Doug,   That ARPA-E turns out not to be as militaristic as ARPA/DARPA is a fine (partial) correction, exactly as repeatedly requested. The many other points presented to document the AWE militarization pattern still stand & the list grows. Nobody on this forum thinks they can by themselves stop militarism, that is a false charge. One can try against odds & hope others join.   As for evidence of "delusional self-glorification" & "imagining ones self as...genius & savior for solving the energy crisis", that is an upcoming topic (Narcissism Pattern in Early AWE).   Here is a selected preview-

Hi I just saw these guys
"Altaeros"
mentioned on TV as a denizen of a tech incubator center in Boston.
A helium-Inflated duct/shroud flying turbine.
More kids with renderings & the powerpoint mentality:
Tell a compelling story, get funded, waste the money for no results, move on with no product but with now some extra change in your pocket, complaining about "global warming" etc.
Physically this could work.
Economically may be another story.
Should be easy to build a 1 kW example.
Let's see one.
Oh wait...
Let me guess...
"It is only at the megawatt scale that we envision the scaling parameters will bring our technology into the sweet spot of efficacy blah blah blah blah"
and all the words will be meaningless
just skip to the end where they'll ask for millions of future wasted dollars because, somehow, their superior design can't be built at a smaller scale.
It would be interesting if something came about that would force people to prove their statements at some consequence for not coming through on what they say. I am so tirwed of rreading lie after lie in the form of press releases while true solutions sit unrecognized and undeveloped.
Doug Selsam

Rob Creighton of Windlift in North Carolina must be admired for staying out of all these arguments while quietly producing power from what looks like a pretty well developed ground-gen rig.

www.youtube.com/watch?v=l4HSYaWXLYM

Way to go Rob.

- Dimitri

Attachments :

communications_techniques.pdf

Attachments :

Helium is currently very cheap, but in 25 years, it will be almost priceless.

Latest predictions declare helium to be mostly exhausted as a resource in about 30 yrs, if today's consumption rate holds. Its a rare fossil element found only in few places & often wasted. Prices will rise relentlessly. Helium based AWE faces a marginal future.   Issac Asimov was the first helium conservation activist decades ago. No more helium will be sad.

dave santos schrieb:
Well, a lot of more important resources will be dwindling long before that. For
lifting purposes especially of unmanned devices hydrogen can be used. Hydrogen
is less dangerous than most people think. It is however important to avoid
getting oxygen or air into the hydrogen space in order to avoid getting an
explosive mixture. The loss of hydrogen can be offset by producing this onboard
using tiny electrolysers.

Keith Stewart did use helium instead of hydrogen in his kites, but then he
smoked at the time.

Theo Schmidt

Wow where did you dig that one up?
Do you think it is not true?
I've never had any luck contacting Pickens.
His hot-air group used to send me e-mails almost daily.
Couldn't seem to get one back thru to T-Bone Hiccups.
He bought something like 1000 G.E. turbines, the relaized he didn't have a power-purchase agreement and had to sell them off, from what I've heard. Typical newbie mistake.
Many people have declared if only Pickens and I could team up we could "solve the problem".
More than one has declared in no uncertain terms that they would introduce Pickens and me.
None have.
I am beginnning to doubt if there is really any energy crisis at all.
Look at all those methane hydrates. Look at all that oil.
It seems that most everything you read these days is a lie.
The latest lies today:
1) CNBC coverage of New Orleans after Katrina: 25% lower population - all the poor people moved out. Few homes rebuilt. Things about the same except for less population. Most of that hurricane recovery money wasted. As usual the bureaucracy stood in its own way.
2) Speaking of hurricanes in the gulf, our top weather "scientists" declared a few years back that they knew with scientific certainty that we'd have a few years of horrendous hurricane seasons, due to global warming, since the oceans were warm. Al Gore concurred, with great fanfare and a nobel prize. Result: 3 of the mildest hurricane seasons in recorded history.
All in all, most of what you read is lies.
So if yo have any more, might as well tell them now.
Hint: if you say you are developing a high altitude wind energy system and then you don't, that will turn out to be a lie. That includes individuals and highly-funded groups. We're drowning in lies.
Doug Selsam

Sometime in the last year I had mentioned something about my work with the Finite Element Modeling company and someone replied about their work in Fluid Dynamics. Does anyone remember who that was and are they still on this list? If so, contact me.
-brooks

________________________________________
PeoplePC Online
A better way to Internet
http://www.peoplepc.com

Liquid helium is precious to cryogenics, particularly for SQUIDs, not just in pure science, but particularly MRI medical imaging. Also Helium is quite inert while Hydrogen is very reactive & corrodes many structural materials. Helium provides a safety factor in many apps like LTA. People will die when forced to choose Hydrogen as a substitute. Helium is only about 90% as bouyant as Hydrogen in air, but it leaks slower & holds pressure better. One could go on about the special virtues of Helium, but AWE does not need it (except perhaps for a tiny pilot-balloon to get a pilot-kite above surface calm & initiate a massive launch sequence).   ================================   The main problem with reel-out is that it complicates the AWECS state-machine with an unnecessary overlaid meta-cycle, negatively impacting many design/control parameters. A sweep cycle that hums along without interruption is far better. The rowing-machine/lever cycle matched to a figure-of-eight sweep cycle, as indentified by WPI & optimised by KiteLab, shows how to avoid the reel-out method.   Another problem is the long-period negative-capacity-factor gap during reel-in, which necessitates more storage to buffer the power-out. Extra line wear by constant reeling & poorer land/airspace utilization are also issues.   True cross-wind sailing is faster than any point of sail downwind. The best reel-out with a sweeping kite most slowly gives ground downwind, better still to not give ground at all.   The necessary trade-off for no reel-out is that a higher mechanical-advantage first stage is needed to properly tap the power-sweep sine-wave, like a strong lever. Having tested both, it seems a worthwhile trade.

In fact reel-out systems are not so different from lever systems about a point:on a reel-out system tether is perpendicular in the axis of drum,so the transmission is optimal.For an optimal transmission with a lever system,the tether must be perpendicular in the lever.So there is a downwind component of the same value with both reel-out and lever systems.In the same way the train configuration of Kitegen carousel would be similar in reel-out system while the lever configuration (of Kitegen carousel) would be similar in...lever system,and there is also a downwind component.According to some papers optimal downwind component is 1/3 wind speed.Thank to correct it if it is wrong. 

PierreB

DaveS,and also DaveL for possible corrections of this message,and all,

What I want to say:all groundgens have a downwind component:with reel-out system materialization of this component is unwinding;translation for lever system is both the angular move of lever and its length.Optimal length of unwound tether should be the same value than optimal length of lever.
If tether anchor is not mobile (no unwinding or length of lever = 0),the kite not produces torque,downwind component = 0,power = 0.
Between 0 and optimal length there are values according to objectives.

It is true that modelisation of the two phases of reel-out system is more complex,but it is also true that said system has less mechanical constraints,and lets to keep a tangential force on the drum about is the position of the kite on a vertical plan.Morever reel-out systems let easily kitefarm configurations.

With a lever system of vertical axis if the kite is in high position there is a strong axial force instead tangential force (it is the same problem with train configuration of Kitegen carousel which for this point differs from reel-out systems);so the axis of lever system should be oblic.But an advantage of lever systems is to let only one flight configuration,so automatic piloting should be easier.

On orthokitebunch.pagesperso-orange.fr the tangential force is maximized (no (or low) radial force,and no axial force with oblic axis),like for an optimized reel-out system.The automatic piloting should be easier than on reel-out system (except for specific bunch of kites) but requires all the same an active control.

And it is also true that on some WPI or Kitelab lever configurations the tangential force is not maximized (so no needed large lever),but maybe no requires an active control,maybe passive control can be enough.WPI gives a value of one-Kw scale for a kite of 10 m² and wind speed less than 11 m/s (10 m/s).If you take Loyd's formula,Power = 2/27 density x kite area x cube of wind speed x CL x (CL/CD)² you can see a higher potential of 18500 W with wind speed = 10 m/s,CL/CD = 5,density and CL = 1 (for simplification),kite area also 10 m².
For me the low value of WPI is for two reasons:no maximization of tangential force (the tether is not perpendicular in the lever),and also horizontal axis for the lever which limits kite travel,so kite speed.

Flygens have the advantage to let a non mobile anchor,so no loss because of no downwind component;the losses are at the propeller (Betz'limit,output) (and also because of electrical transmission but it is another problem). 

It is not possible to have everything.
And it is not all:there are many of other technical considerations.We must also take in consideration economical aspects:generally for AWECS land occupation is low,but surface and volume airspace occupation are high.One objective of OrthoKiteBunch is the minimization of land and airspace occupation for a same amount of power...

PierreB

Pierre BENHAIEM schrieb:
I havn't given this very much thought yet, but here is what I can say
simply form experience with my own kites (which I used for sailing).

My stack of 6 large (4 m span) Flexifoils could easily pull 6 kN in a
moderate wind in a figure 8 downwind. If they can pull lines out at the
rate of 2 m/s that gives 12 kW, probably less than half that with losses
subtracted. Then you'd have to spend at least as long as the reel-out
time reeling in with the stack high overhead, probably longer, say with
10% of the power. So in the end you'd be happy to get an average of 1-2
kW. That wouldn't be so bad if it worked automatically and never
crashed. Until such control is implemented, a stationary turbine would
be easier.

When working in Dorset for Keith Stewart we built a balanced mechanical
two drum reel with a differential so that the main motor/generator would
be separate from the smaller control motor. Actually we worked them both
by hand. Worked OK but was quite expensive and still had a bit of friction.

Later working for Air Commodore Nance we had BP's old kite research boat
"Assessor". This had two large hydraulic winches. I managed to fly the
Flexifoils with them, but only just; the winches were too slow. It would
have been impossible to generate any power or even operate without
external power because of the large losses of the winches intended for
static kite systems. We also tried pulley systems but didn't get very far.

Theo Schmidt

Downwind composant is common for all groundgens but the "kept" power is yet very good.Power = Force x roll-out speed (see Pr.Diehl's paper);speed of kite v = 2/3 wind speed x CL/CD and force = 1/2 air density x area x CL x (speed of kite)².Power = Force x roll-out speed.So the "kept" power is yet 4/9.So power works with (speed of kite)².

With Theo's example wind speed would be 3 x 2 m/s = 6 m/s.If global area is 24 m²,if CL/CD is 5,5 (it is possible for a good kite) Loyd's
formula would give:2/27 air density x 24 x cube of 6 x CL (5,5)² which is very close of 12 KW you give.With static use the value will be 9/4 x 1/30.25,by far a lower value.Please correct it if it is wrong.

PierreB

"With static use the value will be 9/4 x 1/30.25,by far a lower value" precision:force value (For power a static AWE should carry a propeller)

PiereB

"A kite anchored at a single point follows a spherical geometry & is moving downwind some part of any sweep cycle, including sweeping flygens."

DaveS,

It is true,but it is a question of the average of downwind motion to let a motion of the conversion system.For groundgens no (average) downwind motion = no power:downwind motion is a useful ill.For flygens average downwind motion does not exist.

A short lever (with perpendicular transmission) is like a low unwound tether for reel-out system.Nor power = force x roll-out speed or if you want force x lever length for an equivalent motion.

However a short non perpendicular lever can have some advantages (possibility of passive control to study) but the price is a lower output.

"Dave Lang's report of Joe Hadzicki's AWE scheme has a kite cart that just tracks back & forth crosswind."
Is it the buggy scheme Dave Lang describes with other schemes?PDF]

Using Kites to Generate Electricity: Plodding, Low Tech Approach Wins

It seems (for me) that buggy's motion is downwind while kite motion is crosswind (and downwind).

PierreB

DaveL.   What is proposed is rapid short-stroke displacement with constant recovery is mechanically/electricaly/aerodynamically superior to long-stroke reel displacement methods, with long recovery cycles. We are presuming equivalent power in the abstract.   The best available KiteLab short-stroke no-reel demo right now is how a high-frequency fast "kick" by a membrane wing-mill will drive a loaded spagged flywheel at high speed, without any complication of a reeling control cycle. I'll do the video ASAP.    We need a well designed analysis & comparative experiments to prove the winning solution. If you have good evidence the reel method is best, lets consider it.   A good short-stroke power analogy comes from IC engines where short-stroke (wide-bore) displacement dominates racing engine design over long-stroke (small-bore).   daveS   PS Pierre, DaveL can correct me if wrong, but the "buggy" method in the old report is a crosswind concept.

Wind power finds two powerful foes
http://www.themoneytimes.com/20100827/wind-power-finds-two-powerful-foes-id-10126095.html

Officials Work to Resolve Wind Energy, Radar Dilemma
http://www.defense.gov/news/newsarticle.aspx?id=59879
By Lisa Daniel

Just how deep is the resistance?  How will AWECS stand the scrutiny?

Solutions? 

 

Work with the DOD, Military, FAA.

Spacecannon


---- Joe Faust <joefaust333@gmail.com

Hey Dave.

The 'winning solution' may not be the one that is commercially viable. Short strokes are certainly attractive - for a time we'd considered linear generators and strokes of only ten feet or so, and haven't totally ruled that out in the future (when linear generators are available off the shelf). But remember that race car engines last only a few hours between rebuilds while long stroke diesel engines regularly survive for more than 15,000 hours. Yet even 15,000 hours is still less than two years of continuous operation. Many BIG marine diesels which run continuously for months at a time (fewer on-off cycles) have more than 100,000 hours of operation.

Number of power cycles and the repeated stress they impose may be the commercially practical limiting factor in any AWE system. Too frequent replacement of any AWE system components will make the system commercially impractical by increasing O&M and downtime. Even Makani's looping tests showed a clear 'cycle' of increasing and decreasing load on each loop (watch the power meter). As we all know, it's the flexing that breaks things.

Because of that, we're pursuing maximum reel out with very quick recovery to induce minimum wear on the entire system. I think KiteGen's demonstrated kite recovery method is brilliant (wish I'd thought of that). Like Kitegen, our hope is that with a long pull cycle of 30 seconds or more and a recovery half that, our overall duty cycle will be pretty decent, while reducing the total number of power cycles per year. A power cycle every minute is about 500,000 in a year. A power cycle every ten seconds may induce unexpected failures and require equipment replacement and more downtime than is economically practical for a commercially viable AWE system.

- Dimitri

"Even Makani's looping tests showed a clear 'cycle' of increasing and decreasing load on each loop (watch the power meter). "(Dimitri).
The delivered power of a crosswind kite (eight-pathes,looping-pathes,all pathes) is not regular.
Towards grid connection a smoothing device is needed for reel-in phase but also for reel-out phase,and for most AWECS,excepted (maybe) in the case of planning AWECS-farm,excepted also for Kitegen carousel configuration where the velocity of the rotation is regular.

PierreB

Doug wrote:
It's not an energy crisis, but rather a crisis of several effects all
going in the wrong direction:

1) People are producing more, not less, carbon dioxide and emitting
other potent greenhouse gases, also removing CO2 sinks like rainforests.
Therefore the climate is hotting up, leading to higher sea levels, more
flooding and droughts.

2) This leads to loss of arable land and food as well as places to live.

3) People are increasing in population and many are becoming more
afluent. They want more meat and milk, which again uses up land, removes
forests and increases greenhouse gases.

More people and less farmland, it's just not going to work. Then there
are lots of supplementary problems, like rich people growing crops for
fuel instead of for food.

Therefore we must use less energy and substitute fossil-fuel produced
energy with renewables. It's not a crisis and may never be a crisis. But
hundreds or thousands of people are every day losing their homes,
livelyhoods or even lives because of these things. Therefore every bit
of improvement we can do in the energy sector will help somebody.

Theo Schmidt

One more reason for Superturbine(TM) arrays.
radar-friendly
Ah, but who cares about huge breakthroughs?
Just give the government an unlimited line of credit and don't hold them accountable for trying, developing, or implementing ANYTHING.

Racing engine design is all about increasing valve area to make the most use of limited displacement.  Truck diesels are designed  for compact dimensions and maximum efficiency.  Relative stroke length does not mandate longevity, it is just something to be designed for.

Probably the easiest way to deliver steady power is to use several kite systems, unsynchronized.  However, the real need is for power on demand, so it might be better to use the kites to pump up a reservoir, and make hydro-electricity as needed.  Lever systems can be adjusted to change the stroke on a piston pump according to wind strength.

Bonjour Pierre,

I didn't intend to imply anything about the final power output. There seem to be a variety of ways of 'smoothing' that. I'm more concerned about long-term survivability of a tethered glider cycling between no load and more than a ton every minute. While beefing-up steel to a suitable size might work (if the financials come out right) for the ground based components, it's difficult to do the same for the materials the flying vehicle is comprised of. i.e. potentially very short service life of those flying components.

So back to Dave S's question about which might be better, long-strokes or short-strokes, I contend that long strokes will allow the components of any given AWE system to survive in-the-field longer. And for a commercially viable system (if that's what we're shooting for), long-term field survivability and the lowest possible O&M costs is what will eventually win the day.

- Dimitri

Dave Lang,

Thank for the indication"PS My understanding of Joe Hadzicki's "Buggy"is that it moves perpendicular to the wind as the kite move "cross wind"."

So with this buggy scheme no downwind component (?).I try to translate this scheme into a lever scheme,then a reel-out scheme.

-Translation into lever scheme:it would be like a tether extending the lever (such a way has been described) instead of a tether perpendicular in the lever;normally only radial force,no tangential force but with tension the tether is a little like a stiff bar or an additional lever in the same direction.How is it possible to calculate the (tangential and parasitic) forces in respect to the value of tether tension and length?

-Translation into reel-out scheme:drum (winch) perpendicular in the wind (instead of the average direction of the wind _ and the angular move in respect to the kite move _ ).The tension of the tether has no positive utility,and nobody uses reel-out system of such a way.

Buggy scheme would be closer of that described way of lever scheme:the tension of tether would let cross motion of buggy.

I have not enough scientific knowledge and it would be interesting for me and maybe for others you post some didactic messages.

PierreB

Dimitri,

Kite power not being regular,do not you think that irregularities could be comparable in strokes?A long stroke would be then an addition of several small strokes,and mechanical contrainsts would be identical. (I have no response of it).

PierreB

To all:

Way back in December 2008, I submitted a request to the FAA which essentially asked for clarification of, changes to, or exemption from the FAA rules regarding "moored objects" (Title 14 CFR chapter 101) for our AWE system testing. We'd specifically requested to fly in only class G airspace, below 1200 feet, and more than five miles from any airport. We'd further requested that we could fly at night and in clouds, but utilize the same type of small and light-weight anti-collision lights used on sport aircraft, instead of the much brighter but 80 pound lights required for towers (and balloons flying at night).

It took awhile (2o months), but a few weeks ago I received a response from the FAA, from Elizabeth Ray - director or Aerospace and Aeronautical Information Management at the FAA. Elizabeth happens to be one of the scheduled speakers at the upcoming AWE conference, so it may be safe to assume that she is well versed in what we're ALL trying to accomplish, not just my request.

Unfortunately, my request was denied, on all counts. Interestingly, in reference to the article Joe Faust circulated a few days ago, she also mentioned the FAA's concern about radar interference.

Soooo . . . . that's one down and two to go. Hints in the rejection seemed to point toward the FAA's preference to consider an AWE system as I described to them, as an 'obstruction' rather than as a 'moored-object'. I've heard from other people that they have discovered the same preference and I hope Elizabeth will shed some light on this in the coming weeks.

The other alternative is to have AWE be considered 'tethered-UAS', which seems logical, but apparently will involve a few too many hoops for us to all jump through, especially as they're just getting their rules about non-governmental UAS worked out now. Again, I hope Elizabeth can help to clarify the simplest path for AWE systems to be fully accepted by the FAA.

- Dimitri

Dimitri,   Long-term survivability is a complex function of many factors. Your system requires reliably reeling in & out over a long life, which introduces several failure-modes absent in a shorter-stroke system that does not reel.   Even if you are right that UHMWPE somehow has a short cycle-life, replacing kiteline as needed for reliability may just be reasonable maintenance compared to the risk of total loss of your kite-glider in a reeling malfunction.   Have you have calculated your engineering trade-off in light of added reeling failure-modes?   daveS

Hmmmm.
If you mean by "irregularities", gusts and other rough wind, you may be right. At least for a system that may be victim to such winds.

Our glider design automatically compensates for gusts, keeping the tether load within the range we're targeting for the particular operation - climb, descend, power-pull, etc.

But even without that, I would 'think' the difference between a 9000N power-pull and essentially no-load (on retraction or 'floating'), would be considerably more wearing on the system overall than the difference between a 9000N power-pull, plus a little more from a sudden gust. (I like to imagine these forces as hanging a car from a tether and raising it off the ground, then setting it back on the ground, once every minute. You're suggesting adding a few shakes while it's being lifted and hanging there. I'm not sure those shakes would matter as much as the lifting itself.)

But until we get something working with forces like that and able to run automatically, continuously for a few months, it's all speculation. N'est-ce pas?

- Dimitri

Cyclic irregularities like this:"Even Makani's looping tests showed a clear 'cycle' of increasing and decreasing load on each loop (watch the power meter). "(Dimitri).

PierreB 

Thanks Dave, but I never suggested Dyneema might not hold up. You suggested that. I'm more concerned about the vehicle in the air.

Much of the stuff on the ground WILL require frequent (hopefully less than annual) replacement. We've done some, and will continue to perform engineering trade-off analysis for the various components to determine whether 'buy' will work or 'build' is required for beefier components to meet the longevity requirements. But I'm sure it will take many years and hundreds of systems in the field before we really know what's going to break, when.

It's the cost of replacing the vehicle in the air that will make or break this business. As I described to Pierre in another post, imagine a car hanging from a tether lifting into the air every minute. Now replace the car with a light-weight flying vehicle with a ton of sand bags on it's wings. Lift that puppy 500,000 times and see what breaks first. Beef it up. Do it again. Etc. Hopefully when we're done, the vehicle is still light enough to fly in low-enough winds that the business-case is still viable.

And that's just to produce a continuous 30kW or so. Hang an M-1 tank from a tether and lift it every minute to simulate a 1MW system. I wish those pursuing that much energy production good luck, but I'll leave that up to others.

- Dimitri

EXACTLY ! You could see the glider speed up and slow down on the loops. Hopefully they'll eventually develop fine-enough flight controls to minimize the tether pull on the faster portions of the loop to reduce the load on the glider. And eventually, with a few thousand feet of tether out there, the loops will become large enough that their frequency will decrease, reducing the total number of cycles per year.

- Dimitri

Viewing the numerous videos from Makani, Laddermill and now Windlift in the last few weeks, it's struck me that all these systems, when producing power, are flying extremely low in the sky.

Yes, I know we're all early into this and we're expecting much longer tethers and commensurately higher altitudes, but, , , , if the thing's only flying 200 feet above the ground, why not just put up a wind turbine?

Unless . . . is the Makani glider able to produce reasonable power in locations with steady near-surface winds considerably lower than wind turbines? i.e. is the looping in low winds the equivalent of a wind turbine in high winds? (In which case the value proposition for fly-gens changes from "high-altitude wind harvesting" to "low-wind energy harvesting". Which would frankly make all of our lives easier.)

Or will these systems all require a tower to fly from the top of to get higher into the atmosphere without a mile of tether? In which case the value proposition gets very, very fuzzy.

- Dimitri

Dimitri,   Thanks for the details regarding your FAA request. The message is much the same as Joby got, either conform to aviation practice or be relegated to the margins.   Even if AWE airspace is classed as an obstruction, our aircraft will still be subject to the same safety-critical standards of airworthiness to the extent populations & personnel are exposed to hazard. There will be no magic short-cuts in those countries with highly regulated airspace. On the other hand, remote oceans & many developing countries are pretty much open for risky evasion of flight standards.   Enforced compliance with aviation norms favors AWE players with strong aviation backgrounds. KiteLab Group seems to be the best of any AWE start in this regard & will be soon disclosing the blue-ribbon circle of aviation partners & consultants that have guided its vision. Any AWE start-up weak in aviation culture is invited to develop under KG's umbrella & also attend-   Kite Pilot School   daveS