WO2010106382A2 - Un-tethered autonomous flying wind power plant and its ground-station - Google Patents

Un-tethered autonomous flying wind power plant and its ground-station Download PDF

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Publication number
WO2010106382A2
WO2010106382A2 PCT/HU2010/000028 HU2010000028W WO2010106382A2 WO 2010106382 A2 WO2010106382 A2 WO 2010106382A2 HU 2010000028 W HU2010000028 W HU 2010000028W WO 2010106382 A2 WO2010106382 A2 WO 2010106382A2
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energy
wind
power plant
characterized
wind power
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PCT/HU2010/000028
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French (fr)
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WO2010106382A3 (en
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Gabor Dobos
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Gabor Dobos
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Priority to HU0900155A priority patent/HU227468B1/en
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Publication of WO2010106382A3 publication Critical patent/WO2010106382A3/en

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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D5/00Other wind motors
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03DWIND MOTORS
    • F03D9/00Adaptations of wind motors for special use; Combinations of wind motors with apparatus driven thereby; Wind motors specially adapted for installation in particular locations
    • F03D9/10Combinations of wind motors with apparatus storing energy
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05BINDEXING SCHEME RELATING TO MACHINES OR ENGINES OTHER THAN NON-POSITIVE-DISPLACEMENT MACHINES OR ENGINES, TO WIND MOTORS, TO NON-POSITIVE DISPLACEMENT PUMPS, AND TO GENERATING COMBUSTION PRODUCTS OF HIGH PRESSURE OR HIGH VELOCITY
    • F05B2240/00Components
    • F05B2240/90Mounting on supporting structures or systems
    • F05B2240/92Mounting on supporting structures or systems on an airborne structure
    • F05B2240/921Mounting on supporting structures or systems on an airborne structure kept aloft due to aerodynamic effects
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00Energy generation through renewable energy sources
    • Y02E10/70Wind energy
    • Y02E10/72Wind turbines with rotation axis in wind direction

Abstract

The present invention relates to a wind power plant, which is an un-tethered autonomous flying device. This device, according to need, temporarily stores the energy harnessed from the wind, and later on forwards it to a receiver ground-station for further arbitrary usage. Like sailing birds, the invention applies the wind-gradients and updrafts for energy-production by means of dynamic soaring, - instead of static wind. The energy is temporarily stored in the form of liquid air. The liquid-air containers are made of flexible, double-walled plastic foil, and can be forwarded to the ground station by means of remote controlled or GPS-Guided Parafoils. The containers are discharged and folded on the ground, preparing them for the next use. A large number of such devices can be stored on a flying unit. This way a lot of energy can be produced by every takeoff, since the flying unit does not need to take the energy-storing medium (air) with itself, and the payload is only slightly limited. The invention gets around the limitations of conventional windpower plants, as well as that of the high altitude types of devices, and allows as of yet unattainable possibilities in windpower utilisation.

Description

Un-tethered autonomous flying wind power plant and its ground-station

Subject of the invention

Subject of the invention is an untethered, autonomous, flying wind power plant, and its receiver ground-station, just as a method for the operation of these, that -during the floating or moving of the wind power plant in the air-, on the one hand, transforms the mechanical energy of the surrounding wind into mechanical, electric, chemical, etc. energy, and stores it temporarily, then transfers it to the receiver ground-station, on the other hand, the flying wind power plant covers the energy demand of it's own moving/floating from wind energy. The invention can be applied for harnessing of wind energy.

Background of invention

With the decrease of the fuel fossil resources, and, with their depletion in _the foreseeable future, the renewable energy resources are coming more and more to the front. Wind power plants are being built all over the world, to capitalize on wind energy. Most of these are rotor-tools placed on a high (wind) tower: wind-wheels (wind turbine, rotor, propeller - we use these words as synonyms, with the lack of a uniform terminology), that drive electric generators. Such an assembly is called a wind-generator. The power of these devices vary greatly; the range is wide, from ..family" power plants with a few hundred watts (pi.: DE 10 2004 012 603 A1 Offenlegungsschrift) up to complete industrial wind- farms, consisting of many units, that have a capacity of several hundred kilowatts per unit (Wind Energy Comes of Age by Paul Gipe, John Wiley & Sons, lnc New York (1995)) . However, all of them have at least one big disadvantage: they are able to produce energy only when the wind blows. This banality may not appear serious, but it is so much so, that this fact hinders the installation of new wind power plants in a lot of countries (Demand Response For Power System Reliability: FAQ. Prepared for the Office of Electricity Delivery and Energy Reliability Transmission Reliability Program U.S. Department of Energy. Principal Author Brendan Kirby, December 2006. Prepared by OAK RIDGE NATIONAL LABORATORY, Oak Ridge, Tennessee 37831-6070 for the U.S. DEPARTMENT OF ENERGY under contract DEAC05-00OR22725). The thing is, that energy demand is also present in wind-free weather. These demands can be satisfied only by parallelly existing, traditional power stations that have almost the same power as the wind power plants. Over the additional costs of investment, the problem is that a spare power station cannot be turned on like a light bulb when the wind quits. The heating up of a spare power station has a significant time and energy demand. The situation is not better, even when the spare power station always remains preheated, .ready for starting". The additional energy demand is momentous in both cases, which makes the cheap and clean wind energy more expensive, and even ..contaminates" it. Thus, the allowable part of wind energy in the energy production of a country is being restricted by the here described, so called system regulation inflexibility of the electric network. The reassuring solution of the problem would be energy storage with a high degree of efficiency that could be realized in a great order of magnitude and a cheap way. In accordance with the present level of mechanic arts, the parallel maintenance of a pumping-storing water power plant system could be a technically proper solution. However, when we add the costs of this to the investment costs of a wind power plant, then πcheap" wind energy is anything but cheap, and it shall be also considered, that for this, advantageous geological and topographical conditions are needed.

There is a search for the solution of this problem on more lines. One of the most hopeful ideas is the harnessing of high altitude winds. As it is well-known, the Earth is warmed up by sun-rays in the ambience of the equator the most, and in the ambience of the poles the less. The main wind systems of the Earth are created by the temperature difference arising this way. As the Sun always shines, these winds always blow. Naturally, the speed, direction and permanency of winds depend on the geographical position of the concerned area. On the score of the details of this, we refer to the literature (e.g.: Andre Berger: Monsoon and general circulation system. Chinese Science Bulletin Science in China Press, co-published with Springer-Veriag GmbH 1001-6538 (Print) 1861-9541 (Online) Volume 54, Number 7 / April, 2009). Nevertheless, generally it can be stated, that -except a few, well-known and well-determinable calm belts- in most parts of the Earth, constant winds are blowing at several thousand meters altitude, that are stronger than the aboveground ones.

Because of these great heights, it is not easy to extract the energy of these winds. It is not possible to build wind towers thousands of meters high. The tallest building presently is the Burj Dubai, 828 meters ("Dubai opens world's tallest building". Dubai: USA Today. January 2, 2010. , Retrieved 4 January 2010.).

Thus, a lot of patents apply tethered flying devices that float, capitalizing on the buoyancy of winds, and the produced electric energy is transferred to a receiver ground-station through an electric wire, that is parallelly connected to a tethering cable. Several versions of this idea are well-known, for example there are devices that look similar to traditional kites (BP 489,139 US 4,572,962), tethered sailplanes (US 4,659,940 , JP 11124095 , JP 2024295, EP 0 391 601 A2), constructions that are lighter than air (CN1800638), paragliders (NL1015028C) and tethered wind power plants that work based on the principle of helicopters or autogiros (US 7,109,598 B2, US2003/006615 A1). There are also solutions where the wind energy is transferred to the electric generator placed in the receiver ground-station through a mechanical transmission cable (A. Bolonkin : Utilization of Wind Energy at High Altitude. Presented in International Energy Conversion Engineering Conference at Providence., Rl, Aug.16-19. 2004. AIAA-2004-5705. USA.).

Nevertheless, the high altitude winds are much more stable and strong than the aboveground ones, but though the above mentioned experiments are hopeful, these devices have not spread as of yet. The reason of this probably lies with the tethering cable itself, because

1. A several thousand meters long cable can hardly be signified to airplane pilots, which causes risk of a disaster. Thus, such wind farms can be established only in areas that are restricted from aviation ( B.W. Roberts, K. Caldeira and coworkers: .Harnessing High Altitude Wind Power" in: IEEE Transactions on Energy

Conversion VoI 22 No. 1. March 2007. )

2. As these are mostly not individual devices, but so called wind farms, it can be considered common that several devices are operating near each other. In lack of proper control of the tethered flying units, the cables may become tangled, making the operation of such wind farms difficult. It is no coincidence that one of the main development directions is the stabilization of the position of the floating units (US 7,183,663 B2)

3. From the aspect of the retrievable power, the tensile strength of the tethering cable is of capital importance. The weight of the several kilometres long cable is a significant part of the total weight of the whole device. A too strong cable gives a needless overweight to the device, but a too weak one may snap. The breaking of the cable may cause the loss of the expensive device, and may also cause an accident. That is why it's important to reduce the drag, and, through this, reduce the pulling force that is caused by friction, is independent from the energy production, and effects the tethering cable (WO 2007/085807 A1 ).

The question is, if the tethering cable causes so many difficulties, be dispensed with it? Does it have any indispensable function that explains its application? Well, there are three main reasons for the tethering of a flying wind power.

1. The tethering cable guarantees to keep the device in position, and may be used to pull it down if necessary. 2. The resistance against wind speed enables energy production. That is assured by the tethering cable that stops the wind from sweeping the device hinders, Namely, the device swept by the wind takes on the speed of the wind and, if there is no difference between the velocity of the wind wheel (turbine) and thes velocity of the surrounding air, then it is insignificant, that the air is in motion related to a ground- based frame of reference, (that is, the wind blows), because from the aspect of the power plant that is moving together with the wind, it is doldrums, as the speed of the ambient air relative to it is zero. That means: there is nothing that could move the wind turbine. 3. The transfer of the produced power and the extracted mechanical energy to the receiver ground-station.

The listed reasons are all real, and, from a professional point of view, they seem to be valid. It is no coincidence, that none of the experienced solutions are able to get rid of them. Thus, let us inspect these reasons thoroughly.

1. The first of the important aims of the tethering of the flying wind power plant is keeping the device in position. However, this can also be guaranteed without a cable. A helicopter can hover. Though an airplane cannot, it can fly at a constant height, or can circle around a point. This, naturally, causes energy consumption, but this is true for those tethered wind generators, the positioning of which is assured not exclusively by tethering cables, but regulated for instance by a GPS system (US 7,183,663 B2 )

So, the question is not whether it is possible to keep the device in the air floating at the requested height without tethering, because the answer to that is definitely yes.

The question is, whether, without the tethering cable, the energy demand of keeping the device in the proper position consumes or even exceeds the energy quantity that could be retrieved from the wind. None of the earlier flying wind power plants give an energetically effective solution to this problem, so the tethering of the machine remains the dominant solution, even if it suffers from the above difficulties. As mentioned before, the basic and incorrect reason of this is

- ^that the velocity component parallel to the ground, at the place of the wind wheel is defined and always considered as the energetically exploitable .wind speed"

(K. H. Mϋller / J. Giber : Erneubare (Alternative) Energien. Theoretische Potentiate, reale Zukunft der Energieversorgung. Shaker Media Aachen, 2007. , p. 37..).

These considerations are consequent from the vocational aspect, and are naturally correct; nevertheless, as it will be presented later, these considerations will lead to a wrong result, because their basis is incorrect. There is also another way.

2. As shortly mentioned above, it is obviously true, that the resistance against the wind enables energy production. The wind wheel spins, and retrieves energy from the wind, because it takes the kinetic energy of the passing air partly over, that is, the kinetic energy and with this, the velocity of the passing air decreases. The difference of the wind speeds in front of and behind (before and after) the wind wheel manifests itself as pressure difference between the two sides of the wind wheel, i. e. as axial force effecting the wind wheel, namely, as a force with an identical effect line as the wind movement .(G P. Corten: Heat Generation by a Windturbine. 14th IEA symposion December 4-5, 2000, NREL, CO, USA ) . To hinder the axial movement of the wind wheel and enable energy production this way, an anti-parallel force of the same magnitude shall be exerted to the wind wheel. In case of a wind wheel fixed to the ground, the frame; in case of a flying wind power plant, the tethering cable guarantees the resistance against the wind power, and enables the harnessing energy from the wind. Essentially, the theoretical / physical basis of any other, familiar wind power plant is similar.

Well, all this is evident for the professionals, and clear even to most of the laymen, nevertheless there are patents, that contradict this physical banality, and so face the impossibility theory of the first kind perpetuum mobile (e.g.: WO 2007/085807 A1)

Let us emphasize, that this not the case with our invention. Hereby we only remark and later we will present that the tethering of the device by a frame or cable is not the only and exclusive possibility for the exertion of resistance against the wind that is needed for energy production.

3. There is no doubt that the transfer of the produced energy to the receiver ground- station is a key question. In case of a flying wind power plant, the plausible method of this is the application of an electric or mechanical transmission cable that connects the power plant to the receiver ground-station. A supporting reason is, that the energy storing devices that are capable to substitute a cable (batteries, electrolyzers, flywheels, supercapacitors, etc.) have a significant weight that is disadvantageous for a flying wind power plant. It will be presented that this approach -even though it seems absolutely obvious- is false and that there is another possibility besides the mechanical or electric cable to transfer the produced energy to the receiver ground station.

Previously, we talked about the known solutions for wind power plants, and their physical bases, including the flying wind power plants, from the aspect of wind power plant experts.

However, this topic has another aspect that stems from the point of view of flying, and deals with how to keep autonomous flying devices in the air in an energetically effective way. This throws new light upon the concerned problems. Before dealing with this, it is important to define what we mean by wind power plant. This has at least two and at most three criteria:

• Harnessing energy from wind • Forwarding the extracted energy to a receiver ground-station or a ground energy system, for using it for other purposes

• If the two above processes do not happen in an exactly synchronized way, then the energy shall be stored temporarily

It has been well-known for a long while, that sailplanes can stay in the air for a very long time and get to high altitudes through the use of updrafts (thermals, orographical updrafts, standing waves, so called Rossby-waves) (lasd pi.: R. E. Dickinson: Planetary Rossby Waves Propagating Vertically Through Week Westerly Wind Wave Guides in J. of the Atmospheric Sciences, November 1968. Vol. 25. p.984-1002.). These technologies are well-known by sailplaners, parachutists, especially by paragliders and hanggliders. Those who practice these sports or similar military and technical applications are trained in this knowledge practically and theoretically, everywhere in the world. This all belongs to the obligatory knowledge of a professional. Nevertheless, this knowledge has not been used before for energy production with a flying wind power plant.

Lately, researchers of NASA have developed such a sensor system and software and placed it on a sailplane model, that can identify the updrafts from afar, approach one after the other automatically, and use their energy to increase the altitude of flying (M.J.Allen : Updraft Model for Development of Autonomous Soarig Uninhabited Air Vehicles in 44th AIAA Aerispace Sci Meeting and Exhibit 9-12 January 2006. Reno, Nevada. AIAA 2006- 1510). Through the passive utilization of the wind energy, such a flying device can reach several times the flying time that it could normally cover from its own energy resources. This means, a sailplane uses the energy of the wind only for the increase of its kinetic and potential energy, but does not store this energy in any other way, for instance as chemical energy in a battery (M.J.Allen : Autonomous Soaring for Improved Endurance of a Small Uninhabited Air Vehicle, in 43th AIAA Aerispace Sci Meeting and Exhibit 10-13 January 2005. Reno, Nevada. AIAA 2005-1025)

A logical next step of these experiments is when it is examined in a feasibility study whether the temporary bad wind conditions, that are inadequate for soaring, can be surmounted through storing the wind energy during the flight in a battery or other way. The aim of this .regenerative soaring" was that the plane shall lift and land with loaded battery, meaning that it shall fly without fuel consumption. But the sailplane does not transfer the stored energy to a receiver ground station for utilization, just covers its own energy demand for flying . (J. P. Barnes : Flight Without Fuel - Regenerative Soaring Feasibility Study SAE 2006-01-2422) Az Thus, this kind of instrument is not a wind power plant.

Another approach of research began with the analysis of the flight of sailing birds. It is remarkable, how, for instance the albatross is able to fly in any wind in any direction while hardly moving their wings, mostly utilizing wind energy for their flight. It is interesting, that they do not need updrafts for this, just wind in a classic sense, or two air masses of different speeds, on the limit of which these birds cyclically glide, and win energy this way (J. P. Barnes : How Flies the Albatross - The Flight mechanics of Dynamic Soaring. SAE Technical Papers No. : 2004-01-3088). In a more exact way, because of friction, the speed of the wind decreases in a monotonous way as the wind approaches the ground; from this reason, a constant wind velocity gradient arises, and the sailing birds utilize this. This ndynamic soaring" learned from the birds is widely used by gliders nowadays, thus, see the literature for details and references (Heuristic control of dynamic soaring Wharington, J. M. Control Conference, 2004. 5th Asian Volume 2, Issue , 20-23 July 2004 Page(s): 714 - 722 Vol.2 Heuristic control of dynamic soaring Wharington, J.M. Control Conference, 2004. 5th Asian Volume 2, Issue , 20-23 July 2004 Page(s): 714 - 722 Vol.2).

The so called Jet streams", stream zones with high velocity, concentrated in a bottleneck constantly provide a possibility for soaring (Rais-Rohani, Mascud : A Feasibility Study of

Dynamic Soaring in the Jet Stream. A Thesis Submitted to the Faculty of Mississippi State University, Mississippi State, Mississippi, USA 1985.)- Their length may be several thousand, their width a few hundred kilometres, their thickness may be a few hundred meters, and they are typically in an altitude of 10.000 meters. The wind always blows in these nwind streams". The wind velocity in them may reach 50-80 m/s, the energy density may be 20 - 100 kW/m2, whilst in their direct ambience the wind speed is substantially less. This fact makes these jet streams expressly suited for energetic applications. Based on the position of the jet streams, it is possible to set up the receiver ground stations even on sea, or on one or more ships that may replace each other. In this case, the receiver ground station shall be essentially a liquid air tanker that may transport its load to a port, after it is full. The containers of the produced liquid air can settle easily, for instance by means of a parachute and a motorboat that belongs to the base ship can simply collect them, based on their GPS signals. But there are no news yet about any flying wind power plants that would utilize the possibility of jet streams.

Dynamic soaring gives a more general possibility to retrieve the kinetic energy of moving air masses, than the methods mentioned above or those that have emerged concerning any energetic application. It can be presented with a very simple physical calculation that even the theoretically worst case, the downdraft can be utilized for lifting. For the physical basis of this, let us refer to the literature (http://www.icarusengineering.com/Calcs-on- Soaring-Sink.htm).

In the case of a flying wind power plant, the temporary storage of retrieved energy is a critical question. The patent No. US5106035A deals with the liquefaction of the drawn in air and with its storage at the airplane. However, the energy demand of the liquefaction is covered by the onboard fuel and not by the utilization of the kinetic energy of the air.

Above we dealt with two basic wind power plant concepts. However, the flight technology section and the wind power plant section do not really meet each other; that means, the results achieved in the area of soaring are not being applied for wind power plant purposes, rather, the tethering of the devices remains the most widely applied solution. At the same time, the flight experts target only to cover the energy demand of flying from wind energy and not any other kind of utilization of the produced energy or the transfer of it to receiver ground-stations for this purpose. This two-side approach of the problem and the synthesis of the solutions cannot be considered as a range of obvious routine actions.

Summarily, it can be stated that up until now, no wind power plant exists yet, that is based on the energetic utilization of updrafts and wind velocity gradients. No flying power plant is known that is an untethered, autonomous flying device that stores the energy extracted from wind if needed, then forwards it to a receiver ground-station for further, facultative use.

The task to be completed through the invention

The objective of the invention is to provide a solution for harnessing wind energy that enables the energy of winds -especially of high altitude winds- to be extracted, temporarily stored and transferred to a receiver ground station, by an untethered (meaning: not fixed to the ground), autonomous flying device.

Realizations

The task is quite complex, thus, the solution is possible by several separate recognitions that are connected to each other, sometimes even follow from each other.

The first realization, that is the basis of the invention, is that during the harnessing of wind energy, the counter-force -necessary for energy production- against the wind pressure can be satisfied by the weight or inertial mass of an untethered, autonomous flying device.

In the first case, the energy of updrafts can be utilized, and the weight of the device exerts the necessary counter-force against the wind (Newton's fourth law).

In the second case, the principle of dynamic soaring is applied, where the inertial mass of the device exerts the counter-force necessary for energy production. (Newton's second law).

These are those two cases, where the tethering (fixing to the ground) of the device becomes causeless. These solutions do not need any further explanation for aviation professionals, as the application of these is not new for them. The recognition is that this technology can be applied to wind power plant purposes, or made applicable in properly formed technical environment.

From this basic recognition follows the realization that the endeavor to make the flying device as light as possible is incorrect. Namely, the higher the retrievable power, and, parallelly, the wind force exerted against the turbine, the heavier the flying wind power plant has to be in the interest of exerting the necessary force against the wind and thus making harnessing wind energy possible, that is, more intensive in this way. A big power demands a heavy device! The consequence is that -between rational planning limits- no barrier exists to placing storing instruments (for the retrieved wind energy) on the wind power plant, like batteries, electrolyzers, flywheel energy storages, supercapacitors and similar. After these are loaded up, the wind power plant, as an autonomous flying object, lands at the receiver ground-station, empties or replaces the energy storages, then lifts again, and keeps on working. This can be done several times a day, just like an ordinary airplane. In lack of this realization, earlier flying devices targeted only the improvement of their own energy balance through utilization of wind energy, but not industrial energy production, that is, technically speaking, not the operation as a real wind power plant.

With this, we came to a key recognition, that belongs to the essence of the invention, namely, it is not necessary to transfer the produced energy to the ground continuously -for instance by electric or mechanical transmission cable-, but the energy can be transported to the receiver ground station periodically, without any cable, in units depending on the size of the device, further on: in quanta.

In accordance with a further realization, an air liquefaction machine is operated by the rotor of the wind power plant, with which we use the extracted energy for the liquefaction of the drawn in air and store that in this form. The produced liquid air is then transferred to the receiver ground station as described above.

This solution is essentially different from any earlier one. In all earlier cases, the flying device must have been in mechanical contact with the receiver ground station through a cable and all, previously concerned problems must have been considered, or the flying object had to take along with it the energy storage media from the ground, like batteries, supercapacitors, flywheels, or other tools, that took a significant part of the total weight of the device. Though, in accordance with the above points, this can be done, the application of this recognition has momentous advantages. The new recognition makes it possible that essentially only the empty-weight of the flying wind power plant needs to be the takeoff weight, and the energy storing medium -the liquid air- can be collected by it independently, during the flight. Thus, the weight of the produced liquid air does not appear in the takeoff weight, so the takeoff weight can be a mere fraction of the landing weight or of the weight of liquid air produced during a flight period. Resulting from this, the lifting of the device to the target altitude consumes substantially less energy, compared to similar, known devices. At the same time, by operating the rotor during landing, the potential energy of the energy storing material -that is the air collected in high altitudes and liquefied there- can be retrieved, without investing it during the lifting. Thus, this is net energy profit, a kind of ..gift" energy.

The energy, that can be stored through the liquefaction of the air, is approximately 300 - 450 kJ/kg (28); at the same time, the potential energy of a mass of 1 kg in an altitude of 10.000 meters is 98 kJ/kg. So, the above described .gift" energy is everything but neglectable.

This way, we achieve a solution, where in essence a stream of liquid air would flow to the ground from an altitude of 10.000 meters, and (even) the potential energy of it would be utilized, like it would be done the same with water in case of a water power plant. Even though it is true that this liquid air produced at a high altitude comes down to the ground periodically, let us say, in quanta, the analogy is, nevertheless, plausible.

According to a further realization, the liquid air storing unit of a flying wind power plant needs to be constructed as a self-propelling unit (hereafter: ferry), that can be separated from the other parts of the airplane and can be transferred to the receiver ground-station, together with the energy quantum stored in it, without making the landing of the whole device necessary. At the receiver ground-station, the ferry is unloaded, meaning that the produced liquid air is discharged.

The part unit of the ferry guaranteeing its flight can be a .passive" tool, without substantive drive, for instance: parachute, paraglide, sailplane, hang-glider, or self-driving tools, like powered (para)glider, airplane, autogiro, helicopter, or any other -.active" tool, that is capable of flying.

If the ferry is an .active" tool, an empty ferry needs to be sent up to the flying wind power plant, timed so that the empty ferry can replace the other one, that had been filled in the meantime, on the mother unit in due time. With this, the cycle starts again. This realization enables that the ferry include only the liquid air container and the equipments necessary for it's own flight, while the heavy air liquefaction machine can be an integrated part of the flying wind power plant, that remains in the air even after the loading and separation of the ferry.

If the ferry is a .passive" tool, e. g. parachute, paraglider, or remote controllable paraglide (Sherpa Precision Aerial Delivery System [GPS-Guided Parachute] MM1ST 3 lber Road, Ottawa, Ontario K2S 1E6, Canada), then, from such properly folded (collapsed) tools several dozens or even more pieces can be stored on a flying wind power plant. If we store the liquid air itself temporarily in the invented flying wind power plant inside also folded, but inflatable, insulated plastic foil containers with two- three- or multiple walls, then the take-off weight of the device can be very small, as it does not contain the energy storing material; meanwhile, the useful self-weight, that can be separated from the device per quanta and transferred to the ground, is barely limited.

Also an immanent part of the invented device is the receiver ground stations. Besides providing ground service for the flying units, functioning as a complete airport, it also functions as an energy distribution station, assuring the download, temporary storage, distribution and/or further processing of the produced and received energy.

As the invented flying power plant is not tethered, or fixed in any other way to the ground, it is more capable of following the movement and utilize the energy of advantageous atmospheric phenomena, than any other known wind power plant. But, while the flying units are able to follow advantageous atmospheric phenomena for several hundred kilometres, the same cannot be stated about the ferries that transfer the liquid air produced by the flying units to the ground. Thus, it's practical to place receiver ground- stations near to, or even under those atmospheric phenomena (e. g. jet streams), from which the energy is retrieved. But taking into account that these phenomena change their places continuously, this is not easy to accomplish. It has been recognized that this problem can be solved if numerous, much simpler slave stations, that may cover only one function, and are therefore easily affordable, belong to one or perhaps a few central bases, that also include airports (suited to cover all above described functions). Between these two extremes, receiver ground stations can be formed any ways, to fulfill the requested conditions and objectives.

In the simplest case, a slave ground-station can even be a simple liquid air discharging station. The single objective of these plants, which are suitably equipped for this purpose, is to provide landing opportunity and liquid air unloading to the ferries, which are potentially paraglides, equipped with liquid air storage. The extraction may be executed by a parking tank car without needing anything else. Ad absurdum, the ferry may land at a flat land area, field, or water surface. This solution can be employed practically anywhere and after a shorter or longer time of functioning, can eventually be moved to another place, that may be more advantageous. Stations, that can fulfill these functions, are hereafter called energy receiver units.

Naturally, any complementary instruments or devices, that may enable the fulfillment of further tasks, can be optional parts of these energy receiver units. Compared to the minimum-version, for instance one or more optional, liquid air containers may belong to a plant, to which the liquid air can be unloaded from the ferries. The liquid air is to be extracted from the containers to tank cars that come regularly or in case of need, and these transport the liquid air to a better equipped receiver/processing station. Apart from this, one or more optional depots may belong to the plant, for instance to store the received and unloaded ferries.

The essence of the realization is that such a low-budget liquid air extraction system, namely, a system of the above described energy receiver units can make up a network all over the useful area under the jet streams, taking into consideration that these air movements change their places, and how they do it. If we appoint the place or the distance of the energy receiver units from each other properly, then, wherever the jet stream may be at the moment, it is at a favorable location for us, that is, inside the area of our established system. The same applies to any atmospheric phenomena that is utilizable from the aspect of the invention.

These realizations make the application of the tethering cable as well as the application of the cable (wire) that transfers the retrieved energy to the receiver ground station unnecessary. The invented, energy producing flying unit as autonomous, untethered flying device, does not need to be tethered, neither for the reason of reaching/keeping the proper position, not for the reason of transferring the energy to the ground. So, these realizations give a complete solution for the still unsolved problems mentioned during the presentation of the present situation of useful arts, and guarantee numerous advantages over this.

As experienced, the energy storage in the form of liquid air has got a lot of advantages. It was recognized, that the liquid air produced this way, that is cheap and is at hand in a great quantity, opens through the application of superconduction technologies such new possibilities for the completion of the present invention, that could not even come into question otherwise, from the reason of the high costs. Thus, it will be possible to apply light-weighted and high-efficient superconducting generators on wind power plants, and, the electric energy produced this way can be stored in superconducting magnetic energy storages. These tools can be used for similar purposes at receiver ground-stations.

The most general exposition of the invention The invention is an untethered, autonomous flying wind power plant, characterized by having one or more untethered, autonomous, energy producing flying units, and one or more receiver ground-stations, logistically connected to the flying units, where each of the flying units include one or more wind turbines, one or more energy converters, as well as one or more energy storing units; among the receiver ground stations, there is at least one so called .base" station, that includes a complete airport, with all necessary, and at least sufficient accessories known by the experts, furthermore at least one of the ground- stations contains one or more energy processing units.

The following method also belongs to the invention: untethered, autonomous, energy producing flying units from a base station, controlled from the ground, and/or by its own computer control- and navigation system, and/or by pilot, searching for the updrafts and/or wind velocity gradients, furthermore, harnessing the energy of these air movements and covering the energy demand of their own flight, a known way in itself, loading up energy storing units with the surplus energy extracted from the wind, then transferring this energy to any of the energy-storing or energy processing ground-stations, that receives, stores, and/or transforms this to any other kind of energy, demanded by the ground energy system, and/or forwards it to the ground energy system and/or to the user, timed in accordance to the demands.

According to the invention, both the un-tethered autonomous energy-producing flying units (in short: flying unit) and the receiver ground station (in short: ground station) are integral parts of the solution. These two separate parts are not in physical contact in the course of the energy production, but their collaboration according to a fixed timetable ensure the realization of the invention.

In the chapter of "Background of the invention" we wrote about flying windgenerators, tethered to the ground, but these equipments have no unit for storing the produced energy, since it is forwarded to the ground continuously by means of an electric or mechanical cable transmission system. Thus, the production and forwarding of the energy proceeds synchronously. Moreover, there already exists a plane (or rather conception) that harnesses energy from the wind, but this energy is used only to supply the energy of its own flight, because there is no ground station capable of taking over the produced energy, and converting it for other optional use.

The flying unit according to the present invention first sets in motion during the flight its energy converter by means of its wind turbine, driven by the wind. This way, it converts the energy into a storable form, and stores it in the onboard energy storing units. After the energy storing units are filled to capacity, the flying unit ensures the forwarding of the energy to the ground. To this end, it either lands and passes the energy directly to the receiver ground station, or detaches the energy storing unit, and forwards It to the ground staion by means of a parachute or other means. The ground station takes over the produced energy, and sees to its further treatment. According to need, it temporarily stores the energy, then forwards it to the user(s) either in unchanged or converted form. This way is especially suitable to overcome the system regulatory inflexibility of the surface energetic system, - unlike the known wind power plants, which introduce a steady stress to the energy system as a result of the fluctuations of the wind. Opposed to this, the storing of energy as liquid air is the central idea of the invention, which means that there could always be great reserves of liquid air available at the ground-station. Since this liquid air is the fuel of the thermal power plant, the opportunity is given to let it work as needed. Therefore, it can function as a peak-load power plant.

Advantageous solutions

Unlike the known wind power plants, an immanent part of the present invention is the storing of energy. In this respect, it is a serious problem that the energy storing units of a flying wind power plant can never be large enough. This problem is smoothed away almost without any compromise by at least one of the energy storing units being detachable from the flying unit, furthermore, at least one of the surface receiver ground stations having one or more energy receiver units that are capable of receiving the detachable energy storing units.

Advantageously, there is a detachable- rebuildable connection between the detachable energy storing unit and the flying unit.

In the background of the invention, we mentioned that there are flying devices, e,g, paraglider that are capable of delivering their load to the target area without any outside intervention. Advantageously, the detachable energy storing unit is also constructed as an autonomous, self-propelling "ferry", capable of reaching the target area by its homing device. The ferry having a parachute or paragliger, a motor- driven paraglider, a glider, an airplane, a hang-glider, a motorglider, an autogiro or helicopter, makes it possible to change the energy storing units in the air, multiplying the energy storing capacity of the flying unit. If the energy storing unit is filled, it simply has to detach from the flying unit and put in its place an empty one, ensuring the seamless continuation of harnessing energy.

Meanwhile, the full ferry reaches the receiver ground station on its own, where it is discharged. If the ferry is a passive device without its own drive (e.g. a parachute), then after discharging it must be prepared for the next use, e.g. by folding it up. If the ferry is an active device, having an its own drive, then it can return on its own to the flying unit, empty. This process has to be timed in such a way that it has to reach the flying unit in time to undertake the place of the former ferry, which became full during that time.

The unique advantage of the wind power plant according to the invention in respect to all other and known ones is that it can find and follow the atmospherical phenomena required for it to function. The full utilization of this advantage become possible, as a result of there being one or more energy processing- and/or energy receiver units possessed by some receiver ground stations, so-called .slave" stations, which are spatially separated from the base station, but are logistically connected to it.

In the spirit of minimizing the costs, the form of these slave stations can be modest. According to the "minimal version", a flat ground or water surface of the slave station, that is suited to the reception of the landing detachable energy storing units is sufficient. In this simplest case, the slave stations fulfill the part of an energy receiver unit. Their simplicity and inexpensiveness make it possible to cover large regions with a network of slave stations. Since the distance between adjacent stations can be as much as 10 - 50 kilometers, not a large number of such stations is needed.

The detachable energy storing units are advantageously equipped with a signaling/positioning device. This makes it possible to find and gather the ferries, or for the ferry to reach the target area without any external help, by means of autoguidance

In another case, the ferry is equipped with a remote controlling device that enables the remote control of the flight of the ferry, and/or the remote control of the docking and/or separation of it to/from the flying unit. Under remote controlling device, we mean all the equipments making it possible or easier for the ferry to reach the target. To this end the ferry may be equipped e.g. with a positioning system (GPS), or a camera, helping the docking to the flying unit, or the landing.

The same is valid for the flying unit itself. Advantageously, it is also equipped with a positioning device and a remote controlling device, that enables the remote control of the motion of the flying unit (e.g. takeoff and landing), and in a given case the remote controlling of the docking and/or separation of the ferry.

One of the central ideas of the invention is the temporary storing of the extracted energy in the form of liquid air. Therefore, the flying units contain one or more air liquefaction machines, connected to the wind turbine directly or indirectly, and one or more liquid air containers. That is, according to the invention, air liquefaction machine(s) has to be set in motion with this energy, letting the produced liquid air be the energy storing medium.

Advantageously, the liquid air containers are made of flexible plastic foil and function as energy storing units. This makes it possible for the flying unit to take with it several.dozens or even more pieces of the folded liquid air containers. This way, the producible energy amount pro takeoff may be much more then the quantity that could be stored on the plane in the usual case.

Heat isolation is a crucial point in storing liquid air. To this end the liquid air containers are advantageously made of plastic foil and are multiple walled.

This way, the mechanical and formal stability of the plastic foil container(s), can be secured at the same time by gas blown between the container walls. Since air is at hand, in the simplest case the gas applied to blow up the liquid air containers is air. In order to enhance the heat insulating capability of the containers and lower the amount of lost liquid air, the gas applied to blow up the liquid air containers, has to possess a smaller heat conductivity than air. There are known a number of such gases, and some of them is applied to similar pourposes, e.g. in the glass industry, in order to fill heat isolating glasses.

The produced liquid air can be used for numerous pourposes. The priority of the present invention is energetics, therefore, in an advantageous embodiment at least one of the receiver ground-stations includes a heat power plant, applying liquid air and/or liquid nitrogen and/or liquid oxygen as fuel. Some further embodiments apply one or more electromagnetic-rotor machine or superconducting electromagnetic-rotor machine connected to the wind turbine(s) directly or indirectly. Producing electric energy this way, there is an opportunity to apply superconducting magnetic energy storages and/or supercapacitors.

One of the basic realizations of the invention is that the energy transfer between the flying unit and the receiver ground-station proceeds periodically by detachment and forwarding of energy storing units., in discrete doses, so called quanta. This way, the compulsion to forward the produced energy to the ground station immediately comes to an end. But at the same time emerges the need to store the energy. A formerly treated possibility is storing the energy, harnessed from wind, in the form of liquid air in energy storing units placed on the flying units.

Since the wind turbine moves in rotary motion, it is evident to store the energy, harnessed from wind, in the form of mechanical energy, in energy storing units placed on the flying units. Flywheel type energy storing devices are capable to take over rotary motion directly. By the development of the chemistry of composite materials and nanotechnology, the enhancement of their capacity and their further coming into general use is expected.

The production of large quantities of liquid air makes it possible to apply the superconducting technology commercially. Today, there are already known so called high temperature superconductors, working at the temperature of liquid air or nitrogen. This makes storing the energy, harnessed from wind, in the form of magnetic energy, or electrostatic energy in energy storing units placed on the flying units possible. This solution is especially advantageous, if direct current is needed. It is a fast and effective way of storing energy, with the technology looking forward to further development

Another way of storing direct current electricity produced by wind energy is in the form of chemical energy, in energy storing units placed on the flying units. Up to date accumulator technology (e.g. Li-accus) is developing rapidly, although it is a slower device then the former.

The above handled, specific energy storing solutions characterize the diversity of the application possibilities of the invention. But, expectably, the energy retrieved from wind shall be rather stored in the form of liquid air in the energy storing units placed on the flying units. The advantages of this are being specified in details in the description. Examples

Example 1

A remote controlled, motor glider, driven by air turbine engine (self-weight m = 300 kg) is equipped with an air liquefaction machine as energy transformer, and it's fuel tanks are suitable for storage of liquid air. The plane drives its air turbine engine with the liquid air taken along, as fuel. The energy demand for lifting up to a jet stream in an altitude of 10.000 m is E=m*g*H ~ 350*9,81*10000 = 34,3 * 103 kJ, that is equal to 100 kg of liquid air. Moving by dynamic soaring in the jet stream, the plane produces energy by driving the propeller by the headwind. Through driving the air liquefaction machine by the energy retrieved from wind, the device produces liquid air, and stores that practically in the fuel tanks after take-off. Through the production of approximately 400 kg liquid air, the plane reaches the expected weight, and begins to sink, then it lands at the receiver ground- station by sailing. During sinking, the device produces further, around 40 kg liquid air, in accordance with it's total weight of 700 kg (together with the 400 kg produced liquid air), by using it's potential energy of approx 68,7 * 103 kJ. From the produced total liquid air quantity of 440 kg, 340 kg shall be extracted at the receiver ground station, so, the machine is ready for a new take-off.

Example 2 The body of the motor-sailplane according to example 1 is formed as a cylindrical cargo hold, with an openable (collapsible) door at the rear. To ease further actions, the ground of the cargo hold is attended with a line of rollers. In the cargo hold, next to each other, there are placed more, collapsed, double-walled liquid air containers made of plastic foil, inflatable by gas blown between the container walls, attended with parachutes. When the device reaches the target altitude, the air liquefaction starts. Then, an automated instrument blows up the plastic container nearest to the cargo hold door; the puffed container takes a cylindrical form, and flexibly fills the free space between the cargo hold door and the other, collapsed containers. The device collects the produced liquid air into this container. When the first container is full, the automat blows up the second one, that, during taking the cylindrical form, pushes the first container towards the cargo hold door gradually; thus, this latter one opens the cargo hold door in the meantime. When the second container takes it's final form, pushes the first one out of the airplane; the headwind helps that, too. First, that parachute leaves the plane, that is placed at the rear of the container; and the headwind opens it. The opened parachute pulls the container out of the plane, and lands with the load. Then, the plane loads up with liquid air the collapsed containers taken along, the above described manner and gets them one after the other to the ground station. Hereby the mission of the plane is over. Lastly it fills it's fixed liquid air container, that functions as a fuel tank, and lands with full tank at the receiver ground station. There, the cargo hold shall be reloaded with plastic foil containers including parachutes, and the plane is ready for a new mission.

Example 3

It is the same as example 2, with the difference, that the liquid air containers made of plastic foil shall be attended with remote controllable paraglides and GPS devices. So, the parachute containers leaving the airplane can be navigated by remote control exactly to the receiver ground-station, where they can be treated promptly: the liquid air can be discharged, the container and the parachute can be re-collapsed (re-puckered), and prepared for loading another empty airplane with them, that is waiting at the receiver ground station

Example 4

It is the same as example 3, with the difference, that the flying units shall compose a fleet consisting of 4 sailplanes, that guarantee the quasi-continuous energy provision of a receiver ground station. Thus, each of the planes shall land in every 24 hours, meanwhile, the receiver ground station receives a plane in every 6 hours, that spends 2 hours on the ground. During this time, the plane shall be prepared for a new take-off by necessary technical checks and smaller reparations, and by reloading it with empty, collapsed liquid air containers made of foil, that are attended with parachutes. If take-off, and reaching the target altitude take 1 hour per diem for a plane, and sink-sailing takes another hour, 20 hours remain for energy production. In this time, the device may load a foil container of 200 litre volume with around 170 kg liquid air in each hour. So, each of the planes produce 3400 kg liquid air with one take-off; the 4 planes produce 13.600 kg, that is equal to approximately 1550 kWh.

Example 5

A sailplane with m = 300 kg self-weight is driven by an electromagnetic-rotor machine, that is able to operate both in engine and generator operation mode. The energy provision is guaranteed by a battery weighing 400 kg. The battery shall be of a type, that has a great storing capacity, practically, for instance a lithium-polymer-electrolytic one, that can store around 80 kWh electric energy with the given weight. The energy demand to lift up to a jet stream in an altitude of 10.000 m is E=m*g*H - 700*9,81*10000 = 69 * 103 kJ = 19,1 kWh, that agrees 24 % of the capacity of the board battery. The sailplane shall load up the approx 76 % free battery capacity by utilizing the wind energy. For this, it produces energy with it's electromagnetic-rotor machine operated in generator mode, whilst DS-ing in the jet stream, having the propellers driven by headwind. After the complete loading of the battery, the plane sails down to the receiver ground station, where the battery shall be partially rendered, say, the produced energy shall be discharged, or the battery shall be simply replaced, so, the cycle can restart.

Example 6 It is the same as example 5, with the difference, that the onboard energy storing shall be realized by superconducting magnetic energy storage.

Example 7

The above examples explain some aspects of the receiver ground station's role in the reception of the retrieved wind energy. Thus, the energy has arrived to the ground, mainly as liquid air, that also solves the temporary storage of energy at the same time. (The examples concerning other forms of energy present, that the invention is also capable to satisfy special energetic demands). Depending on the demands, the receiver ground station may forward the stored liquid air to the end user in the same form, or processes it locally. One of the obvious processing methods is, to generate high-pressure compressed air by vaporizing liquid gas, that drives an electric generator through a gas engine. The electric energy received this way shall be fed into the ground electric network, scheduled according to the demand.

Example 8

Beside the base receiver station(s), the slave stations have an important role, that receive in the most simple case the ferries, that transfer the liquid air to the ground, and extract their contents. The maximum, respectively practical distance of these energy receiver units from each other are determined by the glide ratio of the ferry, the height of the jet stream from the ground, furthermore, by the prevailing winds and wind speed. If, for instance, the jet stream is in an altitude of H = 10 000 m, and the glide ratio of the ferry is S = 10, then the ferry is able to perform a distance of H * S = L = 100 km with it's load from the location of the energy exploitation. That means, the receiver ground-station or extraction station shall be located inside a circle with a radius of L = 100 km from this place. The centre of the circle shall be proofed with the local wind data, as this coincides with the place of energy exploitation only under windless circumstances. Truly, the affected area is not circular, but, if we calculate with a proper security allowance, and handle with proper prudence during determining the location of energy receiver units, there will be no dead space in our system, and, wherever there will be advantageous winds in the system created this way, we will be able to retrieve energy.

With this solution, we will be able to utilize the whole area, that can come into question from energetic aspect, without leaving obtrusive clues on the ground. All visible clues shall be embodied in small, above specified energy receiver units, located 20 - 100 km from each other, and a thermal power station with zero harmful material emission, operated with liquid air fuel (or that's derivatives, like for instance liquid nitrogen or oxygen), that may process the products of near extraction plants. Such power stations could be built 50-1000 kilometres far from each other, practically with a distance of 50-200-300 km, depending on wind facilities. This means, by the allocation of the power plants, seasonal and other motions, respectively energy content of atmospheric phenomena used for energy production (e. g. jet streams) shall be taken into account.

This system suits well into the concept of liquid nitrogen economy, that is yet a futuristic concept, where the energy storage and transport shall be realized through liquid nitrogen (30).

Example 9

This example presents the operation of wind power plants included to the invention, respectively a few possible modes of this. To operate wind power plants included to the invention is a more complex task, than the operation of ground or tethered ones, because the autonomous flying units shall find the dynamic wind conditions, that are necessary for the operation (updrafts, wind velocity gradients), and shall utilize these recurrently, a πdynamic way". This belongs to the mandatory knowledge of aviation professionals. Thus, in the most simple case, the flying units shall be controlled directly by pilots. Their work shall be supported also by weather reports, that they receive through telecommunication channels. A part of these data is already public today, and is available for example on the Internet. Useful arts enable it already for the pilot not to seat really in the flying unit of the wind power plant, but to be in a ground office, and look at the aviation and operation data of the flying wind power plant on a display. So, eventually, a pilot can drive one or more flying units by remote control, meanwhile his/her own weight does not load the flying unit, in place of that, it is possible to put technical equipments or more energy container units into it. Through using a proper software, the entire system can be controlled by computers, too (as presented during the analysis of useful arts), so, the ,,pilot" has tasks similar to an airport tower crew. Thus, at last, he/she coordinates the operation of the whole system.

Advantages of the invention

Summarily, according to the invention the energy of each moving airstream is exploitable for production of energy, and keeping the flying unit aloft, the speed of which differs from the speed of the adjacent air masses. The invention utilizes not the wind speed itself, but the gradients of it, or the updrafts for harnessing energy from the wind. Hereupon the present invention differs from all of the known wind power plants.

The new features of the present invention are obvious, since the wind power plant according to our new concept and the former ones are mutually unable to work in circumstances, favourable to the other. This fact sharply distinguishes the two types of wind power plants. A wind turbine installed on a conventional wind tower is unable to harness the energy of updrafts in its surroundings, and it is obviously unable to seek and find them. For a tethered flying wind generator, it is pronouncedly dangerous to reach the shearing zone of two air masses moving with significantly different speeds. On the contrary, these are the most favourable circumstances of operation for the wind power plant according to the present invention

So, the present invention is based on some up to now unutilised possibilities in wind energetics, and getting around the limitations of the conventional wind power plants, as well as that of the high altitude types of devices, opening up formerly unattainable possibilities in wind power utilization.

In the chapter background of the invention11 we have already mentioned the jet streams. In these .wind rivers" the wind blows steadily. The wind speed is usually/typically about 50-80 m/s, and in accordance with it, the energy density is about 20-100 kW/m2 In the direct vicinity of the jet stream, the wind speed is significantly lower. This fact makes the jet streams distinctly suitable for harnessing the wind energy according to the present invention, seeing as from the great energy density follows the small size of devices. A conventional wind power plant with a standard rotor diameter of 48 m (e.g. Mecser, Hungary) is equivalent with a flying unit according to the present invention having a rotor diameter of 1,5 m.

At the present time, human intervention into the processes of nature is a great problem. Global warming is already an indisputable fact. Experts are of the opinion, that the cause of this is the emission of greenhouse gases, which is the express consequence of human activity. But not much mention is made of another fact, namely that the energy demand of mankind in our days is statring to become a significant part in the energy balance of the Earth, especially considering the exponential nature of its growth. In the year 2005, the quantity of the absorbed solar energy by the Earth in proportion to the consumed energy by mankind was 11.290 : 1; that of all the winds blowing on the Earth was 228 : 1, while this proportion regarding to the whole quantity of the biomass was only 11 : 1. ( Eurec. Agency/Eurosolar, WIP: Power for the World - A Common Concept) Seeing these relations, it might be obvious in perspective, but maybe even nowadays, that burning fossil fuels and releasing their long-ago inhibited energy, that had not been part of the energy circulation of the planet for eons, into the energy balance of the Earth after millions of years, bears a great significance. However, the situation is not better in the case of nuclear or fusional energy either, though the latter is the hope of all of us since it should be capable of producing endless quantities of clear energy from almost nothing. Well, the trouble is exactly the ..endless" quantity and from ..nothing". If we do not pay attention, we can .bake" the Earth without greenhouse gases too! Seeing this trend, maybe it is near the last moment, when we have to make the correct decision: if we feel warm, (and we feel it more and more) then we must not think about buying a new stove (fusion power plant), but shutting off the heating.

To do so, one of the possibilities is the utilization of wind energy. But knowing the limitations of current designs, one can see that this is a totally unreal intention. . (K.H. Mϋller / J. Giber : Erneubare (Alternative) Energien. Theoretische Potentiate, reale Zukunft der Energieversorgung. Shaker Media Aachen, 2007. , p 39. ) That is, wind energy industry needs new ideas. The present invention is more than an attempt; it is a complete system on this topic.

Hereupon we would like to point out that the energy balance of the solution according to the invention is zero. Applying the liquid air as energy storing medium, not only does the medium itself get back to the environment after usage, but the energy too. In order to liquefy the air, we extract energy from the environment (wind), and using this energy, we lower the internal energy of the air, and deprive it of the latent heat. But at the same time, this energy will be dissipated into the environment by means of a heat-exchanger. Exactly the opposite process proceeds by warming up the liquid and expanding it. This way, by applying a gas engine we get work at the expense of ambient heat. When this work finally degrades into heat, the thermal balance of the local system is zero. The machines are running, but no waste heat is produced at the point where the energy is used! The cycle is closed, and the energy balance is zero. (Cesare Marchetti: Transport and Storage of Energy. Presented at the Third Conference of the European Physical Society, Bucharest, September 9-12, 1975.) This way we do not heat the Earth. This solution agrees with the strictest environment-friendly demands, as well as with the requirements of sustainable development, since all the energy (including that needed for its own work) is extracted from the wind, and the storing of the energy also proceeds without any chemical substance, accumulator etc.

As already mentioned, the known wind power plants introduce a steady stress to the energy system as a result of the fluctuations of the wind. Opposed to this, the storing of energy as liquid air is the central idea of the invention, which means that there could be always great reserves of liquid air available at the ground-station. Since this liquid air can be the fuel of the thermal power plant, the opportunity is given to let it work as needed. Therefore it can function as a peak-load power plant.

Like liquid air can be the fuel of a thermal power plant, so can it be used as a fuel in the propulsion of vehicles. To tell the truth, a larger tank is necessary because of the smaller energy content of the cryogenic fuels when compared to fossil fuels. (About 300 I as opposed to the 50 I of fossil fuel tanks for cars.) There are already working solutions using liquid nitrogen, called LN2, manufactured from liquid air. The above mentioned benefits can be made use of in a complex system, namely in urban traffic technology. In this case, the smaller energy content of the cryogenic fuel is not a serious problem. Applying a kinetic energy recovery system (KERS), the energy demand can be significantly lowered by recovering the energy of the frequent braking. Today, everything is ready for this technology to be utilized; only cheap cryogenic fuel available in large amounts(liquid air rather than liquid nitrogen) is missing. Should this proposal be put into operation, the pollution due to the urban traffic could be eliminated.

There is the opportunity to realize the driving of a generator or gas engine in such a way, that in the course of warming and expanding the liquid air to execute its fractional distillation, it is driving the machine and at the same time produces oxygen, nitrogen, argon and other gases from the processed air. Selling these products decreases the price of the produced energy or liquid air/nitrogen, respectively. At last, the wind power plant, according to the present invention, does not violate the interest of the landowners, since the ground station is not fixed to the wind. And further, it does not violate the aesthetic sense of those people who say that the wind power plants disfigure the area. It is easy to manage the problem of the noise pollution because we have sufficient freedom in choosing the place of the ground station.

Claims

Claims :
1. Untethered, autonomous flying wind power plant, characterized by having one or more untethered, autonomous, energy producing flying units, and one or more receiver ground-stations, logistically connected to the flying units, where each of the flying units include one or more wind turbines, one or more energy converters, as well as one or more energy storing units; among the receiver ground stations, there is at least one so called -base" station, that includes a complete airport, with all necessary, and at least sufficient accessories known by the experts, furthermore at least one of the ground-stations contains one or more energy processing units.
2. Wind power plant according to claim 1 , characterized by at least one of the energy storing units being detachable frqm the flying unit, furthermore, at least one of the surface receiver ground stations having one or more energy receiver units that are capable of receiving the detachable energy storing units.
3. Wind power plant according to claim 2, characterized by a detachable- rebuildable connection between the detachable energy storing unit and the flying unit.
4. Wind power plant according to claim 2., characterized by its detachable energy storing unit, that is constructed as an autonomous, self-propelling Jerry „ , also capable of reaching the target area by its homing device.
5. Wind power plant according to claim 4, characterized by the ferry that has a parachute or paragliger, a motor- driven paraglider, a glider, an airplane, a hang- glider, a motorglider, an autogiro or helicopter.
6. Flying wind power plant according to claim 1 or 2., characterized by one or more energy processing- and/or energy receiver units possessed by some receiver ground stations, called .slave" stations, which are spatially separated from the base station, but are logistically connected to it.
7. Wind power plant according to claim 6, characterized by a flat ground or water surface of the slave station, that is suited for the reception of the landing detachable energy storing units.
8. Wind power plant according to claim 2, characterized by the detachable energy storing unit, that is equipped with a signal/positioning device.
9. Wind power plant according to claim 4, characterized by the ferry equipped with a remote controlling device, that enables the remote control of the flight of the ferry, and/or the remote control of the docking and/or separation of it to/from the flying unit.
10. Wind power plant according to claim 1, characterized by the flying unit, equipped with a positioning device.
11. Wind power plant according to claim 1, characterized by the flying unit, that is equipped with a remote controlling device, that enables the remote control of the motion of the flying unit.
12. Wind power plant according to claims 4 and 11, characterized by the remote controlling device of the flying unit, that enables the docking and/or separation of the ferry.
13. Wind power plant according to claim 1 or 2, characterized by the air liquefaction machine, that is connected to the wind turbine directly or indirectly, and one or more liquid air containers
14. Wind power plant according to claim 13, characterized by the liquid air containers) that is(are) made of flexible plastic foil and function(s) as (an) energy storing unit(s).
15. Wind power plant according to claim 14, characterized by its multiple walled liquid air containers made of plastic foil.
16. Wind power plant according to claim 15, characterized by mechanical and formal stability of the plastic foil container(s), that shall be secured by gas blown between the container walls.
17. Wind power plant according to claim 16, characterized by the gas, applied to blow up the liquid air containers is air.
18. Wind power plant according to claim 16, characterized by the gas applied to blow up the liquid air containers, having a smaller heat conductivity than air.
19. Wind power plant according to claim 1 , characterized by at least one of the receiver ground-stations, which includes a heat power plant, applying liquid air and/or liquid nitrogen and/or liquid oxygen as fuel.
20. Wind power plant according to claim 1, characterized by having one or more electromagnetic-rotor machine, connected to the wind turbine(s) directly or indirectly.
21. Wind power plant according to claim 1, characterized by having one or more superconducting electromagnetic-rotor machine, connected to the wind turbine(s) directly or indirectly.
22. Wind power plant according to claim 1, characterized by having one or more superconducting magnetic energy storage and/or supercapacitor.
23. Method for the operation of untethered, autonomous, wind power plant, characterized by the taking off of untethered, autonomous, energy producing flying units from a base station, controlled from the ground, and/or by its own computer control- and navigation system, and/or by pilot, searching for the updrafts and/or wind velocity gradients, furthermore, harnessing the energy of these air movements and covering the energy demand of their own flight, a known way in itself, loading up energy storing units with the surplus energy extracted from the wind, then transferring this energy to any of the energy-storing or energy processing ground- stations, that receives, stores, and/or transforms this to any other kind of energy, demanded by the ground energy system, and/or forwards it to the ground energy system and/or to the user, timed in accordance to the demands.
24. Method according to claim 23, characterized by the energy transfer between the flying unit and the receiver ground-station, that proceeds by detachment and forwarding of energy storing units.
25. Method according to any of the claims 23-24, characterized by storing the energy, harnessed from wind, in the form of liquid air, in energy storing units placed on the flying units,
26. Method according to any of the claims 23-24, characterized by storing the energy, harnessed from wind, in the form of mechanical energy, in energy storing units placed on the flying units.
27. Method according to any of the claims 23-24, characterized by storing the energy, harnessed from wind, in the form of magnetic energy, in energy storing units placed on the flying units,
28. Method according to any of the claims 23-24, characterized by storing the energy, harnessed from wind, in the form of electrostatic energy, in energy storing units placed on the flying units,
29. Method according to any of the claims 23-24, characterized by storing the energy, harnessed from wind, in the form of chemical energy, in energy storing units placed on the flying units,
PCT/HU2010/000028 2009-03-16 2010-03-12 Un-tethered autonomous flying wind power plant and its ground-station WO2010106382A2 (en)

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HU0900155A HU227468B1 (en) 2009-03-16 2009-03-16 Flying wind power station

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HU227468B1 (en) 2011-06-28
HU0900155D0 (en) 2009-05-28
WO2010106382A3 (en) 2011-06-03

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