Flying kites deliver container-sized power generation

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.

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.

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

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.

> 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!

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..

> 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.

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.

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

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

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

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).

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.

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.

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.

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

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

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.

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.

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.

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

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.

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

> 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.

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

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.

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.

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

> 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 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.

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

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.

All of the raising is done by the wind.

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.

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

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.

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

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...

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

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?

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

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.

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.

Stalling is more controllable than diving

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.

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

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.

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.

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.

> 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 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.

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.

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

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