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Terrain Enabled Wind Power (TEWP)

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  • dave santos
    Hills & mountains present localized opportunities for high density wind power. Cables strung in midair between these natural towers are cheap simple reliable
    Message 1 of 15 , Oct 5, 2009
      Hills & mountains present localized opportunities for high density wind power. Cables strung in midair between these natural towers are cheap simple reliable means to place wind power elements in good wind. This is Terrain Enabled Wind Power (TEWP)
       
      The Technology
       
      Mountains of about 12,000 ft are quite common & cable runs of several kilometers are easily applied. Membrane wing-mills of up to about 1000 x 100 ft are manageable 10mw class elements to hang from terrain. Aggregation to gigawatt scale would be feasible at good sites.
       
      Initial runs of cable could be heddle-pulleyed to amplify amplitude & speed of power pulses. Multiple wing arrays would fan-in & aggregate power in stages as the cables run downward. Multi-spragged shafts accept asynchronous kicks from wing-mills that by stages are "refined" into smooth aggregated power. Moving cable loops will run quite nicely down to populations far below the mountain tops.
       
      Every category of wind power element can hang from terrain- turbines, wing-mills, & varidrogues of every description could find niches. Even simple hollows in the ground look valuable to leave hanging kite elements in calm that reliably relaunch to higher altitude when wind returns. Generators can be hung midair from terrain much more safely than flying on a tether. Hardware suspended from terrain considerably relaxes engineering weight allowances. Furling & hotswapping will be parctical.
       
      Anchoring to mountains could ideally resemble from low impact rock climbing, scaled up, where an array of wedges & specialty anchors borrow existing features. Suspension bridge practice has models for anchoring in poor media. Areial tramway & cableway tech provides a vast pool of soultions for TEWP.
       
      Cables strung on terrain are far more reliable than kites or UAVs. While the best sites are rare, nobody is using them yet. A handful of mountain sites even reach the lower stratosphere. TEWP will be an outstanding opportunity to refine high altitude AWE tech.
       
      The Resource
       
      Mountains have diverse wind mechanisms. Gap winds are amplified flow across mountain ridges set across a prevailing wind. Valley winds have a nice feature of being fairly straight & clean in the center of the jet. Ridges that run parallel to prevailing wind still allow numerous cables to be strung across the flow. Mountains can create gap & valley winds driven merely by daily heating & cooling. Sea breezes can drive nice amplified gap winds at low altitudes.
       
      North & South America's "Sierra Madres" taken together represent the biggest TEWP gap wind resource as these mountain ranges stretch across prevailing global wind. Many other ranges, like the Urals, Appalacia, Japanese Alps, & Norway's coast range are well situated. Certain gaps are ideal, like the Columbia River Gorge.
       
      Modifying wind has environmental consequences. Slower kite-like elements are far more bird friendly than high speed turbines. At a distance TEWP cables are invisible & the wing elements can be camouflaged to match sky of terrain. Light grey will particularly disappear against a sky. A cautious TEWP approach would only block about 20% of a local flow & monitor for ecological damage. In some places increased wind caused by climate change might even be mitigated.
       
      [This is a KiteLab Group cooperative IP disclosure]
       

    • Bob Stuart
      We should probably look for favorable geography that already has a power transmission line handy as a market entry point. Remote communities might also be
      Message 2 of 15 , Oct 5, 2009
        We should probably look for favorable geography that already has a power transmission line handy as a market entry point.

        Remote communities might also be pioneers for these installations.  AWE installations save on transportation costs, and can make a financial success even with a prototype that mules out, as long as it can still compete with imported diesel.

        Bob Stuart




        On 5-Oct-09, at 3:38 PM, dave santos wrote:

         

        Hills & mountains present localized opportunities for high density wind power. Cables strung in midair between these natural towers are cheap simple reliable means to place wind power elements in good wind. This is Terrain Enabled Wind Power (TEWP)

      • harry valentine
        There are many parts of the world where terrain enabled wind power has definate possibilities. Powerful winds blow off the Northeastern Atlantic and right up
        Message 3 of 15 , Oct 5, 2009
          There are many parts of the world where terrain enabled wind power has definate possibilities. Powerful winds blow off the Northeastern Atlantic and right up the fiords of Norway and off the Northeastern Pacific up the inlets of British Columbia. A similar situation exists in Southern Chile and parts of Peru, as well as in the mountains of Central America.
           
           
          There is also a boundary layer effect that can steer winds around many gently curved entrances to many mountain valleys and the winds then directed by the "channel effect". The effect is similar to the boundary layer effect that occurs on the top surface of airplane wings.
           
           
          The lateral-axis turbine from BroadStar of Texas can be coupled using flexible drive-joints when cable-suspended across valleys, to allow multiple turbines to drive wach electrical alternators. Such a layout can reduce overall capital cost per kilowatt.
           
           
          Unfortunately, governments have directed funding into developing tower based wind turbines and next to nothing on airborne and towerless wind technologies.
           
           
          Harry
           

          To: airbornewindenergy@yahoogroups.com
          From: santos137@...
          Date: Mon, 5 Oct 2009 14:38:12 -0700
          Subject: [AirborneWindEnergy] Terrain Enabled Wind Power (TEWP)

           
          Hills & mountains present localized opportunities for high density wind power. Cables strung in midair between these natural towers are cheap simple reliable means to place wind power elements in good wind. This is Terrain Enabled Wind Power (TEWP)
           
          The Technology
           
          Mountains of about 12,000 ft are quite common & cable runs of several kilometers are easily applied. Membrane wing-mills of up to about 1000 x 100 ft are manageable 10mw class elements to hang from terrain. Aggregation to gigawatt scale would be feasible at good sites.
           
          Initial runs of cable could be heddle-pulleyed to amplify amplitude & speed of power pulses. Multiple wing arrays would fan-in & aggregate power in stages as the cables run downward. Multi-spragged shafts accept asynchronous kicks from wing-mills that by stages are "refined" into smooth aggregated power. Moving cable loops will run quite nicely down to populations far below the mountain tops.
           
          Every category of wind power element can hang from terrain- turbines, wing-mills, & varidrogues of every description could find niches. Even simple hollows in the ground look valuable to leave hanging kite elements in calm that reliably relaunch to higher altitude when wind returns. Generators can be hung midair from terrain much more safely than flying on a tether. Hardware suspended from terrain considerably relaxes engineering weight allowances. Furling & hotswapping will be parctical.
           
          Anchoring to mountains could ideally resemble from low impact rock climbing, scaled up, where an array of wedges & specialty anchors borrow existing features. Suspension bridge practice has models for anchoring in poor media. Areial tramway & cableway tech provides a vast pool of soultions for TEWP.
           
          Cables strung on terrain are far more reliable than kites or UAVs. While the best sites are rare, nobody is using them yet. A handful of mountain sites even reach the lower stratosphere. TEWP will be an outstanding opportunity to refine high altitude AWE tech.
           
          The Resource
           
          Mountains have diverse wind mechanisms. Gap winds are amplified flow across mountain ridges set across a prevailing wind. Valley winds have a nice feature of being fairly straight & clean in the center of the jet. Ridges that run parallel to prevailing wind still allow numerous cables to be strung across the flow. Mountains can create gap & valley winds driven merely by daily heating & cooling. Sea breezes can drive nice amplified gap winds at low altitudes.
           
          North & South America's "Sierra Madres" taken together represent the biggest TEWP gap wind resource as these mountain ranges stretch across prevailing global wind. Many other ranges, like the Urals, Appalacia, Japanese Alps, & Norway's coast range are well situated. Certain gaps are ideal, like the Columbia River Gorge.
           
          Modifying wind has environmental consequences. Slower kite-like elements are far more bird friendly than high speed turbines. At a distance TEWP cables are invisible & the wing elements can be camouflaged to match sky of terrain. Light grey will particularly disappear against a sky. A cautious TEWP approach would only block about 20% of a local flow & monitor for ecological damage. In some places increased wind caused by climate change might even be mitigated.
           
          [This is a KiteLab Group cooperative IP disclosure]
           




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        • Joe Faust
          * TEWP Terrain Enhanced Wind Power * Spiders are leaders on this realm; they form webs from terrain and terrain-based structures. Insects by flight and wind
          Message 4 of 15 , Oct 6, 2009
              TEWP  Terrain Enhanced Wind Power 
            • Spiders are leaders on this realm; they form webs from terrain and terrain-based structures. Insects  by flight and wind become little kites as they get caught in webs. The motion is part of the game of energy exchange; motion warns the spider; the kited insect caught becomes food converted to energy for the spider.  
            • Pierre Benhaïem has forwarded many TEWP concepts.
            • Harry Valentine  has supplied many drawings re: TEWP
            • M344 begins a thread of discussion on TEWP
            • Count buildings as terrain. Dams, skyscrapers. decommissioned hard-towers of ground-hugging wind power turbines.
          • John O
            The prominence of Skyscrapers in Urban Centres and Business Districts often built within close proximity of one another provides a good opportunity for TEWP
            Message 5 of 15 , Oct 7, 2009
              The prominence of Skyscrapers in Urban Centres and Business Districts often built within close proximity of one another provides a good opportunity for TEWP and AWE especially if EU-TEWP could be deployed for powering lifts in these building amongst other uses that might include pumping water from on-site bore-holes.

              --- In AirborneWindEnergy@yahoogroups.com, dave santos <santos137@...> wrote:
              >
              >
              >
              >
              >
              > Hills & mountains present localized opportunities for high density wind power. Cables strung in midair between these natural towers are cheap simple reliable means to place wind power elements in good wind. This is Terrain Enabled Wind Power (TEWP)
              >  
              > The Technology
              >  
              > Mountains of about 12,000 ft are quite common & cable runs of several kilometers are easily applied. Membrane wing-mills of up to about 1000 x 100 ft are manageable 10mw class elements to hang from terrain. Aggregation to gigawatt scale would be feasible at good sites.
              >  
              > Initial runs of cable could be heddle-pulleyed to amplify amplitude & speed of power pulses. Multiple wing arrays would fan-in & aggregate power in stages as the cables run downward. Multi-spragged shafts accept asynchronous kicks from wing-mills that by stages are "refined" into smooth aggregated power. Moving cable loops will run quite nicely down to populations far below the mountain tops.
              >  
              > Every category of wind power element can hang from terrain- turbines, wing-mills, & varidrogues of every description could find niches. Even simple hollows in the ground look valuable to leave hanging kite elements in calm that reliably relaunch to higher altitude when wind returns. Generators can be hung midair from terrain much more safely than flying on a tether. Hardware suspended from terrain considerably relaxes engineering weight allowances. Furling & hotswapping will be parctical.
              >  
              >
              > Anchoring to mountains could ideally resemble from low impact rock climbing, scaled up, where an array of wedges & specialty anchors borrow existing features. Suspension bridge practice has models for anchoring in poor media. Areial tramway & cableway tech provides a vast pool of soultions for TEWP.
              >  
              > Cables strung on terrain are far more reliable than kites or UAVs. While the best sites are rare, nobody is using them yet. A handful of mountain sites even reach the lower stratosphere. TEWP will be an outstanding opportunity to refine high altitude AWE tech.
              >  
              > The Resource
              >  
              > Mountains have diverse wind mechanisms. Gap winds are amplified flow across mountain ridges set across a prevailing wind. Valley winds have a nice feature of being fairly straight & clean in the center of the jet. Ridges that run parallel to prevailing wind still allow numerous cables to be strung across the flow. Mountains can create gap & valley winds driven merely by daily heating & cooling. Sea breezes can drive nice amplified gap winds at low altitudes.
              >  
              > North & South America's "Sierra Madres" taken together represent the biggest TEWP gap wind resource as these mountain ranges stretch across prevailing global wind. Many other ranges, like the Urals, Appalacia, Japanese Alps, & Norway's coast range are well situated. Certain gaps are ideal, like the Columbia River Gorge.
              >  
              > Modifying wind has environmental consequences. Slower kite-like elements are far more bird friendly than high speed turbines. At a distance TEWP cables are invisible & the wing elements can be camouflaged to match sky of terrain. Light grey will particularly disappear against a sky. A cautious TEWP approach would only block about 20% of a local flow & monitor for ecological damage. In some places increased wind caused by climate change might even be mitigated.
              >  
              > [This is a KiteLab Group cooperative IP disclosure]
              >  
              >
            • benhaiemp
              With thanks to Joe for welcome. Turbine of type Darrieus between mounts or buildings Simulation on an animation
              Message 6 of 15 , Oct 7, 2009

                With thanks to Joe for welcome.

                Turbine of type Darrieus between mounts or buildings 

                Simulation on an animation between EDF (Electricité de France) building and another building 

                Application for a French patent  FR2927671  (A1).

                There are horizontal axis turbines of type Darrieus,and (concepts of) devices between mounts,but not yet horizontal axis turbines of type Darrieus between mounts or buildings.

                Advantages:higher area swept (not only between but also in altitude),simplicity,easy anchoring.However Darrieus turbines are known for risonance problems.Maybe theese problems can be avoid with new materials as "tensairity" which lightness also would make easier the fabrication of great blades.

                 

                 

              • Darin Selby
                Maybe that s what a tear in the fabric of space time would look like, too. To: AirborneWindEnergy@yahoogroups.com From: pierre.benhaiem@orange.fr Date: Wed, 7
                Message 7 of 15 , Oct 7, 2009
                  Maybe that's what a tear in the fabric of space time would look like, too.


                  To: AirborneWindEnergy@yahoogroups.com
                  From: pierre.benhaiem@...
                  Date: Wed, 7 Oct 2009 20:53:31 +0000
                  Subject: [AirborneWindEnergy] Terrain Enabled Wind Power (TEWP)

                   

                  With thanks to Joe for welcome.
                  Turbine of type Darrieus between mounts or buildings 
                  Simulation on an animation between EDF (Electricité de France) building and another building 
                  Application for a French patent  FR2927671  (A1).
                  There are horizontal axis turbines of type Darrieus,and (concepts of) devices between mounts,but not yet horizontal axis turbines of type Darrieus between mounts or buildings.
                  Advantages:higher area swept (not only between but also in altitude),simplicit y,easy anchoring.However Darrieus turbines are known for risonance problems.Maybe theese problems can be avoid with new materials as "tensairity" which lightness also would make easier the fabrication of great blades.
                   
                   



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                • benhaiemp
                  Message 8 of 15 , Oct 7, 2009
                    --- In AirborneWindEnergy@yahoogroups.com, Darin Selby <darin_selby@...> wrote:
                    >
                    >
                    > Maybe that's what a tear in the fabric of space time would look like, too.
                    >
                    > To: AirborneWindEnergy@yahoogroups.com
                    > From: pierre.benhaiem@...
                    > Date: Wed, 7 Oct 2009 20:53:31 +0000
                    > Subject: [AirborneWindEnergy] Terrain Enabled Wind Power (TEWP)
                    >
                    >
                    > Explain
                    >
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                    > With thanks to Joe for welcome.
                    >
                    > Turbine of type Darrieus between mounts or buildings
                    >
                    > Simulation on an animation between EDF (Electricité de France) building and another building
                    >
                    > Application for a French patent FR2927671 (A1).
                    >
                    > There are horizontal axis turbines of type Darrieus,and (concepts of) devices between mounts,but not yet horizontal axis turbines of type Darrieus between mounts or buildings.
                    >
                    > Advantages:higher area swept (not only between but also in altitude),simplicity,easy anchoring.However Darrieus turbines are known for risonance problems.Maybe theese problems can be avoid with new materials as "tensairity" which lightness also would make easier the fabrication of great blades.
                    >
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                    > _________________________________________________________________
                    > Your E-mail and More On-the-Go. Get Windows Live Hotmail Free.
                    > http://clk.atdmt.com/GBL/go/171222985/direct/01/
                    >
                  • Darin Selby
                    It looks like this is what would happen if one were to fly through the center of it when it appears as if it opens :
                    Message 9 of 15 , Oct 7, 2009
                      It looks like this is what would happen if one were to fly through the center of it when it appears as if it "opens": http://www.youtube.com/watch?v=Q6Rw2i2iXYs

                      Seriously, how is something that would span such a great distance be able to keep its intended shape?  Especially with any kind of torque from spinning a generator at one or both the ends?  

                      The torque issue can be cancelled by many contra-rotating pairs of propeller blades, with small generators in-between each pair.  Have them placed at intervals on a tension wire that's stretched across the same span.   







                      To: AirborneWindEnergy@yahoogroups.com
                      From: pierre.benhaiem@...
                      Date: Thu, 8 Oct 2009 03:11:15 +0000
                      Subject: [AirborneWindEnergy] Re: Terrain Enabled Wind Power (TEWP)

                       


                      --- In AirborneWindEnergy@ yahoogroups. com, Darin Selby <darin_selby@ ...> wrote:
                      >
                      >
                      > Maybe that's what a tear in the fabric of space time would look like, too.
                      >
                      > To: AirborneWindEnergy@ yahoogroups. com
                      > From: pierre.benhaiem@ ...
                      > Date: Wed, 7 Oct 2009 20:53:31 +0000
                      > Subject: [AirborneWindEnergy ] Terrain Enabled Wind Power (TEWP)
                      >
                      >
                      > Explain
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      >
                      > With thanks to Joe for welcome.
                      >
                      > Turbine of type Darrieus between mounts or buildings
                      >
                      > Simulation on an animation between EDF (Electricité de France) building and another building
                      >
                      > Application for a French patent FR2927671 (A1).
                      >
                      > There are horizontal axis turbines of type Darrieus,and (concepts of) devices between mounts,but not yet horizontal axis turbines of type Darrieus between mounts or buildings.
                      >
                      > Advantages:higher area swept (not only between but also in altitude),simplicit y,easy anchoring.However Darrieus turbines are known for risonance problems.Maybe theese problems can be avoid with new materials as "tensairity" which lightness also would make easier the fabrication of great blades.
                      >
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                      > ____________ _________ _________ _________ _________ _________ _
                      > Your E-mail and More On-the-Go. Get Windows Live Hotmail Free.
                      > http://clk.atdmt. com/GBL/go/ 171222985/ direct/01/
                      >




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                    • benhaiemp
                      With new light structures as Tensairity elements for beams and kites light rigid 50 m span
                      Message 10 of 15 , Oct 8, 2009
                        With new light structures as "Tensairity" elements for beams and kites light rigid 50 m span kites are studied.So it would be possible to conceive an enough rigid gigantic Darrieus rotor with beams and blades with theese elements.

                        The device you describe has a limitated area swept to the high of the small turbines.Generators and blades are on the too sollicited wire.

                        For the video:out of subject.

                         

                        Darin Selby wrote:

                        It looks like this is what would happen if one were to fly through the center of it when it appears as if it "opens": http://www.youtube.com/watch?v=Q6Rw2i2iXYs


                        Seriously, how is something that would span such a great distance be able to keep its intended shape?  Especially with any kind of torque from spinning a generator at one or both the ends?  

                        The torque issue can be cancelled by many contra-rotating pairs of propeller blades, with small generators in-between each pair.  Have them placed at intervals on a tension wire that's stretched across the same span.
                      • Darin Selby
                        I guess that by sending that email four times, means that you must be really serious with being right about your design. That s okay, in fact, that s really
                        Message 11 of 15 , Oct 8, 2009
                          I guess that by sending that email four times, means that you must be really serious with being right about your design.  That's okay, in fact, that's really okay, because you have just given to me an incredible, much different idea from your own.  And why would I want to share this new concept with someone who has no sense of humor?


                          To: AirborneWindEnergy@yahoogroups.com
                          From: pierre.benhaiem@...
                          Date: Thu, 8 Oct 2009 11:58:12 +0000
                          Subject: [AirborneWindEnergy] Terrain Enabled Wind Power (TEWP)

                           

                          With new light structures as "Tensairity" elements for beams and kites light rigid 50 m span kites are studied.So it would be possible to conceive an enough rigid gigantic Darrieus rotor with beams and blades with theese elements.
                          The device you describe has a limitated area swept to the high of the small turbines.Generators and blades are on the too sollicited wire.
                          For the video:out of subject.
                           
                          Darin Selby wrote:
                          It looks like this is what would happen if one were to fly through the center of it when it appears as if it "opens": http://www.youtube. com/watch? v=Q6Rw2i2iXYs

                          Seriously, how is something that would span such a great distance be able to keep its intended shape?  Especially with any kind of torque from spinning a generator at one or both the ends?  

                          The torque issue can be cancelled by many contra-rotating pairs of propeller blades, with small generators in-between each pair.  Have them placed at intervals on a tension wire that's stretched across the same span.



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                        • dave santos
                          Pierre had an email glitch & the best way to deal with off-topic issues like that is off-list.   Darius & savonius turbines are cursed by return-side drag.
                          Message 12 of 15 , Oct 8, 2009
                            Pierre had an email glitch & the best way to deal with off-topic issues like that is off-list.
                             
                            Darius & savonius turbines are cursed by return-side drag. Their aero surfaces are poor performers by either bad form or  trim. They are high-mass high capital-cost pigs. Their visual appeal keeps them alive many decades after performance oriented aerodynamicists dropped them.
                             
                            What i first saw in Pierre's cool impressions was a membrane wing mill, which is far less scale limited & performs with a more birdlike efficiency, especially by mass, than a bad turbine. Picture a bird-like "gallloping" wing form suspended across a gap rather than a wind-belt flutter-tape.
                             
                            Pierre's earlier AWE scheme with the trains of sweeping kites would work well suspended across terrain in a prevailing wind, preventing snarls.
                             


                            --- On Thu, 10/8/09, Darin Selby <darin_selby@...> wrote:

                            From: Darin Selby <darin_selby@...>
                            Subject: RE: [AirborneWindEnergy] Terrain Enabled Wind Power (TEWP)
                            To: airbornewindenergy@yahoogroups.com
                            Date: Thursday, October 8, 2009, 10:00 AM

                             
                            I guess that by sending that email four times, means that you must be really serious with being right about your design.  That's okay, in fact, that's really okay, because you have just given to me an incredible, much different idea from your own.  And why would I want to share this new concept with someone who has no sense of humor?


                            To: AirborneWindEnergy@ yahoogroups. com
                            From: pierre.benhaiem@ orange.fr
                            Date: Thu, 8 Oct 2009 11:58:12 +0000
                            Subject: [AirborneWindEnergy ] Terrain Enabled Wind Power (TEWP)

                             

                            With new light structures as "Tensairity" elements for beams and kites light rigid 50 m span kites are studied.So it would be possible to conceive an enough rigid gigantic Darrieus rotor with beams and blades with theese elements.
                            The device you describe has a limitated area swept to the high of the small turbines.Generators and blades are on the too sollicited wire.
                            For the video:out of subject.
                             
                            Darin Selby wrote:
                            It looks like this is what would happen if one were to fly through the center of it when it appears as if it "opens": http://www.youtube. com/watch? v=Q6Rw2i2iXYs

                            Seriously, how is something that would span such a great distance be able to keep its intended shape?  Especially with any kind of torque from spinning a generator at one or both the ends?  

                            The torque issue can be cancelled by many contra-rotating pairs of propeller blades, with small generators in-between each pair.  Have them placed at intervals on a tension wire that's stretched across the same span.



                            Hotmail: Free, trusted and rich email service. Get it now.

                          • Joe Faust
                            Pierre, DaveS, DarinS, HarryV, have started to expose a wide variety of TEWP AWECS. DaveS suggested that just about any known AWECS form may have a niche place
                            Message 13 of 15 , Oct 8, 2009

                              Pierre, DaveS, DarinS, HarryV, have started to expose a wide variety of TEWP AWECS. DaveS suggested that just about any known AWECS form may have a niche place in terrain-using AWECS. The first emphasis by Pierre on Darrieus sets a scene for other considerations.  Mounting a cable, hang from a cable, using the cable as a working element, etc. seems to provide a rich space for design.   Recall HarryV's drawings:

                              http://www.energykitesystems.net/HarryValentine/BoundaryLayerValleyEntrance.jpg
                              http://www.energykitesystems.net/HarryValentine/Valley-Sails-Desert.pdf
                              http://www.energykitesystems.net/HarryValentine/Valley_Boundary_layer.pdf

                              Reaching for an element, I bring a quick sketch of a scheme that could pump water to a high lake; drop the lake water through a hydro turbine.

                               
                            • benhaiemp
                              Precisions for messages: I post a precedent message 4 times and delete 3 times for different reasons:transcription difficulties,mistakes on contra-rotating
                              Message 14 of 15 , Oct 8, 2009

                                Precisions for messages:

                                I post a precedent message 4 times and delete 3 times for different reasons:transcription difficulties,mistakes on contra-rotating blades,and on "Tensairity" name (not "Tensiraity").

                                It is interesting for me to correspond with Dave,Darin,Harry.AWE and TEWP are good subjects because of the mix of simplicity and extrem complexity.

                                On turbine outputs,classical turbines are about 60% Betz limit,Darrieus 40%,Savonius 20%.Darrieus and classical turbines work with lift,Savonius with differential drag.Solidity coefficient of Savonius turbine is about 1 (area swept = surface of blades):so great rotors are not possible.Solidity coefficient of  classical turbines are about 0,1 and lesser for Darrieus turbines.

                                Problems of Darrieus turbine are (with described problems by Harry,except for solidity coefficient):great peripheric masses,risonances,but not really output (lesser but not so bad,see Cap-Chat,4 MW Darrieus turbine).Maybe it would be possible to produce a good shape with Tensairity elements if solid parts cross the wind;and also maybe with high pressure inflatable blades.

                                New firms as Ropatec  produce turbines of type Darrieus ("H "version) with a good output,and new light matters could change some characteristic on Darrieus turbine.

                                Classical propeller blades are better than Darrieus turbines but their position between mounts or buildings are less natural,and their area swept capacities are lower for this context.The shape of Darrieus blades can follow the relief.

                                OrthoKiteBunch works according to all wind directions with the swivelling tray.

                              • Darin Selby
                                After seeing the single Darrieus rotor design that would span between two peaks, or buildings, I was giving it some more thought. It would appear that many
                                Message 15 of 15 , Oct 8, 2009
                                  After seeing the single Darrieus rotor design that would span between two peaks, or buildings, I was giving it some more thought.  It would appear that many contra-rotating Darrieus rotors, across the same cable tension line, would be a more reliable system.  In other words, one rotor spins one way, the next one spins the other way, etc.  

                                  In-between each rotor is a generator system.  The housing(s) of a generator system is attached to the end of one Darrieus rotor, the armature is attached to the next.  How this would be accomplished?  The main thing is to design the blades, and the generators, so that they can be easily removed, and replaced from around the tension cable.  

                                  This could mean having three generators, that are equilaterally-balanced around the end of a spinning Darrieus rotor.  Three friction gears, one from each generator, roll over a"tube" surface, that is centered on the cable with bearings.  That tube spins the other direction; since it is connected to the next-in-line "contra"-spinning rotor.  So then, it'sdouble-time, for the spinning of each generator!

                                  With the presently-designed system mentioned in the forum, eventually the maintenance of the two HUGE blades will have to be dealt with.  As well, there will be much torsion applied upon them in high winds.  Having large generators at each end, with their resistance torque factors, will greatly contribute to the stressing along the long span of these two blades.

                                  This design that I am presenting, uses much smaller, more manageable Darrieus rotor units, that are placed side-by-side, like on a string of beads, and all are contra-spinning on this tension cable.  Being stretched across a vast span of area, it will make the entire system much more durable, easier to work on, and easier to replace any defective part.  

                                  The generators can also be switched over to be motors, to kick-start the Darrieus rotors into spinning at their optimal rotation.   

                                  How to accomplish any repairs?  Well, I would prefer using an airship over a helicopter, for the job of lowering a person(s) down to replace a defective unit.  Perhaps a blimp could actually be set aside, and ready in a hangar, just for this purpose?  

                                  I have recently found information on how to safely make the use of hydrogen as the lifting gas in a blimp. US 20040155149  Basically, it is a balloon-in-a-balloon.  The inner envelope is filled with hydrogen.  The outer, slightly-larger envelope is filled with a "blanket" ofnitrogen.  

                                  Why go to all this trouble?  Why not just use non-flammable helium as the lifting gas?  Because helium is a non-renewable government-controlled gas.  It takes about $1000 of it to lift 300 pounds, with a 20 ft. diameter balloon.  

                                  Doing it this new way protects the H2 from contacting the O2.  And the entire process is then decentralized.  Pressure swing adsorption (PSA) of compressed air through a zeolite sieve, will make the nitrogen gas.  http://en.wikipedia.org/wiki/Pressure_swing_adsorption 

                                  The very energy substance that this string of Darrieus rotors could produce, could be hydrogen gas.  It would then be not only the gas to run the fuel cells, which run a compressor to make the nitrogen, etc., but also the lifting gas for doing any repairs by utilizing a blimp!

                                  Here is a short rhyming story that I've written around this balloon-in-a-balloon airship concept.  And, this one spins like a football being thrown through the air!  This will make the overall size of the envelope needed to be much smaller, to lift the same amount of weight:  http://darinselby.1hwy.com/spinningairshipglider03.html



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