One of the most interesting uses for drones is often overlooked: producing energy.
Yes, drones can produce energy. So much so that companies like Google, Shell and E.ON bet on drones to become major producers of energy in the not-too-distant future.
How do drones produce energy?
A fully autonomous plane-like drone (like the one pictured above) is attached to a tether and is flown in the wind like a kite:
The drone produces wind energy either with mini-wind turbines mounted on the drone (first picture) or simply by pulling on the tether and turning a generator on the ground (pictures two and three). More details here.
The advantages of such Wind Drones over wind turbines? They can be built with only 10% of the material needed for a wind turbine. More importantly, Wind Drones can reach the much stronger and steadier high-altitude winds that are literally out of reach of wind turbines.
Wind Drones bring the digital revolution to the energy market, the largest market of the world.
The result could not only be a potential "magic solution" (Bill Gates) for our energy and climate problem. The result could be the commercially most important drone application, the "Trillion Dollar Drone".
Most companies in the field of Airborne Wind Energy build rather large prototypes with industry grade components. We at Daidalos Capital were in addition interested in rapid and cheap prototyping and supported University of Bonn in building a mini Wind Drone prototype out of a standard model plane, a Pixhawk and modifed ArduPlane software.
The project was a success and we managed to prove controlled tethered flight with a prototype costing less than USD 1.000 in material costs.
More details on the ArduPlane project will be available soon.
Learn more about Wind Drones and their advantages over wind turbines here: “Producing Energy with … Drones?!”.
Check out kitemill and kitepower.eu as well:)
thanks for the steer on C++ - really appreciated and will follow up.
cheers and good luck!
While the winch based systems with a flywheel seem to be a common test platform, it always seemed like better performance could be gained with a merry-go-round configuration with multiple kites/fliers spooled out on tethers rigged from moment arms on a central wheel unit, sweeping out circles or depressed oval racetrack patterns. Something like KiteGen's Carousel platform design. If individual kites can be controlled via an ardupilot (arduplane-tether?), you might be able to avoid using the 4 tether control rigs of a sport parafoil, and locally control via a control pod closer to the parafoil.
@ Shane: thank you very much!
We ourselves have just started to work with C++: I also did a bit of coding with Fortan 77 long ago and found the book 'accelerated C++' by Koenig and Moo quite useful. So, the first steps were to get accustomed with the concepts of the language and to try to understand the code. It was very useful for us to set up a workspace in eclipse, such that one can more easily follow and understand the structure/program flow: where the system's state is determined, where the navigation takes place. The latter was where we added new flight modes for flying in an inclined circle and eight that are part of the surface of a hemisphere. The SITL environment turned out to be very useful to test the code before doing field tests. It saved us a lot of time.
I hope this info is useful.
Sorry, my mail was far too general. Given arduplane is written in C++, and I have no C++ experience (loads on Fortran77!) I guess the question might be: is the extent of your edits way beyond what someone learning the language might be able to do in say 6 months of evenings and weekends?
Thanks in advance - and I won't divert the thread any more - v nice application.
What you are doing is great. Am v impressed the model flies fine having added tether stress, thats a great result
Sorry to ask a very basic question, but how does one start hacking/editing Arduplane to do this kind of thing? What coding/software experience do you need?
I am at the start with drones, and want to get something flying in 2017 (New Years Resolution) but could not see a path to where I wanted to go (tethered drones but not for energy applications). Am pretty happy with hardware, but my coding experience is more limited, hence my question.
This video showing RC dynamic soaring is a nice practical example of how much energy you can get from wind.
If you paired drones on the same tether with the ground-based "pulley" between them being the generator, you wouldn't have to spool a drum in and out but rather fly one high whilst diving with the opposite, as necessary. It might also offset the cable weight issues.
You are totally right, the dream altitude for Airborne Wind Energy is the jet streams at ~10 km. Above NY, there is over 10 kW median power per m² at that altitude. So 2 m² would be enough to provide the total energy (not just power) consumption of one US citizen, ten wind turbines with today's size could produce as much energy as a nuclear power plant (see here, chapter "World Changing").
The primary limitation of tether length and therefore flight altitude is tether drag. Since the drone is flying cross-wind in circles or figures of 8 the full length of tether has to be dragged behind the drone. For the first generation of Wind Drones, therefore flight altitudes above 300 to 600 meters will not be efficient at most places.
But there is a pretty simple solution to this problem, so called “dancing kites” or “dancing drones”. Two or more drones are mounted on one main base tether that splits into two (or more) tethers with one drone at each end. The drones fly e.g. in circles on the short tethers with the main tether standing basically still. This eliminates tether drag for the single main tether, so that a longer tether become possible from a drag perspective.
Tether strength is not an issue. Today’s materials, e.g. Dyneema, have several hundred km of breaking length, which is easily sufficient.
Tether weight remains an issue, but only insofar as it takes away from the usable power. Given the huge power up there, carrying such a long tether is not a problem.
You can find a description and a video on the jet stream dancing kites here: http://www.antonellocherubini.com/jet-streams-here-we-come.html The paper with the calculations will be published soon.
Currently it sounds crazy, but given the really very attractive potential of going to at least a few km altitude, it is my best guesss that after the first generation of mass produced Wind Drones work (300-600m), the technology will develop very fast to reach at least a few km, maybe even the jet stream. Even for the jet stream version, there are no principle obstacles other than controlling two drones at once, which is not trivial but not that hard either. It is only another control issue, which is what the drone industry is all about.
Here some data on wind speed (grey line) and wind power (blue columns) above London going up to 1500m. The average wind speed there is 20m/s (such winds fall under the category of “Storm”) and wind power is 20 times higher that at 120m altitude (wind turbine) and still 4 times higher than at 500m (first generation Wind Drone).
My understanding is that the higher you go, the more wind potential there is. Found a graph showing the really interesting stuff starting at 2-3km. But then I guess we also get into space elevator territory with regards to tether strength and weight. Any comment on how long the tether can be today before you get into material and weight limitations?