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.
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.
That's a turbine in the middle of active farmfield, off a dirt road, servicing a town a bit under a mile away that is barely 10 city blocks wide at its widest point. In the middle of Iowa.
My point just because you can build the turbines to clear everything, there are areas in this nation where there's just no point to doing that; and it's more economical to just make them shorter and put the money towards something more useful
OK, I think I agree but I was responding to london. The idea that wind turbines and large-scale corn cultivation are incompatible is contrary to an abundance of counterexamples.
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.
> 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.
Odd shapes and constantly starting/stopping the plougher/seeder/harvester mean you get less ROI on your equipment. Farming is super tight margins - if your machines waste 20% of the time starting and stopping every time they pass over a road, your farms profits are wiped out.
This is true whether the machines are robot driven or not, and it's the reason most commercial farms have huuuuuge fields rather than lots of small ones.
Why would the access roads create a complex shape? Fields already have access roads. Either the farm is flat and the turbine access roads can be on a minimally invasive grid or the turbines are on a hill and the fields are already a complex shape.
I have trouble imagining that the cost of interrupting your seeder or lifting your plough every quarter mile is really higher than the profit generated by the wind turbines.
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.
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.
>Of course it doesn't. We don't build nuclear generators with pre-approved unusable exclusions zones. This is a ridiculous suggestion.
I'm not suggesting we assign 5,000km^2 to each individual nuclear plant, just in case they explode. I'm suggesting the 5,000km^2 that currently exists as barren nuclear wasteland should be included in the total land attributed to nuclear energy. That would bring down the average generated energy per km^2 pretty significantly.
The dataset does what I've suggested for hydroelectric. The dams are relatively tiny (and in fact, would outperform both wind and nuclear in this dataset), but they render huge areas unusable. The unusable collateral land is attributed to hydroelectric power, as it should be.
It stands to reason that collateral damage caused by nuclear should be included, if collateral damage by hydroelectric is too.
At least we can put lots of nuclear plants in that 5,000 km^2 area so that definition becomes irrelevant for this discussion. Maybe putting the absolute maximum power generated if we turn all available lands to that purpose only is the best metric
It appears it's not far from the truth. According to https://www.britannica.com/story/nuclear-exclusion-zones it's 4100 sq.km. for Chernobyl and 371 sq.km. for Fukushima (800 sq.km. at peak) which isn't an exaggeration. Interesting.
I see. You weren't saying the size was exaggerated. You were saying that the unusable land was being exaggeratedly described as "barren nuclear wasteland". It's unusable land, so it is nuclear wasteland, but it isn't barren AFAIK.
> Should we consider the potential blast radius of the catastrophic failure of wind turbines as well?
Please? (Not as policy, just, like, in general.)
I imagine falling over and/or yeeting a blade-tip is about the worst thing they're going to do, right? I've know they can burn, but I don't think they explode. What's literally the worst that could happen?
There are nuclear plants that have been decommissioned and have not exploded. So using just this data, there is a probability that a given nuclear plant will melt down in its lifecycle. And that probability is greater than 0, but far less than 1.
Yes but wind turbines can’t melt down in that way. Even in a worst case scenario the literal blast radius is smaller. This has to factor in to the possible locations.
> 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!
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?
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.
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.
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.
> I think they saw Google's decision to defund Makani as a sign that kite power wasn't viable
I am very disillusioned with VCs in general.
They aren’t as clever as they make out to be - they have herd mentality, they allow themselves to be bamboozeled and sometimes they outright don’t do their homework and invest in Theranos
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.
Maybe just the ones living under the crane while it's lifting stuff over them.
That also assumes people are living under the kites.
I think you're overthinking a short demo video and hats. I doubt anyone fought hard against wearing it, and company liability is different from your own personal risk assessment.
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.
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.
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.
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?
- 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.
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.
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.
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
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.
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.
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.
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.
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...
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.
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.
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.
Batteries are fine, the majority of the time it'll be in the pull stage as once depowered (the power is taken out of the kite by releasing the brake lines) you can bring the kite back down pretty quickly. Having two with the cycles staggered would reduce this but you need batteries anyway because you can't rely on demand being flat.
The algorithms to control the kite are pretty straightforward, the complexity to self launch would be a bit tough but it's easy enough for a human to do so there is no need to include that complexity for the use cases this is targeting. This wouldn't be a set and forget solution, not yet.
The kites will wear out relatively quickly but they're cheap to replace.
I consider myself a pretty skeptical / practical Engineer and I don't see any show stoppers, I think it'll fit the niche they're targeting quite nicely.
From both a maintenance, operational cost and engineering complexity point of view I don't see this as viable, but I'm more than happy to be proven wrong by a party that brings it successfully to market. Meanwhile, any place where this kite system would work is one where a regular HAT would work as well and long term (25 year lifespan) total cost of ownership and $/KWh generated will be pretty easy to determine by deploying two systems side-by-side.
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.
> 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.
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.
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.
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.
The same kind that makes you immune to crashing a car, none. However the training presumably could help you asses and mitigate risks better than someone with no training.
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!
> 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.
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
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.
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.
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.
Don't take the hard maths approach when you can take the lazy AI approach... Just fly a kite by hand, log the data, stick it through a reinforcement learning system to make you a controller that keeps the kite in the air.
Reinforcement learning loves these kind of problems that only have double digit numbers of scalar inputs and outputs.
Either way, my kite flying experience tells me that your reel-motors must move with quite some speed and power if you are to keep the kite in the air when the wind suddenly reverses direction.
I wonder if it would work better if there was a swarm of kites - or at least several deployed in the same area. Far enough from each other to avoid interference, but close enough so they could share data about the air movement.
I agree with the sentiment that going at it from first principles sounds like a nightmare; teaching-by-example AI approach seems like a faster path to success.
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?
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!
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.
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.
Helicopters do get attacked, not so common because of several factors like the size, flight behavior, altitude, and most importantly the engine size and placement, these birds from my observation they usually attack from behind and/or above, both are properly “protected” in the helicopters, not so much in this kite, additionally, when the pilot is flying, they usually avoid it and continue their path, the birds mostly won’t chase and lose interest, but this kite is stationary and if the bird decided that it is hostile, it will keep trying to prey on it especially when you can’t increase the altitude substantially like a normal drone.
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
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.
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.
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?
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?
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...
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.
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?
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.
I never saw that in the Army, but maybe I was in the wrong kind of unit. I wouldn't count on good continuity between statements of the upper officer corps (political appointees) and the operational realities of the line of business personnel. Just like any big organization.
Yeah I see this as making a lot of sense for armies as a first customer. Highly mobile, reliable energy supply you can set up anywhere (assuming their claims are correct)
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.
> 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?
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.
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.
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?
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.
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.
It wasn’t an ADS-B, Transport Canada (the FAA equivalent in Canada) doesn’t like ADS-B on drones yet, so the solution was to have an SDR (BladeRF, full-duplex for Tx/Rx), the on-board SBC had a server the received the voice sample (either direct through ground station MIC or automated reading directions, alt, etc every X period of time) and then broadcasting it to the airband, so it’s simply:
Ground station mic -> internet -> server on SBC -> SDR -> airband (AM, I think it was ~120Mhz that time) -> other pilots
If you have the manual communication (where the drone pilot comms and not an automated broadcast), you can pretty much talk with pilots as if you are on-board.
I had a better write up if interested on how it works in here, in the “SDR” section.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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
Exactly, that's why calling this concept nonsense is so weird. It might be a tiny bit counterintuitive at first glance, but there's plenty of examples of it all around.
> 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?
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.
> 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