Harnessing high altitude wind power
September 18, 2008 at 2:11 pm #697
One of the most important requirements on a seastead will be power generation, preferably through renewables rather than imported fossil fuel based generators. A prime candidate will be wind power. Winds are steadier and stronger at higher altitudes ( http://en.wikipedia.org/wiki/Wind_power#Distribution_of_wind_speed).
There seem to be various companies and people engaged in trying to harness high altitude wind power using various technologies. ( http://peswiki.com/index.php/Directory:High_Altitude_Wind_Power)
One firm which seems to have a ready product is skysails ( http://www.skysails.info ) While their product is meant to help ships save fuel costs and not generate electricity, a simple modification should enable their system to be adapted for power generation. We can try to make some estimates using the numbers available on their website.
My suggestion is as follows : The kite is allowed to gain altitude and, pulling on its tether, generate power. When the kite reaches its highest possible point, the control pod or a simple retro-fitted mechanism such as a second string changes the angle of the kite relative to the wind/ or its surface area and the kite is pulled back down to a certain altitude, consuming a smallamount of power in the process. The angle of attack is restored and the cycle repeated.
Some numbers may be obtained from these documents : http://www.skysails.info/fileadmin/user_upload/Pressedownload/Dokumente/EN_Technology_Information.pdf (see especially page 15 for performance figures) and http://www.skysails.info/fileadmin/user_upload/Pressedownload/Dokumente/EN_Turn_Wind_into_Profit.pdf for costs.
The smallest size is about 160 sqm, and generates 8 tons of force at the following conditions : ship speed 5.1 m/s, wind speed 12.8 m/s, true wind direction 130 degrees. This, the company claims is able to offset about 600 kW of engine power, and using 0.6 as ideal engine output/useful work ratio, means a power generation of about 360 kW. Alternatively, 8 tons of force and ship speed of 5.1 m/s gives a power output of 8000 kg x 9.8 m/s^2 x 5.1 m/s = about 400 kW which is about the same.
Of course, the power is not continuous, since some energy is lost when the kite is being reeled to a lower altitude.
This system costs 420,000(!!!) euros which seems clearly excessive to me. Perhaps a simpler home-made system will be cheaper?
Other points :1) The vertical and the perpendicular-to-ship-direction components are lost when pulling a ship. We can recover these components.
2) Power is limited by ship speed. At low speeds power generation will be low. Since we can let the kite ascend at any desired rate we could optimize this.
3) Some sort of storage will be needed to even out the up and down cycles.
Any thoughts/comments? Maybe someone with experience with kites can shed some light about cost of self made systems, ease of manipulating angle of attack/surface area etc??September 18, 2008 at 3:12 pm #3854
Rather than a sail shape being reeled up and down, make the kite into an autogyro variant. This is much more efficient design because not only is it adapted to the low horizontal speed (perpendicular to the wind flow) you get on a kite at a fixed relative position, not only does it already contain the rotor for driving the generator, not only is it simpler, lighter and maneuverable, but it also uses strictly proven existing technology.September 18, 2008 at 4:22 pm #3855
Google recently invested in something similar. Seems like it could work, and if it did, it would be a welcome solution for a seastead. I doubt we will be able to outdo the people who are working on this fulltime though. If they cant turn it into a marketable product, i dont think we need to bother.September 18, 2008 at 8:16 pm #3857
The problem with experimental power generation is that it´s experimental. So instead of just using tried and tested things (like diesel generators) you need to invent new things, on top of the general seasteading activities. I think we should focus on the core seasteading issues rather than reinventing the wheel on all the infrastructure a seastead will need.
I´m not saying that sails and kites are a bad idea in general, just that at the moment they are not an option, as it is not a proven technology, and there is nothing on the market. If they prove reliable and economical compared to all the other alternatives in the future I´m all for it. Experimenting with things like this once the first seastead is launched is of course an option too. But I´m guessing the power tools and equipment used in these activities will be powered by diesel, and possibly a bit of solar or conventional wind power .
What is wrong with imported fossil fuel, by the way?
A kite will pull the seastead along with it. How do you counter this? Anchor?
A good thing with a kite on a seastead, at least compared to using it on land, is that there is less issue with it falling down on other peoples land if it falls from the sky. You still probably need to make precautions for aviation to avoid accidents.September 19, 2008 at 2:12 am #3859
Point noted about the uncertanity of experimental techniques.
However, in this particular case the basic idea seems so simple and comes with some substantial advantages like harnessing steadier and more powerful winds, without huge towers or blades etc, but with relatively simple fabric kites, a long tether, a storage mechanism (not so simple) and a dynamo that it could be worth considering.
Nothing wrong with importing fossil fuel, just that if an economic case could be made for locally produced energy, we should explore these options. Especially if we want to be truly nomadic/dynamic. It might be easy to get fuel supplies a few miles off California, but what if you fancy being in the middle of the Pacific?
The kite will pull the seastead along. So will a normal wind turbine and even wind acting directly on the seastead, although to a lesser extent. It might be difficult to anchor in very deep water…I was thinking more along the lines of an underwater sail/flap etc to resist the pull as much as possible, then we could draw up the underwater sail and move back to the original location, if that’s really important…it’s not like we’re going to miss the view if we moved a bit though lol
We could use the kite for normal movement too, since that’s what it’s currently used for..September 19, 2008 at 2:15 am #3860
True. It’s called Makani power and they’ve employed a well-known kite expert called Peter Lynn, if I recall correctly. Our circumstances might be slightly different though. They’re aiming to beat coal powered grid electricity, we’re not.September 19, 2008 at 2:21 am #3861
That’s a possibility worth exploring… too bad I’m chained to the desk here. Hopefully if the seastead or baystead takes shape and I come over we can incrementally explore these options. In the meantime I’m wondering whether I can explore this idea myself, small scale.. any really simple suggestions?September 19, 2008 at 2:34 am #3863
We expect that a seastead will use multiple energy sources, with diesel being used when other things are not working out. We do not want to depend upon energy sources that have not been fully developed. We do want seasteaders to experiment with lots of energy source to enlarge the number of available options.September 19, 2008 at 2:44 am #3864
Seriously, I would start by researching wind power in wikipedia and the library. I still like Savonius Wind Turbine due to its low cost and robustness. I’m sure a properly designed turbine can beat a Savonious, but in terms of cost per KW in an ocean environment, I’m less convinced. None-the-less,I would love to see something that is more efficient (but still reliable) than a Savonious rotor in a seastead environment.September 19, 2008 at 6:52 am #3867
Exactly right. Seasteads themselves are experimental enough. If you add more experimental energy sources on top of that you increase expense, decrease profitibaility, add complexity, and generally reduce the chances of success.
Photovoltaic panels, diesel generators, windmills, and batteries are well-established, widely-available existing sources of electric energy and storage.
I have nothing at all against experimental energy sources, and they might make an interesting research and development projects to do on a Seastead (or on land), but I would recommend doing that after building some seasteads that use conventional, readily available energy sources.September 19, 2008 at 8:14 am #3870
Rotorkites are a popular form of kites (we had one back then) that exist in all sorts of shapes and arrangements. There even is a Savonius turbine power-generating kite to be commercialized by Magenn in the next couple years.
They could save a lot of space and offload some weight from the seasteads. The tradeoff is that they are less robust.September 19, 2008 at 6:20 pm #3872
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