four acres of shade cloth that turned a turbine 24/7 due to the temperature inversion, (can't find the video any more...) and he asked if I could help him set up something like this on part of his property he wants to develop next year.
It's more than a bit outside of my comfort zone, but I told him I would try to find and print off the information he'd need and go from there.
Wading back into this solar updraft tower power generation thing got me to thinking about ways to shrink the system so to get more power from less room. Four acres is a lot of space most people don't have at their disposal.
I figured out ways to amplify and store the heat so it would continue to leech out at night when the cold air would make the miniscule saved heat as effective as full sunlight.
I figured out ways to shrink the tower while improving its efficiency by using solar heat to inflate the structure using the interference of a three dimensional tubular Tesla valve tower of decreasing diameter.
In the end I settled on a simple few centimeters deep 2D tesla valve table top, painted black with a clear plexi-glass surface. When the sun shines, the expansion of air causes it to escape and the air has no choice but to move in the direction chosen. At the intake and out flow of this one-way airflow chamber are Tesla turbines which can rotate with airflow at near perfect efficiency when attaining certain rpm's.
Beneath this table-top is contained a fairly large bed of sand through which the expelled air, and wasted heat, causes the sand to fluidize and retain no small amount of the days heat.
The vented air and un-stored heat pass directly back into the initial Tesla turbines' intake retaining even more heat in the system.
Once in motion, the system should become fairly self sustaining as long as there remains a temperature differential.
I think. I wanted to bounce the concept off of you guys to see if I'm barking up the wrong tree.
(?) One version of this Idea
Solar_20Powered_20Wind_20Turbine
Bigger, though [Vernon, May 22 2016]
Solar updraft tower
https://en.wikipedi...Solar_updraft_tower
[AusCan531, May 22 2016]
Mildura Solar Tower concept.
https://structurae....mildura-solar-tower
[AusCan531, May 22 2016]
Tesla valve video .
https://www.youtube...watch?v=ozFBsMyyDSE
[2 fries shy of a happy meal, May 23 2016]
Tesla turbine
https://www.youtube...watch?v=mrnul6ixX90
[2 fries shy of a happy meal, May 23 2016]
How to make a Tesla turbine out of hard drive platters
http://www.instruct...-using-hard-drive-/
[notexactly, Jul 03 2016]
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This is so over my head, it ain't funny. |
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I think what is needed here is a diagram. And maybe
a little more explanation. For instance, is a Tesla
valve one of those fluid devices with recurved
channels that has more fluid resistance in one
direction than the other? |
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This isn't a bad idea functionally, just not so sure about
economically. A solar updraft tower 1km high [link] was
purportedly going to be built near Mildura, Australia. I
followed it with some interest until the promoters said "it
won't be economically viable without government
subisidies but will serve as a 'Demonstration Project.' "
I thought if one on that scale, in that climate. wasn't
capable of generating electricity at an economically
viable cost, then which solar tower would? They were
going to use molten salt as the heat reservoir for night-
time production. |
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The Tesla valves are a nice addition but if the slope of the
surrounding glass collector area feeds into the tower
cone already, surely the hot air is only going to go one
way anyway? |
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It's not over your head [bliss] check out the two videos and you'll get it. |
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I tried to do a sketch but it just got too messy. |
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It's about efficiency and the path of least resistance.
That video I can't find anymore powered an entire farm and used no heat sink other than that which the shade cloth kept the ground from losing. It worked as well at night as it did in the day and the micro-climate under the cloth is ideal for growing crops like ginseng, so it's win-win. |
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Enough farms producing more than their own power requirements and feeding it back to the grid makes far more sense to me than mile tall eye-sores. |
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I think that the Tesla valve conduits would allow for not needing a tower at all.
heated air would flow horizontally or even downwards which would be optimal for retaining the heat of the day, but it is the turbine that really piques my interest. |
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Build something the size of a card table or garage roof. |
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The Tesla turbine will shrink in size to match the flow available. |
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The the valve in the video seems a bit exotic. There must be a dozen simple flaps or valves or timers that can ensure one way flow. Or go without, because nothing will be damaged if it flows the wrong way for a bit. |
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A working model at an investors meeting would likely sell the project better than all the slides and video you might make. |
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Hire a local high school science class to make it as a class project. |
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Set the oven 345 F, put in this project in, and in six months you'll have something well baked. |
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I think this is super nifty! |
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if it floats on the water, Christo could make a copy, famousizing it, and it is also possible humid air is even better at rotating energy turbines |
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Yeah, the tesla turbine works with gas or fluid.
As I get time I'm going to try and make the table top version of this by routering the channel in plywood with a Plexiglas lid for the valve and compact disks for for the turbine fins, but I have to experiment and research a bit first.
How to make the turbine from scratch?
At what temperature do CD's warp?
Will I need glass rather than plexi?
Will it be more efficient to increase or decrease the individual channel volumes to meet expansion?
Can I wrap the valve itself around in a horse-shoe shape so that the intake and out-flow turn the same turbine?
Will it reach a stasis point temperature where there will be no air flow? |
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It should be fun. I'll post pictures. |
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hybridize it.. mount a traditional windmill on the tower as well? |
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would the temperature difference between the shaded & unshaded areas be of any use to a thermoelectric (TEG or Seebeck) generator? |
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//At what temperature do CD's warp?// |
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disc s are poly carbonate. |
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Since you will be cutting holes in the disc to let the spent air leave. And you will likely use a soldering iron to cut those holes, you will know about at what temps the discs will warp and melt. |
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"If such a disc is left in an environment that allows direct sunlight and extreme heat buildup (e.g., on the dashboard of a car in summertime, or next to a heater by a window), the organic dye or phase-changing film that holds the data will degrade quickly, causing the disc to become unreadable. A disc is not protected from the effects of heat buildup if left in a case that is exposed to direct sunlight or other sources of heat. Extreme heat buildup can also cause warping of the disc." from internet. |
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I just finished leaving one in full sun with the windows up for a week or so on the dash of my truck. I'm not worried about data just warp-age from flat. So far there has been none... at least on a visible level. |
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There will be no need to make holes in the CD's themselves, the only holes will be in the exhaust ports on either side of the curved turbine housing. |
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...on a side note, it's taking forever to transfer the Tesla valve pattern to the surface using carbon paper and a template then I thought.
Routering the pattern out will be only slightly less painstaking. |
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It's gonna take a few months at this rate.
just sayin |
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I think this needs a small change to make it work. Firstly, the solar updraft tower is not the best analogy, as gravity isn't driving the airflow. Think gas turbine instead. |
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So, what does drive the airflow? As described, nothing does. I think you will need to make the inlet turbine work as a compressor by driving it through a reduction gear from the outlet turbine. |
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hmm I think I see what you mean. The expanding air will need to escape and I think will cause a syphon effect at the intake, but the in-flow will be a lot less than the out-flow. |
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On a side note, the makers group in town here are building 3d printers from kits. I've got mine about half built now and want to first try printing interlocking 8 inch puzzle-piece Tesla valve segments so I can try this on a very small scale.
I think it might be possible to use the design in geodesic greenhouse panels so that heat can be moved passively downwards to vent inwards at ground level without fans or electricity. |
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Just to be clear, have you abandoned the vertical tower altogether? My comment was based on the assumption that you had. |
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//syphon effect// You're still not appreciating the gravity of the situation. It's certainly possible to use syphon effects to move air in useful ways on a small scale = some well-designed cellars and passive solar heating systems do. |
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But if you're talking about generating power, unless your vertical scale is very large, I think buoyancy can be safely ignored. |
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//the in-flow will be a lot less than the out-flow// A ballpark figure might be in-flow = 3/4 outflow. This is an interesting project, but don't expect it to compete with, say, photovoltaics for power generation. For good reason, solar thermal stations tend to be very big and/or very hot. |
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Yes, I have definitely abandoned the vertical tower on this one. I think it would be beneficial to make hot air flow downwards where it can be recouped. |
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As for power generation, the way I see it we can't keep doing the mega-projects to provide electricity. It's just not economically or environmentally efficient anymore.
We need to go cottage-industry where folks are encouraged to create more electricity than they use and can sell the excess back to the grid at wholesale cost to be resold at retail prices to businesses who don't make their own juice. |
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If a table-top version of this little widget can power a small electric motor, then that motor can turn two counter rotating flywheels to store that energy. If the flywheels begin to exceed optimum speed then energy can be bled to pump water to an elevated reservoir where the energy is stored in a different manner.
A garden shed version should power a small farm.
An industrial greenhouse version should make substantial power. |
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With the small greenhouse application I just want to make passive airflow.
By use of bees-wax rams any extra heat can be made to exit the greenhouse and be stored to be released at night and perhaps by combining rammed-earth, geothermal, compost, animal heat and cold-sink designs in one structure it may be possible to create a semi-arctic growing environment that is self sufficient even while entirely off the grid. |
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I want the system to create so much excess heat that my home furnace never needs to kick on in winter and I turn the rest into a small cheque instead of a large bill every month from the power company during the summer. |
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Lately I've been toying with ways for a structure to passively condense its own water supply from the atmosphere. |
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My wife and I are looking to sell our place here in the city and look for acreage soon and I'm itching to try out some of this stuff.
Between permaculture, power generation and Treethedral I'm gonna start a little Eden before I die.
<knocks on wood> |
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I'm guessing you're somewhere around Kelowna. I'm not sure how many clear nights you have there compared to Vancouver (not many here), but I recall quite a few from my time in Summerland. I bring this up because I have an idea related to yours which I don't want to submit for scrutiny here since it's not really inventive, but may be of interest to you, or at least as an augmentation to your idea. |
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Use solar-thermal vacuum tubes on your land, or land you have access to, to heat an insulated reservoir of oil, and simultaneously power either/both nitinol engines/beta-type Stirling engines. The efficiency of the Stirling in particular is directly proportional to the heat differential across it (Carnot), and the nitinol engine is well suited to using the waste heat from the Stirling cycle. |
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Night would be where the interesting part comes in. The parabolic troughs containing the vacuum tubes could contain a second antifreeze-filled pipe that can be brought into focus after dark, designed to dump heat. As this fluid picks up heat from the Stirling, it would first be run through a air-cooled heat-exchanger to dump heat to the atmosphere. After that the fluid would continue to the parabolic troughs where it would radiate heat to deep space. Depending on conditions, the fluid may drop in temperature below ambient. |
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This generates the biggest heat differential possible between the stored hot oil and deep space thus the greatest efficiency of the Stirling. It can be scaled to however big you like. |
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