Google Makani – Wind Energy Kites
google.com
google.com
- the wing flies in a circle which is perpendicular to the wind (oriented the same way an ordinary wind turbine would be)
- the tether is up-wind from the wing, so the force from the tether pulls the wing into the wind which generates lift, which is used to propel the wing along the circular path
- the propellers are driven by the circular movement of the wing, and generate electricity
So the tether and the wing generate movement, the movement spins the propellers, and the propellers drive the generator. Except for take-off and positioning, where they are used as motors. Am I understanding this?
I think what they're doing is a milder version of dynamic soaring, which is a popular technique used among RC glider pilots (and some birds).
The speeds attainable are pretty insane, the current RC record is 505 MPH, which in a rather fascinating twist is faster than the fastest POWERED RC aircraft.
This a video that shows a pretty good idea of what it looks like, at compartively slower speeds.
The key thing seems to be having different wind speeds available at different heights so you can do the upwind part through slower moving air.
And finally learned the difference between airspeed vs. groundspeed :D
I think it works more like regular stunt and power kites, just relying on the "trim" of the airfoil to produce lift and thrust (and the tether's pull) to make it go upwards and then "fall" down.
http://www.ted.com/talks/saul_griffith_on_kites_as_the_futur...
The tethered airframe converts wind into high-speed lateral motion, sort of like a sailboat would if it were sailing into the wind. These higher speeds can drive the blades faster than if they were simply pointed at a wind source.
I guess it makes sense if it rotates perpendicular to the wind - like the tip of a rotor blade, to achieve these higher speeds.
Would be curious to understand more of the math/physics behind that. But at least intuitively it makes some sense now.
This isn't "design for the masses," it's just plain broken.
Edit: I don't know why I'm being downvoted, it must be working for some people. Here is a video of me trying to scroll (in Chrome) https://www.youtube.com/watch?v=ulAw0P2geRE
Think of it less like an ordinary web page and more like a slideshow, since that's basically what this is.
This whole fad better die soon!
On the flip side, how often do you hear that Apple's software design is driven by data analysis, and how often do you hear complaints about their designs?
Every time I turn on my MBP.
This implementation especially is incredibly obnoxious.
I saw the comments about iOS, it's no better on Chrome.
Browsing without cookies means tons of things are broken — including things that break other things.
Scrolling pages always look weird for me. Image libraries like lightbox are a special pain in the ass.
What I do is tabbing all the way down so the floating window reorganizes allowing me to send the email.
I know scaling Gmail is a gigantic effort but I don't really understand this part (can anyone enlighten me). Gmail essentially has two core pages, the inbox (or list) and compose and tens of millions of users. If they can't fix the positioning of one compose popup how will the rest of us manage?
A fair disclaimer in my own work I'm not sure how good we are in handling these issues but we do have a lot more UI and UI changes. It just makes me feel hopeless.
The first is what sort of density can you get out of these? How many per acre/hectare? 1? 3? California has a number of wind installations and some of them are pretty dense [1].
The second is what sort of radar signature does this thing have? Probably not a navigation hazard but should be interesting on the weather doppler display.
[1] http://www.jamielaval.com/Images2011/Journal/Tehachapi_windm...
On the other hand, wind isn't uniform enough to really allow this.
Here's another kite related technology that uses this to their advantage, they have built a giant computer controlled power kite that is used to power cargo ships (they claim 50% fuel savings in favorable conditions). They're also prototyping for electrical power generation.
Presumably, if they've got the automation figured out, each unit will just manage itself, launching when wind conditions are favorable.
Additionally you have the tether, a new variable, which is another moving piece, and will also need to be serviced.
I've done some back of the envelope numbers, and without assuming a higher capex (which I'm fairly certain it is), on an recurrent basis, an increase in production doesn't really lead to cheaper $/MWh on an O&M basis.
Standard Turbine Makani
Capacity (MW) 1.5 0.6
Load factor 23% 60%
Production (MWh) 3,022 3,154
Availability 98% 95%[1]
Net Production 2,962 2,996
O&M $/turbine/yr 20,000 20,000[2]
$/MWh/year $6.75 $6.68
[2] O&M can be contracted on a turbine or MW basis. Still, given the "complexity" of Makani, the price of this could be higher than the standard cost.
This is a new technology, and not much info is available e.g. how big can these get, what's the investment cost per MW, what are the potential maintenance issues, how does availability look like, etc. My above argument is an educated guess, but I'd really like to know more about it. I really like the idea and I would like the economics to work out.
Also, using smaller generators means that you've got a higher production volume, which can mean significant cost savings. You're also not dealing with giant bearings, gearboxes, etc. which are expensive to produce.
And if you're taking a kite offline, you might as well replace all the motor-generators at the same time. I assume they'll be designed to easily detach and replace. Then, back at the shop, you can check them out on your test bench, and see which ones can return to service in the spares stock.
I agree that the tether is a big question mark.
I met Don on a return flight from SJC to OGG. He seemed very kind and passionate about the Makani Power project at the time. The idea, as he explained it, originated from plans to build a self powered kite boat [1] that could circumnavigate the world. The "self powered" part interested his friends at Google and they started funding him. He confessed that he had accidentally become an engineer in the process, but his real passion was wind surfing and kite surfing and he was eager to get back to that.
Can't find the NS link, but this provides some more info: http://www.abc.net.au/science/news/enviro/EnviroRepublish_18...
[Edit: add url, fix historical reference.]
Are the rotors that launch the kite the same as the ones that generate the electricity?
Looks like there is an open-source community around energy kites. They're largely focused soft form kites, rather than fast moving rigid wings.
And another rigid wing competitor: http://www.ampyxpower.com/
Now, I understand that this project is supposed to provide greater versatility and efficiency using cheaper materials, but it seems to me (by no means an expert on the subject) that these kites are considerably more prone to damage by their very nature too.
Honest question, is this really solving a problem?
P.S.: this website is absolutely horrible to navigate.
Got any data or a link to a resource that will back this claim up?
The blades themselves are composite, that may have some longevity issues (you typically need to paint carbon fiber to prevent UV degradation every view years), but I don't know, they can last for a long time. Fiberglass boats last 50+ years.
I would imagine the designed lifecycle of a wind turbine is 25+ years, and I also imagine that the bases will last long beyond that. In 50 years we may have to go around and replace the blades on these things, but that's it.
Please don't get me wrong, I'm all in favor of clean energy, I'm genuinely trying to inform myself about the pros and cons of each solution.
I'm all for that, but if you decide to do that you also have to use the same methodology for coal, oil, nuclear, etc. Sorry birds, but I feel like the cost of every bird killed by a wind turbine pales in comparison to what a few mountain top removal coal mines do to an area.
In terms of economic ROI for the corporations owning wind turbines, I think it works out even w/o tax credits. Obviously the tax credits help, but the credits are not generous enough to justify all of this investing on their own. I believe the companies have done the analysis and believe it is profitable.
Collisions with wind turbines account for about one-tenth of one percent of all "unnatural" bird deaths in the United States each year.
http://science.howstuffworks.com/environmental/green-science...
If you want to learn more about wind in general you can cherry pick sections from the recently released Wind Vision[1]. It should be able to answer most anything you'd wonder about.
And thank you for the reference, I will make sure to read through it as soon as I get more time.
There certainly was controversy. An initial study did indicate the lifespan was likely to be 12 years[1], but that was immediately questioned because Scotland already had 16 yo windfarms with no maintenance issues.
That initial study led to additional research, which showed that:
the UK's earliest turbines, built in the 1990s, are still producing three-quarters of their original output after 19 years of operation, nearly twice the amount previously claimed, and will operate effectively up to 25 years. This is comparable to the performance of gas turbines used in power stations.
The study also found that more recent turbines are performing even better than the earliest models, suggesting they could have a longer lifespan.[2]
Also, there's no real controversy about "damage done to forests and birds, as well as noise pollution". There's no damage at all to forests, bird deaths are in the order of 0.1% and noise pollution is what it is: they can be noisy if they are built near you, but there is no mystical "subsonics" or something that some people claim.
[1] http://www.thecourier.co.uk/news/scotland/wind-turbines-life...
[2] http://www3.imperial.ac.uk/newsandeventspggrp/imperialcolleg...
These require a lot of manual maintenance, which is dangerous and expensive due to the nature (and location) of the work.
Additionally (and as a demonstration of just how much stress they come under), while coming under said strain, they've been known to burst into flames https://www.youtube.com/watch?v=C_oFPF6Anwo
As for their lifespan, the government agencies that build them claim 25 years, but there's controversy about this. Searching online will find you conflicting studies, including this one http://www.ref.org.uk/publications/280-analysis-of-wind-farm..., which states
"Analysis of site-specific performance reveals that the average normalised load factor of new UK onshore wind farms at age 1 (the peak year of operation) declined significantly from 2000 to 2011" indicating that they may wear out more on the order of ten years.
Now that was a cursory search but in any case the argument that the wind farms cost so much to maintain that they're nonviable is not new.
Wind turbines aren't exotic tech, but it is a giant turbine that is placed way up on a pole, and fundamentally a turbine will need maintenance, so someone has to go up and do that maintenance, and that's expensive.
Also, the recently-published Wind Vision[1] runs with an expected 20-year lifetime, and starts digging into system reliability specifics on page 70. Wind Vision was a lengthy collaborative process with industry, the labs, and DOE HQ. Good news is that there have been significant reliability gains in the gearboxes, generators, and electrical systems.
[1] http://www.energy.gov/windvision .pdfs are on the right.
I thought all wind turbines were built with brakes now exactly to prevent this and other more spectacular failure modes, like the blades fragmenting. They have a defined operating range, and if the wind isn't in that range the brakes engage and the blades don't move.
PS: For scale wind is on target to hit ~8% of total electricity generation in 2018.
http://en.wikipedia.org/wiki/Cost_of_electricity_by_source
Note, wind has gotten much better over time so 2013 numbers look much better than 2006 numbers.
Germany levelized cost of electricity generation in 2013 (EUR/MWh)
Onshore wind farms 45–107
Coal-fired power plants (brown coal) 38–53
Coal-fired power plant (hard coal) 63–80
Regional Variation in Levelized Costs of New Generation Resources
Conventional Coal Minimum 87.0, Average 95.6, Maximum 114.4
Wind Minimum 71.3, Average 80.3, Maximum 90.3
PS: Granted, these don't seem to account for time value of money but that's often overstated in terms of economic impact. Basically, if you turn 1oz of gold into 2oz of gold for free it's a net gain even if it takes 50 years, time value really just means there might be better uses of your personal money not that something is a net loss.
(The offshore ones are huge and I guess changing the angle can't be done anywhere near fast atm.)
Like everything, I'm sure turbine blade tech will iterate. I recall hearing once that solar panels weren't viable because they didn't last long enough to recoup the energy cost it took to build them. I don't believe this is the case any more though?
So besides the material costs of building and maintaining we may run up against one that isn't fixable as quickly, getting the people to do the work.
But I would like to add this: other power plants have similar complex HR requirements (think nuclear, water).
I don't know where you got the information from, but I can assure you that that is not the case. Wind is extremely sustainable, even if we factor in the carbon footprint of the production and construction of the wind farm.
By comparison, it takes about a pound of coal to produce 1 kWh of electricity, more or less. So a single wind turbine produces the equivalent energy of a MILLION pounds of coal every year! How much does it cost to mine and transport that coal, not to mention the construction and operating costs of the plant?
That said, what problem is this solving? Well, the core solution is converting to wind-based power. The kites are just a cost reduction for the conversion process. They presumably cost less to make than standard towers, and are easier and cheaper to install. They probably have long-term cost/kWh benefits as well.
A rail car carries 120 tons of coal.
A typical 2 GWe thermal plant burns a rail car of coal every ~20 minutes (coal has ~30 MJ/kg, and there are ~1000 kg/ton, so 120100030E6 = 3.6E12 J/rail car, and 2 GWe ~ 4 GWth, which over 1000 seconds = 4E12 J)
So by your figures, a windmill's yearly output is equivalent to a little over an hour's operation of a typical coal-fired plant.
EDIT: 1 kWhr = 3.6 MJ, so a pound of coal produces closer to 10 kWhr than 1 (~20 kWhr thermal => 10 kWhr electric after efficiency correction), but the argument still stands. 9000 changed to 900 below.
Windmills are great, and tech like this that increases load factor, lowers costs and extends their reach into more marginal areas is good, but it'll take almost 900 windmills to replace one coal plant, plus oodles of energy storage for when the wind isn't blowing.
One coal plant, on the other hand, can be replaced by one nuclear plant, or a dozen-odd small nuclear plants of modern, modular, passively-safe design.
People who believe anthropogenic climate change has a very significant chance of ending civilization should be pushing as hard as they possibly can in favour of nuclear power for this reason. If we had invested heavily in nuclear in the 70's and 80's we wouldn't be in this mess now.
Nuclear is not without its costs, of course, but all industrial-scale power sources have costs, and no one is seriously proposing we end industrial civilization, so we need to decide which tradeoffs are acceptable. Solar capacity and wind both have roles to play, but it is very hard to escape a role for nuclear in replacing base-load coal.
US coal production was over a billion tons - 2 trillion pounds.
The wikipedia citation cites this meta analysis for the number:
http://www.soest.hawaii.edu/GG/FACULTY/ITO/GG410/Wind/Kubisz...
I then only looked at the first study from there that I found, linked here:
https://www.google.com/search?q=energy+performance+and+life+...
They estimated the lifetime of the farm they studied, and estimated the maintenance and decommissioning costs. Those estimates are probably going to be reasonable, but they are estimates.
But it is sometimes nice to peer through the wikipedia and see what lies beneath.
But the fact that the first thing you picked relied on estimates for those things tells us nothing at all about the quality of the data, just that estimates were used for something where estimates are always used.
I was not trying to paint it as likely that the other studies would be similar to the one I looked at (I see why my phrasing doesn't necessarily communicate that, but I was simply trying to say that I hadn't done more than look at the 1 study).
Consider this - any energy captured from wind can be stored, at some known percentage of loss due to thermal and other inefficiencies. Heck, wind a spring with it! This is going to be less efficient, but not orders of magnitude so - and it still keeps us on clean and relatively inexpensive wind, as opposed to dirty and increasingly expensive fossil fuels.
The argument that some of the materials used in turbine manufacture presently rely on fossil fuels (e.g., coal used for coking steel) doesn't mean that other options for such processes aren't possible. Though shortages of fuelwood were among the key reasons for switching from fuelwood to coal in the first place in the 1600s-1700s.
Thermal coal is replaceable by conservation, nuclear power, and to some extent wind/solar plus storage, and if I were in charge I'd be pushing to ban new thermal coal development. But metallurgical coal is going to be almost physically (or chemically) impossible to replace.
BP's annual energy review 2014 gives total global coal use as 3,881.4 Mtoe (million tons of oil equivalent), which works out to 5.54 billion tonnes of coal. 14% of that is still a large number, 776 million tons.
I happened to look up total forestry production in the US recently, let's see if I can't find that ....
Here: https://plus.google.com/104092656004159577193/posts/NVg1UQ5W...
Total US lumber production is equivalent to 928 Mboe. So, yeah, applying 84% of US timber production to coking activities would supply the world with steel.
(Sources: http://www.loggers.com/timber_facts.htm http://www.fpl.fs.fed.us/documnts/fplrp/fplrp615/fplrp615.pd... http://generatorjoe.net/html/energy.asp )
US steel production is just under 100 megatonnes (2007). Global production is 1,600 megatonnes. So US production is 6.25% of global. The US could provide for its own steel manufacture somewhat more feasibly.
http://www.worldsteel.org/media-centre/press-releases/2014/W... http://www.indexmundi.com/minerals/?country=us&product=raw-s...
Incidentally, energy use in producing construction materials is among the reasons I see a possible future not for biofuels but for biomaterials -- utilizing plants or organic processes to directly provide structural materials (or replacements for them) that we use.
Carbon separation from seawater seems another possible approach, though I haven't specced out that for coking purposes:
https://www.reddit.com/r/dredmorbius/comments/22k71x/us_navy...
The lifespan questions are different -- wind and constant mechanical motion put a lot of stress on turbines and I believe as some other commenters pointed out that the actual lifespans often haven't measured up to the predicted ones.
Makani's capex for a kite should be pretty low; as I recall, talking to Saul like 8 years ago, the difficulty was in stable control of the tethers, not in the economics if control was achieved. But who knows where they're at now (or even exactly how good my recall is).
I live in the land of many wind turbines, the Øresund region of southern sweden, and I know that they can break down or even catch fire from time to time. Who is going to service this aeroplane when it breaks down?
It just seems to me that this idea has too many possible problems that could go horribly wrong from trying to fly a plane around on a teather in strong winds.
To be honest, before I saw the G+ page and read the top HN comments, my first thought was that april 1st is right around the corner. ;)
That said, this is a cool idea.
EDIT: There are quadcopters that can fly inverted, but I think they use powered servos with a reverse polarity. The value of autorotation is that it works when your main power source dies. So it all depends on the context and parameters (is there a backup battery of lower capacity available for emergency situations, say).
That is to say, it has a motor.
This kite will always be doing quite significant movement, so the "apparent wind" on the airfoil surfaces should keep it moving even when the wind is dying down. Additionally, you can reel in the tether to give a little bit of movement to the kite. Typical kites can be flown by walking backwards at a normal walking speed (4-5 m/s or less).
This looks like a very controllable kite, I'm sure their control programs can land it in pretty adverse conditions safely.
http://bangordailynews.com/2014/05/07/news/bangor/umaine-get...
Also, the advanced height they're trying to achieve limits the amount of noise relative to what you would hear from a small drone overhead.
A 300hp hub, spinning a 9ft diameter propeller at 1584 RPM should be roughly 72dB as measured from 1,000 feet. From a mile away, it will be more like 57dB or about TV volume from 6 feet away. -- Then again, these are spinning far faster than you'd expect from a wind turbine.
http://www.bizjournals.com/pacific/blog/morning_call/2014/10...
Makani seems ideal for their needs: "Alaska’s electricity infrastructure differs from that of the lower 48 states in that most consumers are not linked to large interconnected grids through transmission and distribution lines; rural communities in Alaska rely primarily on diesel electric generators for power. " -- http://www.eia.gov/state/?sid=AK
The structure of these "turbines" are that of planes which look like large birds to real birds, so they would stay away from the area with them.
I'd assume that these would be installed in large open fields, so it shouldn't affect migration patterns or bird localities.
I have seen eagles attack quadcopters thinking they were birds, but those are usually of similar sizes to what eagles' prey would look like, but obviously this shouldn't be a problem as well.
http://www.amazon.com/Smiffys-Mens-Borat-Mankini-Dress/dp/B0...
Also, it's interesting that tech companies love using Hawaiian words for things (Wiki, akamai).
They may also spin fast enough to make enough noise to scare birds away, but they are also moving pretty fast, so could pose a problem for birds at the low end of their loop, which is somewhat under 150 m.
Putting them on a migration route would be a very bad thing for birds.