Kites For Future

Basic principle: Energy generation on the ground


View from groundstation flying figure eights


View from the side

A kite that flies figure eights or circles pulls much harder on the line than one that stays steady. This enables us to generate electricity by letting the kite line be reeled out, thus turning the generator. By using the elevators we can steer the kite into gliding against the wind towards the ground station. The line goes loose and is reeled in by the generator/motor with very little power. This reel-out-reel-in operation can be done automatically and continuously for days without landing. In case of a bad weather forecast (hail, snow, sand storm), the kite can land and launch automatically.

60PWh of electricity per year would be the basis to make the world economy in its current size (including all unneccessary comfort) independent from fossil fuels. We are aiming at providing this enormous amount of electricity at a cost of 0.1 ct per kWh with the following device:
Technical Kite Description
How we fly Figure Eights
A large version should generate 1 MW of electricity, or 8GWh per year, meaning about 8 million of them will be needed globally. (The number of globally installed wind turbines in 2019 was just 0.3 % of what's cumulatively neccessary. source)

The special shape of the kite enables flying with very few sensors, as it is designed to be aerodynamically very stable. It orients itself perpendicularly to the line mostly by aerodynamic forces.

Extra strong wing with a carbon fiber reinforced spar inside


Airfoil template for hot wire cutting


The kite


Retired prototypes

2 SENSORS, 3 SERVOS, 2 PROPELLERS
We have designed a custom printed circuit board to hold all neccessary sensors and the autopilot processor.

LIKE A ROWING MACHINE
Pulling the string is hard and produces electricity. When the string is loose, it automatically gets reeled in.




Groundstation power electronics PCBs


STM32 "green pill"



Schematics


Our custom motor controller as seen with an oscilloscope

LESS THAN A CONVENTIONAL WIND TURBINE
For the same electric power produced a kite needs less space on the ground than a conventional wind turbine, because the available power depends on the area covered by the blade of the turbine or the kite wing respectively. As the kite can fly in greater heights the stronger winds higher up can be harvested as well.
Well designed kites can fly synchronously next to and above each other and never touch the ground except at the ground station.

The ground station is far easier to install than a conventional wind turbine, because no leverage force of a tower has to be distributed into the ground. Only an earth anchor is needed. The same is true for floating platforms, as has been demonstrated by Makani.

LOTS
The first flight test with out 2m polystyrene kite yielded 100W of electricity. Flying faster with more wind theoretically (basic aerodynamics) allows up to 5kW with a 2m kite, >100kW with a 10m kite and 1MW with a 30m kite.

But the great advantage over conventional wind turbines is that a small system can also fly in great heights, thus many small kites are just as powerful as one big kite.

We are building wind turbines without the tower. This potentially makes the generated electricity more than 10 times cheaper, even with relatively small systems.

REALLY LONG
Everyone who has tried flying a kite really high as a child knows, kites can be flown with really long lines in the kilometer range.

Copper:
The global neccessary amount of 8 million 1MW kites would roughly need 1 million tons of copper in the generators. That's only 2% of the global yearly copper production!

Steel:
(We estimate that the 23.000 conventional wind turbines built in 2019 used about 5 million tons of steel (200t per wind turbine). The global steel production in 2019 was about 1800 million tons source, thus fully electrifying the world with current wind turbine technology needs roughly 40% of one years global steel production.)
The kites in comparison need hardly any steel.