Hello! I work at Makani (https://makanipower.com), which is mentioned in the article:

> Nor is it absolutely necessary that the electricity generation is done on the ground. Makani, a firm recently absorbed by Alphabet, Google’s parent company, has a different approach. It is lifting the generators into the sky, on board a pilotless aircraft with a wingspan of 26 metres. This craft has eight rotors, which act as propellers for take-off and landing. Once at operating altitude, however, they become miniature turbines. The electricity they generate (600 kilowatts at full capacity) is sent to the ground through a power line encased in a tether nearly half a kilometre long. Makani’s prototype has been tested in Hawaii and, later this year, a further series of tests from an oil platform off the coast of Norway are planned.

I'm excited to report that we really did pull off the offshore test a few months after this Economist story went to print.

Video of our recent offshore test: https://www.youtube.com/watch?v=F6NW0QeKLZA (I know it almost looks like a rendering, but it's for real!)

And a company blog entry about the test: https://medium.com/makani-blog/makanis-airborne-wind-power-s...

Makani was funded in part by ARPA-E earlier in its existence, and they recently also made a video about Makani that might be of interest: https://www.youtube.com/watch?v=C9Ly6na58e0

Hi, I work in offshore wind, subsea cabling, and I’m very interested in the cable tether that connects the kite to the base station and how you over come the issues with fatigue in the metallic elements of the cable, seems like this would be an interesting challenge as you try to balance weight / fatigue life / transmission capability.

Lol, these things are big !!! I had the scale all wrong. When I saw the pictures and video I thought this plane was something one or 2 people could hold (6-12 ft wing span). Then I saw people talking about 600kW and I was like, no freaking way can you get that much power from a plane that size.

Then I saw this: https://makanipower.com/makani/images/pages/technology/cta.j...

Compared to a single blade of a wind turbine it looks like a toy.

True, but they fly up where the wind is a lot stronger. Plus being much smaller means they might be cranked out in large numbers by a factory, which would make them relatively inexpensive, and also they don't have the major shipping problems that onshore turbines have.

Will this eventually look like the city power supply in Big Hero Six?

How visible are these things from the ground?

Edit: Ignore the following line. It is too early in the morning.

--A single one is producing 600KW, so you need a few per household, and many thousands for a town.--

The average US residential annual electricity consumption is around 11 MWh or around 30kWh / day (11,000 kWh / 365 days) [1]. Assuming it produces 600kW for 24h or around 14MWh / day, this services around 480 homes (600 kWh * 24h / 30 (kWh / home)).

Their website explicitly says [2] (Overview 1.4):

> designed to transfer up to 600 kilowatts of electrical power—enough to power about 300 homes

[1] https://www.eia.gov/tools/faqs/faq.php?id=97&t=3

[2] https://makanipower.com/

600KW / (1500W / microwave oven) = 400 microwave ovens

See https://en.wikipedia.org/wiki/Kilowatt_hour#Confusion_of_kil...

If you were standing directly under a 36 meter wingspan kite, 500 meters off the ground, it would be about 16 times as wide as the size of the moon.

That's kw hours. A big house running air conditioning is only 6kwh.

kWh is a unit of energy, that is, power over time, kW is a unit of power, that is, instantaneous energy.

Your car engine is rated in power (typically horsepower in the US, though kW is equivalent), your car fuel tank is rated in energy, that is kWh or joules.

Power determines how hard you can work. Energy determines for how long.

A big house running AC for a hour would give you a kWh number. The instantaneous load is measured in kW.

Yeah but if it makes 600kw then it can do it for an hour since it's a generator not a battery

I prefer the method of releasing ions to be carried away by the wind, producing charge separation that can be used to perform work. No-moving-parts windmills should be the future of wind power.

It doesn't need any exotic materials, and it scales up to unlimited size. Stretch a mesh between a pair of tall buildings, or between pylons of old, worn-out windmills, or, yes, across a kite.

Alvin Marks patented a version of it in the 80s.

He didn't say how to make the ions. Some materials spontaneously give up surface electrons to wind, so you might get away with streamers of the stuff tied where warp meets weft, if it is made slightly conductive.

I see such things with a lot of skepticism. Here's why:

With varying intensity I've been following renewable energy development for many years. I've seen many proposals for new forms of wind energy, many of them looking promising. Same for new forms of solar, new forms of water power and many other things. The Kite approach isn't new either.

However the reality is that the only thing that's been successful for wind energy is to do almost the same thing they've been doing in the past, just bigger, better and cheaper. The biggest efficiency win in wind energy is to build similar technology, just with bigger wings and larger towers. The biggest innovation was to bring costs down. Technology got better in the details, the basic "three blades that spin around" stayed the same.

I know this is pretty boring. But it's successful. I'd bet on "make wind energy cheaper and larger" more than on any fancy new tech.

I feel that way with a lot of tech, the best way to upgrade is to make it larger and reduce costs. But we still gotta try other approaches on the off chance they work, don't we? Without that don't we lose on innovation?

I could be biased because I do not want to live in a world where we're mainly making incremental updates, but it seems like that's what it is.

The other factor being "put the bigger, cheaper turbines closer to where the wind is blowing".

That has driven offshore wind farms, kite turbines, and placement patterns such that turbines can be placed more closely together without stealing wind from each other.

Unpaywalled: https://outline.com/uPXtNv

I hope something comes out of this one. Kitegen has been around 2006 and nothing to show for it.

A few years ago a similar story about similar technology popped up, and I referred [1] to a New Scientist story[2] from 2000 that described something remarkably similar, being designed and built by an Australian researcher called Bryan Roberts.

[1] https://news.ycombinator.com/item?id=9222149

[2] https://www.newscientist.com/article/mg16722574-800-reach-fo...

Here's a video explaining it, from the same company: https://youtu.be/3VKFJ2_cQmM?t=147

I wonder why none of the projects is trying balloons... Or are they?

Mass vs. lift.

For the stated generation model, the kite's lift is being directly used to create electricity as it is reeled out and in. For lofted generators (Google's power kites), you're putting the turbines and generators in the air. Both are more effective with kites than balloons, as in the first you get more lift providing generation directly, and in the second a far smaller wing can support a much larger weight than is possible with a balloon.

Frankly I don't think any of these approaches is very practical in the long term at scale. Too many fiddly bits.

Wind is a second-order force. It’s even worse than solar - hard to believe!

I'm not sure what you mean exactly, but I think 2nd order force is a fair description. Except you diss solar, so I'm a little confused.

To me, solar is first-order. Solar leads to wind, so it's second-order. (Though really, solar heats water and air, producing wind, so it's kinda third-order.) Oil is... uh... the sun grows the plants which die and get compacted, then we pump up the remnants. I'm not sure what you'd call that.

Uranium is, like, zeroth order then. Fusion in the Sun produces solar.

And yet, none of this really means much. Unless you're constructing Dyson spheres, it really doesn't matter how efficiently you're capturing the max theoretical energies. If you don't believe me, stop eating. Try replacing food with sucking on a power cord.

I’m referring to energy density. Because civilization requires ever-increasing amounts of energy to grow and prosper.

Solar, even concentrated desert solar, is no good at all. Wind is a distant derivative and much, much worse.

Hydrocarbons and nuclear are the fuels of today and tomorrow because they are orders of magnitude more energy dense. These energy sources are so dense they double as energy storage.

Come back with your concerns when we fully exploit the potential of wind and solar and run out of energy. Right now covering single digit percentages of the world with solar panels would satisfy our energy needs.

I am concerned now because covering the world in solar panels and wind turbines is unsustainable. Each siting location by definition is worse than the one before. The vast land area required will cause tremendous societal and environmental impact. Problems of energy storage, rotating mass, and baseload power remain unsolved by wind and solar.

We need to get on nuclear. Then we can help poorer nations with nuclear power so they can undergo their own Clean Industrial Revolutions. In 80 years we all want the world’s ~11 billion plus people to live far better than we live in the West today.

If you say:

> Each siting location by definition is worse than the one before.

How is that not true for nuclear power plants? If we have better tech, we can remove old panels and wind turbines. With nuclear plants the place is lost forever. Let alone that there cannot be a safe place to store the waste.

Energy storage and baseload are in fact solved problems: a good grid (because it's always windy somewhere), and a combination of batteries for overnight storage and power-to-gas for long term storage.

I'm in favor of nuclear power too, but it takes too long to build.

> Energy storage and baseload are in fact solved problems: a good grid (because it's always windy somewhere), and a combination of batteries for overnight storage and power-to-gas for long term storage.

That's far from solved, countries close to each other have very similar weather pattern and wind electricity is especially unreliable. We're also very unlikely to have a massive breakthrough in turbines since we're close to the theoretical maximum already.

The talks I heard by the engineers that actually studied this disagree with you.

Here's what a real wind production looks like: https://twitter.com/TristanKamin/status/1153626109814202368, spot the problem.

Wind turbines obey Betz's law https://en.wikipedia.org/wiki/Betz%27s_law and are already close to maximum efficiency, the only thing you can do is drop the production cost.

Now add enough batteries to those charts to store 10h or so of energy and expand the grid to western Europe. Add in some solar as well.

Experts wrote thick reports on how to transition to renewables. You shouldn't dismiss their work with half a dozen graphics on Twitter.

Is the problem that the chart only covers a specific month and does not combine multiple intermittent energy sources into one?

Depending on the region, seasonal differences caused by low wind are canceled out by higher solar production and low solar production is canceled out by higher wind production. That chart completely fails at showing that.

For comparison calculate the percentage of the earth covered with nuclear power plants to reach the same goal.

Available area is really not the problem.

Before or after meltdown irradiates the countryside?

I'm a LFTR fan. Solar wind has won and civilization should concentrate on enabling it to eliminate gas/coal from our energy production.

Take waste disposal into account and hydrocarbons are not dense at all, they change the composition of the entire atmosphere with their emissions.

Solar and Wind are free and widely availabe primary energy sources. No infrastructure is needed to dig it/pump it up, transport it and process it befor it is usable, as with fossile fuels and nuclear power.

One you take into account energy storage, backup and associated supply chain I think benefits are minor at best

Energy density isn't exactly the most important criteria of an energy source.

Nuclear has a higher energy density than hydrocarbons or batteries but we still don't see nuclear powered cars and aircraft everywhere.

Solar has a maximum uniform density of 1kW/m^2, roughly, at Earth's surface.

Wind, though a 2nd-order form of solar energy, concentrates at some points on the surface. Since both forms work by way of building some form of collection capital and recovering energy, wind allows a higher site-specific EROEI than solar, given favourable siting. Not in all locations, but in some.

That's why wind power makes sense.

Though I'm skeptical of airborne / kite-based generation.

Second-order force?

Doubletalk.