Flying kites deliver container-sized power generation

https://spectrum.ieee.org/micro-wind-power-kitepower

by geox • 3 years ago

211 170 3 years ago

spectrum.ieee.org

Gotta be more to it. They blithly say, reeling it in takes a fraction of the energy it generates when it pulls the line out. But that's nonsense on the face of it.

I'm guessing, it changes it's wind profile, maybe going edge-on or closing up, to make it easy to pull down again. Gotta be something.

greesil• 3 years ago

I think the kite might have control surfaces, thus would be able to control lift by changing its angle of attack.

cjbgkagh4• 3 years ago

Trailing edge control lines, pretty standard. You let them out and the kite will no longer be able to catch the wind and will float down. Keeping some tension on those lines and wenching it in will keep the kite controllable.

datadrivenangel3• 3 years ago

Brake lines on a traction kite like that can cause the foil to fully de-depower and fall out of the sky. So you can let the wind pull it up, and then let gravity bring it down.

jdiff3• 3 years ago

Only as much nonsense as rowing a boat without taking the paddle out of the water. In that specific example, you're going to be going in circles, but you will be moving.

pacaro• 3 years ago

You can propel a boat forwards with only one oar, without lifting it from the water. It's a useful skill, Kayakers use the same stroke to move sideways, and for stability in rough water. See https://en.wikipedia.org/wiki/Stern_sculling

LazyMans• 3 years ago

On its face it sounds silly, until you get experience with wind surfing. It's using the same concept. Figure 8s generate the pulling force. When you stop the figure 8s, and change the angle of the kite, you get minimal pulling force.

pierrekin3• 3 years ago

Reeling it in takes a fraction of the energy it generates when it pulls the line out. But that's nonsense on the face of it.

Why is this nonsense on the face of it? This is just how kites work. Do you imagine that kite surfers just overpower the kite with their might and pull it back to the ground when they've had enough?

JumpCrisscross• 3 years ago

It’s also how turbines work. The fluid pushing on one side isn’t cancelled out by the drag created on the other.

JoeAltmaier2• 3 years ago

No. I said I didn't. I said I believed there was more to it.

Others have actually elaborated on the likely mechanism. But sure, mocking people is a kind of post I guess.

jollyllama• 3 years ago

The energy generated by the system while reeling out is greater than the energy consumed to reel the kite back in.

There's something about it that just triggers the "perpetual motion machine" identification heuristic.

zardo2• 3 years ago

On a multi line kite you can control the angle of attack and speed. That gives you the ability to dial the pulling force up and down over a large range.

bentpins• 3 years ago

You're not wrong - they do that.

Have a look at https://thekitepower.com/products/ There's a diagram of the flight path and power generation over the cycles.

The flight path on the way out is much much longer going cross wind in figure 8s. On the pull back in it's a direct path back in, and it looks the kite shifts to point back at the base station more so there's a ton less resistance than on the way out.

jitl• 3 years ago

I’m happy to see this idea continues to develop. I was worried its failure was foregone when Google shuttered their moonshot Makani in 2020. It seems like this iteration is simpler.

SCM-Enthusiast• 3 years ago

for some reason, this always happens with the google moonshots; They come at it from the wrong angle. Someone comes along with a slightly simplier solution after google scrapes the whole thing as uneconomical or beats them to the punch on using a far more technical solution. Don't seem to have a big "Cost per KWH" KPI's internally nor a sense of urgency.

pfdietz• 3 years ago

I wonder how Malta is doing. The News blurbs at their website seem... ok?

skyleradams• 3 years ago

Not to be a HN naysayer, but wasn't this tried already with Makani Power?[1] They even made a documentary about it[2]

Compared to traditional wind turbines, this solution trades an enormous amount of complexity, maintenance, etc for small reductions in material cost. We should be churning out traditional wind turbines for cheap instead.

[1]https://x.company/projects/makani/

[2]https://www.youtube.com/watch?v=qd_hEja6bzE

jdiff3• 3 years ago

The article poses a different use case, replacing diesel generators for off-grid power, not hooking into the grid to replace turbines.

cjbgkagh4• 3 years ago

This is a very different approach. The google approach is making an airplane fly in circles generating continuous power, this slowly lets a kite out then reels it in generating pulsed power that would need a battery to smooth out. This approach can use pretty standard kite technology which is far cheaper than airplane technology.

jacquesm3• 3 years ago

Use multiple kites in a staggered pattern so one of them is always generating near peak power. That complexity of course offsets all of the gains, but that's fine because it illustrates why this is an idea that just won't fly.

Vvector3• 3 years ago

The article indicates that it comes with an integrated battery.

rtkwe• 3 years ago

It'll make sense in some places where it's harder to build/deploy a 40kW traditional turbine. They're not easy to move and are relatively close to the ground so they are viable in fewer places than kite systems because winds aloft are much higher than those near the ground. You can also use this temporarily in areas where you have periodic power requirements and poor access to the wider electric grid. Think about deploying a lot of these in areas right after hurricanes or other disasters.

ksenzee• 3 years ago

Not to be flip, but the fact that Google canceled a project doesn’t say a whole lot about whether that project was viable.

jacquesm3• 3 years ago

The fact that Google funds a project isn't evidence that it is viable either.

patall2• 3 years ago

Not to be a HN naysayer, but wasn't this tried already with Makani Power?[1] They even made a documentary about it[2]

So? These (kitepower and skysails, but there are more) are long standing 'competitors' of Makani, all existing for far longer than 2020 when Makani went down. Just because Google gave up, not everyone else also gave up. I mean, Google also stopped Google code, groups and google+, yet similar products are still triving.

datadrivenangel3• 3 years ago

60 square meters of kite surface area is a lot of pull. 5 square meters can be enough to pick up 100kg in the right wind conditions.

helpfulContrib• 3 years ago

A sailboat typically flies about 5 - 8 square meters of material in the sails, pulling 3 - 4 tons of material around the world ..

pierrekin3• 3 years ago

This doesn't seem right to me, in my experience a 3 - 4 ton sailboat is around 9m long, which has a sail in the 20 - 40 m^2 range.

A 5 - 8 square meter sail is really teenie tiny.

usrusr2• 3 years ago

Robotic boat, a large tank, some power-to-storable tech, a power generating turbine beneath the waterline and a huge kite. Just send it out on the oceans, to cruise aimlessly wherever the satellite uplink suggests favorable weather and have it head home when the algorithms assumes that remaining tank capacity might get filled up on the way back. Most attractive post-fossil future ever.

Unfortunately, unattended power-to-anything is very much a far away dream, despite all delusions of being able to do it large scale on Mars. All other technology is basically ready to go, and the "lateral lift" of a fast-moving boat is a perfectly adequate substitute for mooring when it comes to tapping wind on the high seas.

IshKebab• 3 years ago

Based on the numbers from the article: 40 kW * 80 s / 500 m is 650 kgf.

So maybe it will work. Still I feel like as soon as you get a moment of calm it will all break. The wind may be very reliable in places but is it ever so reliable that you don't get moments of calm for hours at a time?

pierrekin3• 3 years ago

When there is a break in the wind, you reel the kite in, creating apparent wind.

datadrivenangel3• 3 years ago

The diagram envisions the kite also being connected to a battery, diesel generator, and solar PV installation.

The real question is not if the kite installation or renewable installation is 100% reliable, it's a question of how much does it cut your total diesel consumption. US military loves renewables because it reduces the amount of fuel they have to move.

boringg• 3 years ago

Operating the kite isnt easy on its own. A lot of complexity involved in this. I am intrigued as someone who kites and develops clean energy. I have a tough time seeing how this is a set and forget situation. Maybes it the first step in a direction with something better down the road!

Gys• 3 years ago

After the tether reaches its maximum length, the ground station winches the kite back in. Though the Hawk must expend energy for reel-in, it only expends a fraction of the energy, resulting in a net energy gain that varies by wind speed. An entire cycle takes about 100 seconds: 80 for reel-out and 20 for reel-in.

This is an interesting approach. Also, the kite is doing eights all the time. Although I suspect that is only while reeling out.

tonyedgecombe• 3 years ago

Presumably they can adjust the attitude to make it easier to real in.

brlewis2• 3 years ago

My recollection from flying kites a long time ago is that operating a kite gets easy after a certain height. I imagine the Kite Control Unit (KCU) can easily keep it aloft once it's high enough. The tether is 352m long according to https://thekitepower.com/the-hawk/#components

nothercastle2• 3 years ago

I don’t think you can make a kite that can last a decade of load. We just don’t have materials strong enough. Also you need a sophisticated algorithm to fly it and never crash

dtx1• 3 years ago

As someone who regularly flies hobby kites, I think it can be done.

Modern kites are made of nylon and kevlar. With regular maintenance these kites should last at least a decade. Cables might have to be replaced every few years.

As for the flying algorithm, I doubt it has to be very sophisticated at all, especially if the kite is itself designed to self right and stabilise. After all, a single line kite has 0 controls.

nothercastle2• 3 years ago

I sort of assumed it would power and depower like a kiteboarding kite to create work. You could probably depower by collapsing the kite leading edge and dragging it back in but that seems less efficient than flying it in a figure 8 to power and depower.

smusamashah• 3 years ago

How is the kite raised initially and what happens when air stops, how is it re-raised?

Reading the article seems like it's pulled back if air is stopping, and slowly released based on air speed perhaps.

cjbgkagh4• 3 years ago

On islands where this is targeted the winds are usually very predictable, especially at higher altitudes. This isn't like flying a kite at ground level, there is no need to wench the kite back down to ground level, just up and down where the faster high altitude winds are.

timdiggerm• 3 years ago

All of the raising is done by the wind.

tamimio6• 3 years ago

I wonder how they will deal with bird attacks. Falcons and eagles (ironically, they share the same name with this kite) are territorial and will go after these drones. I once had a huge heavy-lift drone that got attacked too. But with a pilot nearby, the easy solution is to fly to a higher altitude, that seems to determine who rules the sky in their eyes apparently. I’m not sure how this kite will manage such situation.

patall2• 3 years ago

By being 60m2 big? I mean, helicopters are also not being attacked by eagles, why would this kite be?

adrianmonk• 3 years ago

Wind power machine idea #1: turbines.

Potential concern with idea #1: the machines may kill birds.

Wind power machine idea #2: kites.

Potential concern with idea #2: birds may kill the machines.

smileysteve4• 3 years ago

The bright side is that wind doesn't tend to stop as much 325m up

Vvector3• 3 years ago

People cannot be anywhere in the radius of the kite cable. Kinda limits where is can be deployed. But the quick deployment could work for some situations.

brlewis2• 3 years ago

Details: https://thekitepower.com/the-hawk/#space_requirements

shkkmo2• 3 years ago

This is not correct. Untrained people can't be inside the flight zone while operating. This is roughly the downwind quarter of the potential flight zone.

Vvector3• 3 years ago

Even a quarter is a huge area. Using the "safety buffer" radius of 425m, that is 560k m2 or 140 acres. A quarter of that is 35 acres, for 30 kW.

For regular wind turbines, it's 30-70 acres per MW generated. That is 20x-40x more power for the same land area. And almost all the land under a wind turbine is freely usable.

krisoft• 3 years ago

Untrained people can't be inside the flight zone

What kind of training makes you immune to being sliced in half by a tether?

MostlyStable• 3 years ago

Are these less visible than traditional wind mills? If so, maybe they could be used at sea and get around the hatred of wind power as an eye sore.

tamimio6• 3 years ago

You can probably deploy it inside the solar farm, most of the times these aren’t open for public to wander around.

antisthenes2• 3 years ago

So it's just a really big battery.

The kite thing is just a novelty/marketing move. There have been containerized commercial battery systems available for at least a decade. The barrier to adoption is, as always, price, not "kite delivery".

Is this for really remote places, like Greenland/Alaska? Because otherwise you can just use a truck/tractor.

123pie123• 3 years ago

I'm surprised other ideas have not taken off yet?(intended)

although not really a kite, this looks promising : https://www.youtube.com/shorts/zGGn-HY1jak

brazzy• 3 years ago

You completely misunderstood. The kite is not for "delivery", it actually generates the power.

antisthenes2• 3 years ago

Yes, you're right. I'll have to re-read the article to see how much this kite can actually generate.

qnsoaejacniln3• 3 years ago

How will this work with aviation? I know it probably won't affect most IFR flights, but still possibly dangerous for VFR. Will there need to be a new restricted area for each deployment?

nameless912• 3 years ago

Depending on the altitude, they could keep these within class G airspace, which means VFR's job is to see and avoid. I think that's a pretty defensible solution as a pilot who spends all of his time in VFR operating in Class E/G airspace.

tamimio6• 3 years ago

A project I did a couple years ago was to have an onboard SDR that communicates automatically with airplanes in the vicinity, or switching to manual where the drone operator can communicate as if they are “on-board” through the internet by a mic on ground. I can see something like this is doable, with a modified system to fit the length flight, after all, the position is fixed so I don’t think it would be a problem.

qnsoaejacniln3• 3 years ago

Just wondering, how were you communicating to the airplanes in vicinity?

Radio would require the planes to be listening on a specific frequency and ADSB Out would require the planes to have ADSB In which is not guaranteed.

Nick87633• 3 years ago

At first look, it seems like simply by having so much less mass of material involved that you have a good head start at competing on LCOE, even if the system needs the kite and tether replaced every 5-10 years.

I think the biggest roadblock would be making sure it can return to the perch with high reliability otherwise you will have a lot of service calls for kites that landed on the ground.

nirolo• 3 years ago

There's been a recent video by the German "Sendung mit der Maus" (basically how does stuff work for little children) about these kind of generators. I did not double check if the company in the video is the German one mentioned in the article, but chances are high. Video and subs are in German only, but it's less than 10 minutes and one can see a little how it works.

https://m.youtube.com/watch?v=aqfFZDWiJOI

NullPrefix3• 3 years ago

Why are these people wearing safety helmets? Does this imply that everyone living under the kites will have to wear one too?

IanCal2• 3 years ago

They're under a crane lifting stuff up overhead on a work site, that's probably why.

sambazi• 3 years ago

no, it's because the are directly at the site where the kite is launched (and on national tv)

Cthulhu_• 3 years ago

I doubt people will be living under the kites. I doubt there can be anything in the vicinity of the kite flying range for that matter, so no windmills or high tension lines or buildings or anything, which limits this thing's options especially in higher density countries like NL.

dtgriscom3• 3 years ago

Very cool. I noticed that the radio-controlled unit that steers the kite has its own little wind turbine for power.

tamimio6• 3 years ago

I wish if there’s an actual video of the whole system being operated and not just 3D renders, a lot of questions in mind about some details but probably most of them will be answered in such video.

jimmySixDOF• 3 years ago

I can only imagine how many 3D models they render in a physics simulation platform like Nvidia Omniverse so they likely just used what they already had.

mikepurvis• 3 years ago

I've always loved this idea since hearing the Swift Navigation founders talk about it in their Kickstarter video: https://www.kickstarter.com/projects/swiftnav/piksi-the-rtk-...

Glad to hear there are people still working on it.

sytse• 3 years ago

This is the best article on the problems of airborne wind energy. It is 10 years old but I think Michael Barnard did a great job explaining all the variants and why it is hard https://czmphorfqgktmzxu.quora.com/Airborne-wind-energy-a-co...

michaelbuckbee• 3 years ago

You were not kidding. That article really covered a lot of the obvious questions I had (and was the single best thing I've ever read on Quora).

Scea91• 3 years ago

Interestingly, the very first statement is quite misleading. The statement:

On average, a humble wind turbine uses less land area per megawatt-hour than almost any other power source.

The article itself refers to this citation [1]. It says, unsurprisingly, that the most land efficient power source is nuclear. The statement is of course technically true because it says "almost any power source".

With wind, however, even that is tricky because you can either count just the area directly below the turbine body, which is still higher than nuclear and unreasonably optimistic because you severely limit a far bigger area. If you count also the spacing (too pessimistic on the other hand because part of the land might be used for farming) then wind farms range across the whole scale of land efficiency.

I think its fair to say that land use of wind farms is "complicated", but saying its almost the best in this regard sounds like manipulation.

[1] https://ourworldindata.org/land-use-per-energy-source

londons_explore4• 3 years ago

Wind turbines can be built big enough that the blades, at the lowest point, are higher than almost all other land uses, except perhaps forestry.

To be honest, the access roads are probably the biggest real impediment to using the land around a wind turbine. Can't exactly farm millions of acres of corn with robotic combine harvesters with a criss-cross of access roads to the base of every turbine.

kingkawn• 3 years ago

Why not? Seems easy to teach the robots to not harvest on the road

jeffbee2• 3 years ago

And yet. https://www.google.com/maps/@43.0700265,-95.6508704,3a,60y,9...

mista2nith• 3 years ago

Midwestern farmers very much disagree with that “impossibility”

m4rtink• 3 years ago

I'm not sure robotic combine harvesters are a real concern (yet ?) - modern "manned" harvesters are already crazy effective and fast & I've seen them navigate some pretty crazy field geometries at times, so I'm sure they can handle a straight road.

klyrs• 3 years ago

Can't exactly farm millions of acres of corn with robotic combine harvesters with a criss-cross of access roads to the base of every turbine.

You certainly can; single-objective suboptimality is not the same as impossibility. But perhaps this would be an excellent use-case for heavy-lift dirigibles.

zensavona• 3 years ago

Sounds like the article used just the right wording then.

“…less land area per megawatt-hour than almost any other power source.” As I read it this implies there is one (or some very small percentage) power source which uses less land per megawatt-hour, which is exactly the case.

psd15• 3 years ago

Tidal energy.

saulrh• 3 years ago

An offshore wind farm by definition uses no land area :V

itishappy2• 3 years ago

Aircraft carriers suddenly looking competitive...

OtherShrezzing2• 3 years ago

I'm wondering if the OWID data takes the 3,400km^2 of exclusion zone from Fukushima and Chernobyl (more like 5,000km^2, see below) into account when calculating the average size of a nuclear plant?

I think if we're saying the space beneath the blades can count towards aggregate wind-power land use, an argument can be made to include nuclear wasteland in the aggregate nuclear-power land use.

soperj2• 3 years ago

Chernobyl's exclusion zone is 4143km^2, and Fukushima's is 807km^2.

s0rce• 3 years ago

Shouldn't you include in the average nuclear sites that didn't explode?

xyzzy_plugh• 3 years ago

Of course it doesn't. We don't build nuclear generators with pre-approved unusable exclusions zones. This is a ridiculous suggestion.

Should we consider the potential blast radius of the catastrophic failure of wind turbines as well?

You literally cannot build structures in the path of a wind turbine if you want it to function.

worik• 3 years ago

It says, unsurprisingly, that the most land efficient power source is nuclear

Not true if you factor in waste storage and the time to store it

Long after all the nuclear energy has been used making your toast, and long after many cycles of climate change, you will still be storing hi level nuclear waste, and monitoring it.

But who cares about tomorrow? Party on, and let future generations pay!

ClumsyPilot3• 3 years ago

How does this calculation work?

Take simple chemical pollution, for example with lead - as far as I can tell, it stays around forever and we,ve poisoned vast landscapes with it during mining coal copper for example.

Or take simple industrial waste , say wind turbine blades, they go to landfill, sure they aren’t hurting anyone but there are a lot of them- does it count?

frankthepickle• 3 years ago

looking at the article, you're really splitting hairs - wind and nuclear are 0.3 and 0.4km2, many of the others are 20+

if you were to ask someone based on that if wind was one of the techs that use least land, it's an obvious yes.

I think you're being more disingenuous than the article..

dukeofdoom• 3 years ago

why not a blimp?

Come to think of it, I'm kind of curious why a RC blimps have never become popular. I own DJI drones. But no blimps.

Abekkus• 3 years ago

Helium supply is an issue and blimps are risky in adverse weather. Also these kite models keep the generator on the ground, saves from trying to float so much delicate weight.

jrockway• 3 years ago

Interesting! I always try to guess how these things work before I read the article. My imaginary design would have the kite pull a heavy weight up and as the weight moves, it rotates a generator. When the weight reaches the end of the travel, it falls back down and the cycle repeats. The flaw with this design is if the wind was strong enough to pull the weight up, then the weight is not going to be able to fall back under its own power. That's why the real design just uses a motor to do that. Makes sense!

6gvONxR4sf7o• 3 years ago

I used to work on this at a different company, and I'm glad to see work on it continuing! It's one of those things where the physics works out really great for fantastic power generation, but the engineering is just so damned complex, so it's tough to... get off the ground.

londons_explore4• 3 years ago

I think the Google approach suffered from too much engineering. Specifically they had sunk too much money and too many people at very expensive prototypes before they'd gotten the design even close to running reliably. As soon as you become a big team, you become less nimble - which isn't what you need when your product still has big unknowns.

They should have started with five 2 guy teams, a year and a budget of $50k each, and tried 50 different ways to get a scale model that could reliably not crash in all weather conditions for a few months on end.

Only when you have a craft that can either survive all weather, or reliably pack itself away whenever the weather changes quickly, then figure out how to scale it up and make it generate power.

thechao• 3 years ago

The back-of-the-envelope analysis for kite-based power is very compelling; enough that I tried my hand at designing a kite-powered system in ~2004. I don't think anyone can really appreciate how challenging the engineering (control systems) are for all-weather kite-flying until they just try to reel-in & reel-out a kite on a relatively calm day. I literally couldn't even write-down the differential equation which describes the inverse control path for the kite, when there's one vector for the kite, and one vector for the tether, under the reel-in load; none-the-less, solve the equation, and then get it to work with a freakin' stepper motor.

trefn• 3 years ago

I wonder if you could make the kite itself lighter than air to avoid issues where the wind dies down? E.g. a kite shaped airship.

usrusr2• 3 years ago

There are no issues, at least as long as you can supply power to the base station: just make the motor/generator reel in the kite, that causes plenty of movement relative to the stationary air to keep it afloat and controllable right down to the reefing mechanism.

dandrew5• 3 years ago

Is there anything stopping them from adding a turbine system to the kite that would continuously spin (when there's wind ofc) instead of reeling it in/out?

smileysteve4• 3 years ago

That increases costs because now you need transmission lines down to the kite instead of only the dyneema lines for control.

soperj2• 3 years ago

Why would they ratchet the kite in instead of making it dive and quickly winding the cable in? Should be easy enough with software right?

smileysteve4• 3 years ago

Stalling is more controllable than diving

purpleidea• 3 years ago

How long does the Kite and Dyneema rope last before either breaks and one or both need replacing? Their site https://thekitepower.com/the-hawk/#space_requirements mentions the lifetime for the battery and ground station, but I'd be most curious about the durability of the whole system.

dendrite9• 3 years ago

I suspect looking to sailing would get you the best answers as an outsider. Dyneema ropes are used for sailing but I don't know about the replacement rates, or if they are replaced preemptively for racing where the risk of an issue after some use is too expensive and replacement is cheaper. I have have seen lots of parachute or hot air balloon fabric offered because companies have a limited number of hours of use before they retire them.

russellbeattie• 3 years ago

After seeing Big Hero 6, I've always wondered about the feasibility of giant floating blimps with generators...

Aeroi• 3 years ago

As a longtime kiter and sailor, the durability of the kite and line system seems to be the biggest weakness. Constant uv exposure and stress to these systems would make the economical calculations interesting. I don't know of a current setup that could see sustained continuous use for 1 year without significant material replacements or maintenance...

UncleOxidant2• 3 years ago

I worked at a small kite power startup in 2019. Unfortunately we couldn't secure funding to keep operating. It became quite difficult to secure funding after Google suspended their Makani moonshot project - potential funders were like "well, Google got out of this so why do you think we should fund you?". (though our kites were much smaller than Makani's and we didn't need a huge amount of funding to keep developing)

It's a very difficult problem keeping a kite flying in a figure 8 pattern allowing it to rise to the end of the tether and then effectively stalling it to pull the line back in - repeat over and over and while you're at it try to maximize power output for the weather conditions (and then there was the problem of automatically launching - we were leaving that for last). We were starting to look at reinforcement learning for the problem, but it was going to take a lot more data and a very accurate model of our kite and weather conditions.

Definitely one of the more fun jobs I've ever had even if it was short-lived.

behnamoh• 3 years ago

potential funders were like "well, Google got out of this so why do you think we should fund you?".

Google shuts down projects and products because it's Google and can't productionize ideas. It's sad that this results in such secondary effects.

tschwimmer• 3 years ago

I know nothing about kites but as someone who currently works at Google and knows a bit about how projects are funded, the first argument doesn't really make a lot of sense to me. At Google's scale, a materially impactful opportunity needs to have the opportunity to generate billions in revenue and have high margins. That's just a function of Google's size and opportunity cost (people can otherwise work on Ads, Cloud, etc). However, just because something isn't a Google business for Google doesn't mean there isn't an opportunity for a (very) profitable or successful business. Sounds pretty weak - perhaps the VCs you guys were pitching to were more focused on SaaS vs hard tech.

UncleOxidant2• 3 years ago

I think they saw Google's decision to defund Makani as a sign that kite power wasn't viable. We certainly weren't in the same league as Makani - their "kite" was essentially a largish 4prop airplane. Google must've spent in the several hundreds of millions on that project. Our prototype kites had a ~8' wingspan and we were operating on a shoestring budget.

ugh123• 3 years ago

Did you guys look at boats/maritime as a potential market? Would sea winds make certain things easier? Harder?

scblock• 3 years ago

Article needs an editor: "As of late 2022, the world contained about 900 megawatts of wind power capacity." I've worked on single projects larger than that. Presumably they mean gigawatts?

dtgriscom3• 3 years ago

900GW it is: https://en.wikipedia.org/wiki/Wind_power_by_country

samstave• 3 years ago

Have you folks ever heard of a company called CAT?

They tend to make things for pushing around dirt.

So, TEU containers are TINY. What if - we used an army of CAT-like dirt movers in key areas to FUNNEL wind through a bunch of "wind-tunnel" type things and feed higher power wind in the directions we prefer?

Maybe call it "planetary vehicular land transmogrifcation" - or "terra-forming" for short?

psd15• 3 years ago

That would be both interesting and cool, but I suspect you'll find it extremely uneconomical use of land, and wind is less energetic at ground level. Maybe if this "CAT" company builds machines that can operate at a few hundred metres of altitude...

xg15• 3 years ago

It's an amazing project, but, out of curiosity: Why do all the AWE projects except Google's seem to use the reel-in/reel-out approach and don't attach turbines to the kite itself? Reel-in/reel-out seems a lot more complicated, power inefficient and taxing on the material than just having the kite up there (semi-) permanently.

I assume there are some technical reasons why turbines are less practical, but could anyone explain what those are?

fwip• 3 years ago

I only have wikipedia-level knowledge, but my understanding is that turbines are heavy, and wind power spent holding the turbines up is power that isn't converted to electricity. If you want to put the turbine up high, you can save power by just building a traditional fan-on-a-stick wind turbine.

ClumsyPilot3• 3 years ago

This is wrong in physics terms.

Lifting things requires power, there is a formula for work done. Keeping things up does not require power, a chair does not collapse under you when it runs out of battery.

A ‘normal’ wind turbine generates a huge force on its foundations when it operates - that’s why they have to be so heavy. It’s not moving so no work is done.

That force does not care what is opposing it - whether it is fighting the strength of the tower holding up the turbine, or if it’s fighting gravity and a steel cable holding the kite. As long as the forces and their directions cancel out, it’s all the same.

Lastly, waste does not matter, wind power is available for many kilometres vertically.

If a kite is flying 500 meters above ground, it can suddenly access the power a turbine could not.

So if it accesses power that was inaccessible before, it’s a win even if half of it is wasted.

Lastly, none of this discussing has any relevance, only economics matters.

You care about cost of equipment, how long it lasts, how hard it is to repair, how many people are required to operate it and therefore salaries, where can you build it - a system could be 100% efficient but unprofitable.

nywles• 3 years ago

I thought turbines work much better when the blades are big. You can only attach relatively small turbines to the kite compared to using the whole kite.

marcandre• 3 years ago

How heavy would this turbine be? Much energy might be wasted just to keep it floating in the air...

kfarr• 3 years ago

A turbine is a huge magnet that turns right? I think it’s heavy. But maybe a spinning thing could transfer the rotational energy down the line and the turbine can be ground based. I’m sure these people have discussed all of this

adgjlsfhk1• 3 years ago

one simple reason is that if you generate power at the top you need to bring it down which means you have a giant high power cable attached to the kite. presumably this makes testing more dangerous because you really don't want that cable to crash into anything.

fransje26• 3 years ago

There are plenty of reasons:

- costs 1): You would need a very different kite to have a turbine hanging in the air. Possibly rigid. They work with a flexible kite, that is possibly much closer to already existing high-performance kites/paragliding wings

- costs 2): You will need a much more expensive tether, as you now need to bring down the electricity that you've produced up in the air, while still being able to reliably and safely reel in your kite

- costs 3): Something happens in flight during testing, or maybe in production, and the kite comes crashing down. There goes your expensive turbine.

- power efficiency: Why would a turbine be necessarily be more power efficient? Action is reaction, so if you are going to remove a certain amount of energy from the air and your kite is stationary, you're going to have to produce a counter-force to stay in place. So how much of the potential energy are you actually using for power generation? Less than half, perhaps? So maybe the pump cycles of a dynamic kite are not that bad after all.

Just some thoughts.

hamandcheese• 3 years ago

After the tether reaches its maximum length, the ground station winches the kite back in. Though the Hawk must expend energy for reel-in, it expends only a fraction of the energy

work=force*distance, so presumably the kite can be controlled such that it exerts less force when they reel it back in?

smileysteve4• 3 years ago

That's my thought from kite boarding, releasing tension on the trailing edge will depower the kite to stall speed

bimguy• 3 years ago

Oddly there is no mention of being safer to flying animals like bats for example, which have their sonar wigged out by the turbines.

I assume the kite would be friendlier to our flying friends but I guess this is not a concern in every country.

Flying kites deliver container-sized power generation

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