KIDERWIND is an open-source project which aims to harness the wind at high altitude in order to generate power. It is part of the Airborne Wind Energy (or High Altitude Wind Power) technologies which use the kinetic energy of high winds.
This is the motivation for why more than 20 active groups (companies and academic institutions) are currently investigating the new technologies of airborne wind energy. They have to date put a lot of effort into this domain because they know that in the next years the AWE technologies will be able to produce energy in a competitive way in comparison to existing fossil fuel. That's very different from the current renewable energies that are marginal in the global energy market.
The AWE technology does not use a tower but tethered flying systems (like kites or gliders). There are various architectures which can be classified into two groups: fly-gen (the generator is flying) or ground-gen (the generator is on the ground). In our opinion fly-gen systems will be much more expensive than the ground-gen ones because they require a supplementary flying structure in order to sustain the generator and the electric cable weight. Whereas the ground-gen systems are tethered to a motor/generator unit situated on the ground and can be deployed for two kinds of use case, based on:
In both cases the flying system is piloted automatically so that the tether is pulled with a constant strength but at highest velocity to provide maximum return on mechanical power to the ground station.
For more details on how this works see here.
The main advantages of AWE systems are as follows:
The conclusion of this research indicates that through the development of AWE technologies we can meet the worlds energy needs at a competitive cost with a very low environmental impact.
There are some critical issues that should be considered in respect to AWE technologies:
It is therefore important to note that these drawbacks are minimal regarding to the advantages it can bring (i.e all the energy the world needs with a minimal environmental impact).
To estimate the energy production costs using AWE systems we can start from those of fixed tower-mounted plants which are estimated approximately at 70 $/MW h.
As a consequence we can state that with AWE systems the price will be below about 35 $/MW h (for context, consider that 35 $/MW h is the cost of the energy produced by coal based power plants).
It's important that the potential of AWE doesn't remain in the hands of few companies like it is in the case of fossil fuel energy sources. Our proposal is to develop KIDERWIND so that these resources and knowledge can be shared among the global population in a more equitable way, ensuring access to energy to all people. If the costs to build a power plant are lower and at the same time the cost of producing energy is cheaper, access to energy will become more affordable for everyone. A case such as the Arduino (an open-source electronics prototyping platform) shows us that open source hardware allows for the reduction of production costs and consequently enables greater opportunity for many people in being able to buy such products. Furthermore an open-source approach ensures greater availability of the detailed designs and of the know how needed to give people the possibility of building by themselves these power plants. Using Open-source guarantees a system that can be used, studied, redistributed and modified by everyone.
To make this we would like to develop AWE systems using an open-source business model for the hardware part, as well as the software part.
The working mechanics of an AWE installation can be subdivided into three core phases :
Ultimately the tensile force of the sail is converted into energy through a cycle of intermittent traction and recovery.
This cycle (generation / retraction) will be repeated many times until the wind is stronger than the minimum value with which the plant can work (e.g. 3 m/s) and weaker than the maximum value (e.g 20-25 m/s). This phase should last about one minute. In this video you can watch this cycle.
If the wind is too strong or too weak or in the event of potential breakage of the main wire, the glider will try to land as soon as possible on the base station or on an authorized landing area.
Is essentially composed of a winch mechanically linked to an electrical generator and motor.
800-1000m long made with advanced polymers; such as Dineema and Vectra.
Is a combined system that allows the glider to follow a given trajectory (determined by the direction and speed of the wind), so as to maximise energy production but also prevent the tether from breaking. The FCU is mounted at the upper end of the main rope (several hundred meters long) tethered to the ground station. The FCU is also connected to the glider by 4 ropes 10-20m long. The FCU is controlled by an Autopilot (like ArduPilot) which pulls the four ropes in order to optimize the trajectory. Close to the FCU there is a “load cell”which measures the strength applied on the ropes.
An electronic system which forms part of the ground-station designed to monitor the overall performance. The SCU controls the duration of the rising, the descent phases and tracks the energy produced.
The maximum and minimum operational altitudes can be changed at each cycle of operation in order to correlate with the speed of the wind, ensuring the plant works for the longest possible to durations at its maximum power capacity.
Composed of a hybrid system somewhere between a kite and a glider. It will have the advantages of a kite (structural resistance, lightness) combined with the aerodynamic efficiency of a glider. The tensairity technology (see also here for more details) could be considered.
Used for the take-off (and may also be used for the landing).
This phase should validate that the prototype is scalable.
We would welcome collaborations with the following communities to develop the system:
The tether is the most stressed part of an AWE system and it will have to be replaced regularly. The fatigue strength of a rope subjected only to tensile (or traction) mainly depends on the force with which it is pulled. The parameter that allows us to predict the duration of the ropes is the tensile strength expressed as a percentage with respect to the breaking force. In the case of ropes subjected simultaneously to bending and tensile, fatigue strength is significantly reduced compared to the case of tensile stress only. The data provided by the companies that produce and sell ropes allow us to predict that they may have a duration of several months. A compromise should be found between production and maintenance costs. If you want to increase the lifespan of the tether you will have higher production costs but will lower the maintenance costs.