DE102012025763B3 - Energy generation with energy storage system and compressor in the wind turbine tower - Google Patents

Abstract

A power generation plant (30) with an energy converter unit (31), which naturally contains energy directly via a compressor (34) in the wind turbine tower for generating compressed gas (G) and a compressed gas tank (35) for receiving and storing the compressed gas, wherein an energy storage system ( 33) is provided, which comprises a torque generator (36) for converting pressure into mechanical kinetic energy, and wherein the torque generator, a power generator (32) is connected downstream, which converts the kinetic energy into electric power and the power grid N supplies, characterized in that the energy conversion unit and the energy storage installation can be operated independently in island operation without connection to the public power grid, that a switching device (37) is provided, with which the power output line (32 ') of the power generator can be separated from the public power grid , If the compressed gas container is located below a water surface W and pressure equalization openings (D) are provided in the compressed gas container, a higher pressure in the compressed gas container, depending on the water level difference (W-W '), can be obtained for a longer time during the removal of compressed gas. As a result, a pressurized gas container with sufficiently large capacity and pressure resistance, as well as with geological and geographical independence can be charged without having to use the standardized power from the public network.

Description

The invention relates to a power generation plant with at least one energy converter unit, which can convert naturally occurring energy such as wind, solar, thermal or water energy directly or indirectly via at least one power generator into electrical power, which via a power output line of the power generator a public Power network is supplied, wherein an energy storage system is provided which comprises a compressor for generating compressed gas, a compressed gas container for receiving and storing the generated compressed gas and a torque generator for converting pressure of the compressed gas into mechanical kinetic energy, and wherein the torque generator downstream of a power generator is that can convert the mechanical kinetic energy of the torque generator into electricity and supply the public power grid.

Similar energy generation plants were presented at the Innovation Day Energy 2007 / Cottbus "Storage Technologies / Adiabatic Compressed Air Power Station" by a consortium for Advanced_Adiabat-Compressed_Air_Energy_Storage AA-CAES.

Energy storage technologies are in great demand because direct electricity storage in larger quantities is hardly feasible. However, the energy consumption is always winding with many distributed maxima and minima. Distinct differences exist in the comparison of day and night needs. Pumping force storage units are so far the compensation technology that can switch between consumption (pump operation) and power generation (generator operation) in no time and thus can bring supply and demand to the same level. Used here is the stored potential energy of a water column in the water tunnel, which is connected to a reservoir. This type of energy storage requires geological and geographical conditions that z. B. are best given in the Alps.

However, with the technical progress of wind turbines or even solar technology, the electrical energy is generated arbitrarily in time and locally in the lowlands or in the offshore wind farm. Of course, usable energy storage are hardly available here and for the transmission of electrical energy you need a transmission line network with large transport capacity, which can also distribute peak loads. But it is precisely the smaller and locally distributed power generation plants that could cover the required peak loads locally, if they could feed stored energy at the right time as electricity into the public grid.

The lecture cited above outlines the operation of a CAES in Huntdorf (here abbreviated: CAES_HT) realized compressed air storage power plant. As a pressurized gas container large-volume caverns are used, with this pressure moves in operation between 50 and 70 bar. The pressure is built up by means of a compressor which is driven by a motor / generator unit (engine operation). For power generation (generator operation) this unit is coupled with the generated torque of a gas turbine, which is operated in addition to the compressed air used with natural gas. It is therefore called for the total analysis only an efficiency of 42%.

Another cited A-CAES plant, Mcintosh, (abbreviated here: CAES_MC) uses the heat generated by the combustion of fossil gas in a turbine through a recuperator (preheating of the compressed air) and thus increases the efficiency to 54%.

Another quoted AA-CAES project funded by the EU (abbreviated to CAES_EU) uses no fossil gases and increases efficiency to 70%.

CAES_HT has a geological and geographic dependence on very large caverns with relatively low operating pressure of 50 to 70 bar, which requires additional fossil gas demand. This requires a gas turbine as a torque generator. It is also disadvantageous that the motor / generator unit is dependent on the standardized public grid (eg fixed voltages and a fixed feed frequency of 50 Hz). Likewise, distributed energy producers could only use the compressed gas tank via the public network. Finally, it should be noted to this variant that the waste heat is not used by the combustion of fossil gas and the compression of the ambient air to increase the pressure in the compressed gas tank.

CAES_MC also has all the enumerated features of the CAES_HT, except for the use of waste heat, for example, by a recuperator, which arises in the gas turbines.

CAES_EU works with a special expansion turbine that does not require additional fossil gas. Otherwise, the mentioned disadvantages are also stable here.

In the patent literature are about Offenlegungsschrift US 4,353,214 proposed three different energy storage systems. All are similar to the A- CAES most likely. In the first two variants, a second larger cavern is used in such a way that the exhaust gas is collected at the turbine outlet, with a compressor drawing precompressed gas from this second cavern on its intake side instead of sucking in ambient air. However, the usefulness of this arrangement can only be limited because, on the one hand, the pressure in this second cavern must not be too great, so that the turbine flow is not obstructed, and on the other hand, a low cavern pressure hardly contributes to an increase in effectiveness in the compression. The decisive cavern is thus the first with the high working pressure of 50 to 70 bar (5 to 7 MN / m ² ). There is a relatively low working pressure, which is why gas-powered turbine systems are used.

In this regard, the three systems differ in the type and production of the supplied fuel gas for a typical gas turbine in the variants non-system reactive gas; produced by electrolysis H ₂ and O ₂ ; endothermic reaction CH ₄ + H ₂ O → CO + 3H ₂ .

In the second proposal, the foreign total supplied fuel gas is replaced which is introduced into the air circulation through the electrowon in the system H ₂ and that in the second Niederdruckkaverne. The resulting O ₂ is stored in a small special container and then fed into the combustion chamber as needed to assist combustion. So there are three separate memory in use. In the two caverns is a vaccinated with H ₂ compressed gas and is compressed as in the first proposal in the first high-pressure cavern.

In the third proposal, the caverns are each filled with different gases and these each have their own mass circulation in the system. In the low-pressure cavern CH ₄ , supplied by the turbine outlet and in the high-pressure cavern, the gas mixture formed by endothermic reaction, consisting of compressed air, CO and H ₂ , which is compressed by the compressor. In the exothermic reaction CO + 3H ₂ → CH ₄ + H ₂ O, the energy-carrying components of the high-pressure cavern are removed and the low-energy CH _{4 of} the low-pressure cavern is supplied without compression.

Characteristic of all three variants are the geographical dependence on existing caverns and their limiting working pressure limitation.

Another publication US 2012/006 1973 A1 deals with the energy storage of an offshore wind farm using open-bottomed air tanks of the same design anchored to the seabed. These openings ensure an isobaric behavior of the compressed air tanks due to the hydrostatic pressure of the acting water column. An offshore platform carries the necessary machinery, such as engine, compressor, turbine and generator. The wind turbines deliver standardized power to the public grid, while the storage platform can remove excess energy from the network to fill the underwater tank with compressed air until the sea water is completely displaced from the compressed air tanks.

Again, there is a local attachment to water retention with considerable depth (10 bar = 112 m water column) and the resulting low and limited working pressure. The further consequence of this is that the storage volume must be greatly increased in order to store significant energies. For example, there are 178 compressed air tanks of dimensions 8 m × 8 m × 8 m = 512 m ³ for storage of 1 MWh for 24 h at a depth of 112 m. However, wind turbines can deliver more energy and a larger wind farm should increase the need for pressurized gas containers n times. Also, the buoyancy forces created by the voluminous volumes are likely to be significant for anchoring to the seabed.

Object of the present invention is in contrast to modify a power generation plant of the type described above with the simplest technical means so that a compressed gas tank can be charged with sufficient capacity and pressure resistance, as well as geological and geographic independence, without the standard power from the public To use network.

This object is achieved by the subject matter of claim 1.

Another mode of operation of the invention can initially be recognized when a power generation plant is in the operating state of energy storage. Here, the power generation plant has separated via the switching device from the public grid and now converts the pending form of energy in the pressure of a gas, which is located in a compressed gas tank.

• a) Wind → Drehmoment → Druck,
• b) Sonne → Gleichstrom → Druck,
• c) Sonne → Wärme → Druck,
• d) Anlagenabwärme → Druck.

In this way, in natural mode, the natural, but arbitrary forms of energy - including electrical energy, which does not meet the standard of the public network - directly and without detour via the standard public grid in pressure energy converted and stored in the compressed gas storage. Examples are:

• a) Wind → torque → Print,
• b) sun → DC → pressure,
• c) sun → warmth → Print,
• d) Waste heat → pressure.

Example of a): In 3 Only one compressor in the tower head delivers compressed air directly to the compressed gas tank. So the wind turbine would only generate pressure energy. A second compressor stage in the tower base can optionally be added if an even higher pressure is required.

Example of b): In the simplest case one could use a DC motor to operate the compressor.

But it is also conceivable and beneficial in certain cases, When the resulting direct current is used for the electrolysis of pure water. The resulting gases, hydrogen and oxygen can be stored in different containers 5 - Stored, or also be compressed, if necessary in the drive pressure vessel 5 To produce enthalpy by an exothermic reaction, which can maintain the pressure in the drive pressure vessel under dosed injection.

Example of c): The existing heat from solar radiation can be transported by means of collectors and fluids in an adiabatic heat storage, in turn, if necessary, the heat can be pumped to increase the pressure in the drive pressure vessel.

Example of d): Similarly, the process waste heat, which occurs in the proposed variants primarily in the compression of gases, can be led into a nearly adiabatic heat storage, which is quite a segment of the container 5 can be.

These examples show that it is very useful to hide the public grid and to store the local energy directly with as little loss as possible. Also, the establishment of an energy park with different energy sources and a central compressed gas tank as in 4 presented, would be very beneficial.

Of course, it may be that the use of certain auxiliary equipment, such as controls, control device or additional high compression makes a supply of standardized parameters of electrical energy to a small extent necessary.

Of very important importance is the design of zughörigen compressed gas tank. Such a container would preferably have a plurality of chambers, which are arranged in a cup shape and, as in 5 illustrated, for the high-pressure operation having an internal chamber, which is used as a drive chamber for the torque converter. The located in the direction of the environment chambers with medium and low pressure have the advantage that only differential pressures occur between the chamber walls, which are structurally easier to control. Another constructive measure is the arch form shown, which has statically special advantages, because here particularly good pressure forces can be absorbed. Also, other forms, such as, for example, paraboloid rotors or hyperboloids of rotation may be considered.

However, the multi-chamber system of the compressed gas storage system can also be used advantageously to store other compressed air other gases, such as the products resulting from the electrolysis products water and oxygen. If necessary, these can then be injected directly into the inner drive pressure chamber and reacted, the resulting enthalpy can increase the pressure directly in the drive pressure chamber, and a low energy loss occurs. If pressure controls are used for the drive pressure chamber, one can even use the dose of the injection as a manipulated variable.

However, the other mode of operation of the invention can also be recognized when a power generation plant is in the operating state of power generation, wherein a generator is coupled via the switching unit for feeding to the public power grid. In this case, compressed gas is passed from the pressurized gas container to a torque converter. Examples are pneumatic or hydraulic motors, cylinder-piston engines or pressure-reducing turbines.

In particular, starting from the conventional construction of a wind turbine according to the current state, two generators would be used. So you would create space in the tower base or in an outbuilding for a compressor and the unit: torque converter / second generator. When switching to storage mode, the compressor would increase the pressure in the compressed gas tank.

The compressor requires an electric drive and possibly also special power electronics, for example, a frequency converter that is able to use the deviating from the norm current of the wind turbine. In this respect, the decoupling of the public power grid is necessary, that is, the power generation plant can thus work independently in island operation. But now you have the considerable advantage that the wind turbine on the highest possible Torque can set without having to pay attention to the 50 Hz standard.

However, an additional object of the invention is to advantageously provide only a single generator. The technical effort, such as space, maintenance and costs is significantly reduced. When constructing new plants, you will therefore prefer this option.

Another variant provides that several identical or different energy converter units, which are provided, for example, according to a) to d) and which are each connected to a central energy storage system. For example, it is possible to combine the energy generated by wind turbines and solar collectors at different locations, which of course are not too far apart from each other, in a common energy storage system and store them there until it seems opportune to feed into the public power grid. Thus, an energy park can be set up and operated in a favorable manner. It is also possible in this form to supplement existing energy production systems by the storage component.

In an alternative class of variants, it is provided that the energy converter unit comprises a wind turbine, that the energy storage system is arranged spatially immediately adjacent to the energy converter unit and that the energy converter unit and the energy storage system form a structural unit with a common structural platform. This compact arrangement has many advantages: Here, the wind turbine tower can also be integrated in a constructive unit.

It is advantageous that the power generator are arranged together with the torque generator in the tower head of the wind turbine and the compressor in the tower base.

In this arrangement, the wind vane can be engaged and disengaged as a torque converter as needed. But it is also conceivable - and a very great advantage of this variant - when both units together turn the generator at low wind. It is also advantageous if the switching unit is designed intelligently, for example, with a speed control for 50 Hz energy, the control difference either on the actuator torque, at too low speed a positive torque is passed, or on the actuator compressor a negative torque at high speed is switched and selectively removes energy to increase the pressure in the compressed gas tank.

The arrangement according to the invention discloses a power generation plant with at least one energy conversion unit that can naturally convert existing energy - such as wind, solar, thermal or water energy - directly or indirectly via at least one power generator into electrical power, which via a power output line of the Power generator is supplied to a public power grid, wherein an energy storage system is provided which comprises a compressor for generating compressed gas, a compressed gas container for receiving and storing the generated compressed gas and a torque generator for converting pressure of the compressed gas into mechanical kinetic energy, and wherein the torque generator a power generator is connected downstream, which can convert the mechanical kinetic energy of the torque generator into electricity and supply it to the public power grid, characterized in that
pressure chambers are arranged in the pressure gas container so that the pressure decreases in stages in the direction of the environment a → b → c,
that the energy converter unit and the energy storage system are designed so that they can operate independently in isolated mode without connection to the public power grid, by electrical energy that does not meet the standard of the public network,
a switching device is provided by means of which the current output line of the current generator can be disconnected from the public power grid,
and that the compressor can be charged directly with energy from the energy converter unit, wherein only a single power generator is provided, the energy storage system is located immediately adjacent to the energy converter unit, and that the energy converter unit and the energy storage system form a structural unit with a common structural platform and wherein the compressor or a supercharger in the tower head of the wind turbine and the power generator are arranged together with the torque generator in the tower base.

A particular advantage of this arrangement according to the invention is that the speed of the wind vane can be arbitrary and no technical effort has to be made to ensure a 50 Hz energy. This object can solve according to the invention the combination torque converter / generator in the base of the tower, with known and common control devices, such as vane position or control valves and corresponding power electronics can be used.

A development of this arrangement is characterized in that the energy storage system by another another Energy converter unit can be supplied with stored electrical energy by switching with the island mode.

A more general development is characterized in that a plurality of identical or different energy converter units are provided which are each connected to a central energy storage system.

Another development of energy storage systems are characterized by the fact that the pressurized gas container is located in a lake or in the sea partially below the water level and in its submerged area has pressure equalization openings for inflow or outflow of water, wherein in the pressure equalization openings water turbines are arranged, which can be driven by penetrating into the pressurized gas container or exiting from this water. This can be similar to how tidal power plants additionally generate electricity.

This variant can thus provide a lot of volume for the compressed gas container. The structural form can be optimally designed for the occurring, lower differential pressures. A further advantage is that in the power generation state water penetrates through the equalization openings and thus the volume is reduced, whereby longer higher pressure can be maintained in the drive container.

Another development of a power generation plant is characterized in that an electrolysis device for splitting water into hydrogen and oxygen is provided, which is operated with power from the energy converter unit, that the compressed gas container has at least three storage chambers, of which the first with hydrogen and the second with Oxygen from the electrolysis device, the third can be charged via the compressor with compressed air, and that additional pressure in the third storage chamber can be generated by increasing the temperature due to a thermal reaction of hydrogen and oxygen from the other two storage chambers. With metered and regulated injection duration can be kept constant in this way, the pressure in the gas cylinder for a long time, which makes compliance with the 50 Hz standard easier.

In this way, with the variants described, many smaller decentralized power generation plants with storage capacity can arise, which, although locally limited, but can ideally be adapted to the variable power requirements, such as a small town.

In larger energy parks, for example offshore installations, it may be the case that the energy generated goes far beyond the requirements of the immediate vicinity. Again, there is a great advantage obvious, because the far away leading power lines, targeted by each energy store can be taken offset in time and thus oversizing of these routes is not necessary.

The advantages of the energy storage system described could also be used to temporarily store energy, for example, for a time-sluggish power plant, in order to not have to accept energy losses in the case of an intended power reduction if the electricity can not be sold.

Another combination could provide significant benefits to a fossil-fueled power plant if it uses low-flammability fuels such as oil shale, oil sands, or waste. The hydrogen and oxygen produced by other energy sources and stored in the compressed gas tank could be used here to start the combustion process, or else to homogenize the combustion in the combustion chambers by locally targeted injection.

Show it:

1 a schematic horizontal sectional view of a power plant with a switchable from "grid feed" to "storage" power generator in the tower head of a wind turbine;

2 a similar, but even more compact version of the power generation plant, in which only a single power generator is needed;

3 Another compact variant of the power generation plant with a tower head of a wind turbine arranged (pre-) compressor and a torque generator with downstream power generator in the tower base;

4 a power plant with multiple energy converter units in different technologies;

5 a schematic vertical cross section of a special compressed gas tank with a plurality of chambers, which is particularly well suited for building an energy storage system;

6 a parameter diagram for the volume requirement as a function of the pressure p ₂ in a pressurized gas container, for an energy of [1 ... 10 MWh] generated in 24 h as a parameter;

7 a parameter diagram for the temperature change T ₂ as a function of the molar volume n ₂ in a compressed gas container with the pressure p ₂ as a parameter; and

8th a parameter diagram for the stored molar volume n _{2, H2O} in a compressed gas container, as a function of the pressure p ₂ and V as a volume parameter.

1 : This is a power generation plant 10 consisting of a conventional tower-shaped wind turbine with energy converter 11 , a generator 12a and the power output line 12a ' to public network N. Furthermore, is an energy storage system 13 shown with the compressed gas tank 15 , which lies partially below the earth B and is filled with compressed gas G. In memory operation, the power output line 12a ' over the switching device 17 disconnected from the mains and to the compressor 14 connected. The compressed gas tank is now charged. In power generation mode, the stored pressurized gas in a torque generator 16 relaxes and torque through an axle to the generator 12b transfer. The generator now supplies the generated power via the power output line 12b ' into the public network.

In this variant, it is possible that a) the generator delivers without storage in the network, b) is only stored without delivering to the grid and c) it is stored and the generator 12b delivers to the network at the same time. Case c) makes sense if the compressor does not supply standard-compliant power from the generator 12a can handle.

2 : It is one of the 1 similar power generation plant 20 in a more compact form, requiring only a single power generator. This advantageously eliminates the components 12b and 12b ' of the 1 ,

The components in the tower head are: energy converters 21 , Generator 22 and the torque generator 26 , The compressor 24 is located in the base of the tower and feeds the compressed gas tank 25 that under the platform 28 arranged energy storage system 23 , The pressurized gas container is designed to be open here and has equalization openings D, in which water turbines can also be located, wherein an incoming and outgoing water drives the turbines. The location of the energy storage system is in the sketched variant in the sea, or in a lake with the earth B. The differential pressure between the water levels W / W 'determines the pressure of the compressed gas G.

In memory operation, the power output line 22 ' over the switching device 27 disconnected from the mains and to the compressor 24 connected. The compressed gas tank 25 will now be charged.

In the power generation operation, the stored pressurized gas G becomes a torque generator 26 relaxes and torque through an axle to the generator 22 transfer. The generator now supplies the generated power via the power output line 22 ' into the public network.

Advantageous in this type of power generation plant 20 is the hybrid drive of the generator 22 through the energy converter 21 and (or) the torque generator 26 , where both can independently engage and disengage.

This combination gets great importance when the switching unit 27 is designed to control the speed of the generator on kontant (50 Hz energy). The compressor can 24 a metered negative torque from the generator 22 split off and the torque generator 26 bring a metered positive torque to the drive axle.

3 : It is one of the 2 similar power generation plant 30 , wherein in the tower head housing only one compressor 34 is used by the energy converter 31 operated without further motor support and the compressed gas tank 35 that under the platform 38 arranged energy storage system 33 fed. The compressed gas tank is as in 2 designed open and has balancing openings D, which can also be located in water turbines, with a and outflowing water drives the turbines. The location of the energy storage system is again in the sea, or in a lake with the earth B. The differential pressure between the water levels W / W 'determines the pressure of the compressed gas G.

The storage operation is maintained here solely by the wind energy. The compressed gas tank 35 is therefore charged arbitrarily.

In the power generation operation, the stored pressurized gas G becomes a torque generator 36 relaxes and torque through an axle to the generator 32 transfer. The generator now supplies the generated power via the power output line 32 ' into the public network N by the switching unit 37 the contacts closes.

The advantage here is the low technical complexity and space requirements in the tower head, since also still eliminates the motor compressor drive. This can save considerable costs. Energy storage can be an intelligent switching unit 37 optimally mix the stored energy.

4 : Here is a central park-like energy storage facility 40 shown several independent energy converters 41a . 41b . 41c , ..., which, however, do not have to supply the standardized power of the public network N. The compressor 44 is operated with the supplied energy and feeds the compressed gas tank 45 that under the platform 48 arranged energy storage system 43 , The compressed gas tank is as in 2 designed open and has balancing openings D, which can also be located in water turbines, with a and outflowing water drives the turbines. The location of the energy storage system is again in the sea, or in a lake with the earth B. The differential pressure between the water levels W / W 'determines the pressure of the compressed gas G.

The memory operation is determined here by the individual energy converters. The compressed gas tank 45 is therefore charged arbitrarily.

In the power generation operation, the stored pressurized gas G becomes a torque generator 46 relaxes and torque through an axle to the generator 42 transfer. The generator now supplies the generated power via the power output line 42 ' into the public network N by the switching unit 47 the contacts closes.

It is advantageous here that several energy converters can use a common compressed gas tank. Technical effort and space requirements are therefore lower and can save considerable costs. Energy storage can be an intelligent switching unit 47 optimally mix the stored energy of all integrated energy converters.

5 : Here is outlined a multi-chamber gas cylinder, which is quite suitable for use in all described energy storage systems.

The pressure chambers 55a , b, c, are arranged so that in the direction of environment a → b → c, the pressure decreases in stages and thus facilitates a structural design for high operating pressures, because only the upcoming differential pressures must be controlled. Another constructive measure is the convex arch shapes which avoid tensile loads. This can also cost-effective materials such. B. use concrete that can absorb mainly pressure loads. The resulting seams are localized and easier to intercept in their load. Volume can be interpreted as the chambers so that the adjacent chambers, for example, have double volume and can absorb the higher pressure from the inner chamber if necessary. A connection via an overpressure mechanism is quite conceivable.

If the electrolysis is provided for storage purposes, z. B. be reserved for water and oxygen two chambers, these gases can be stored here also compacted.

Finally, a chamber may also be designed adiabatically and be filled, for example, as heat capacity with water, which is used to store waste heat, in order later to be able to generate higher pressure by means of a heat pump via a temperature increase in the drive pressure accumulator.

6 : shows a parameter diagram for the volume requirement as a function of the pressure p ₂ in a pressurized gas container, for an energy of [1 ... 10 MWh] generated in 24 h as a parameter.

The ordinate shows the dimensions of an abstracted cube shape as a replacement for a pressurized gas container, if a specific energy generated in 24 h is to be stored under a certain pressure.

Example: A wind turbine delivers 24h evenly 5 MWh, ie 120 MWh. At an allowable pressure of 40 MN / m ² , the abstracted cube shape would have an edge length of about 22 m.

The family of curves also shows that even higher pressures than about 40 MN / m ^2, the required container volume decreases only slowly, the technical complexity but would increase significantly.

7 : a parameter diagram for the temperature change T ₂ as a function of n ₂ [kmol] or m ₂ [t], in a pressurized gas container with the pressure p ₂ as a parameter.

On the basis of this diagram, it can be seen which temperature increase in the compressed gas tank is necessary when compressed air - and thus mass - is taken in the power generation operation in order to maintain the pressure in the compressed gas tank.

Example: In a tank of 1000 m ³ there are 464 t of air with ambient temperature approx. T = 300 K. The initial pressure of p = 40 MN / m ^{2 should be} maintained. With a decrease to 348 t, it would be necessary to increase the temperature in the compressed gas tank to about 400 K or about 100 ° C in order to keep the initial pressure constant. An exothermic reaction of water and oxygen in the pressurized gas container could easily generate this heat energy, especially if the gases were produced on site by electrolysis. Without reheating, the pressure would decrease to about p = 30 MN / m ² at the same temperature. In fact, the temperature decreases even further as a result of the negative mass flow and thus the pressure would drop considerably more. It can be seen how advantageous a reheating can be by combustion or else by heat exchange.

8th a parameter diagram for the stored molar volume n _{2, H2} [kmol] in a compressed gas container, depending on the pressure p ₂ and V as a volume parameter.

The mass of hydrogen represents stored energy, which is released as an enthalpy by reaction with oxygen to produce water (here assumed to be water vapor), which can be calculated using the second formula.

Example: A pressurized gas container has a volume of 1000 m ³ and is pressurized at approx. 18 MN / m ² , then it stores approx. 8000 kmol H ₂ . The stored energy is then E _{(H2O, gas)} = 67.648 · 8000 kWh = 541184 kWh = 541.2 MWh. If one assumes an 8 MWh wind turbine, this would correspond to a storage of 68 h or 2.82 days in full load operation.

Claims (5)

Power generation plant ( 10 ; 20 ; 30 ; 40 ) with at least one energy conversion unit ( 11 ; 21 ; 31 ; 41a . 41b . 41c ), the naturally occurring energy - such as wind, solar, thermal or water energy - directly or indirectly via at least one power generator ( 12a . 12b ; 22 ; 32 ; 42 ) can be converted into electrical current, which via a power output line ( 12a ' . 12b '; 22 '; 32 '; 42 ' ) of the power generator ( 12a . 12b ; 22 ; 32 ; 42 ) is supplied to a public power network (N), wherein an energy storage system ( 13 ; 23 ; 33 ; 43 ), which is a compressor ( 14 ; 24 ; 34 ; 44 ) for the production of compressed gas (G), a compressed gas container ( 15 ; 25 ; 35 ; 45 ; 55 ) for receiving and storing the generated compressed gas (G) and a torque generator ( 16 ; 26 ; 36 ; 46 ) for converting pressure of the compressed gas (G) into mechanical kinetic energy, and wherein the torque generator ( 16 ; 26 ; 36 ; 46 ) a power generator ( 12b ; 22 ; 32 ; 42 ), which determines the mechanical kinetic energy of the torque generator ( 16 ; 26 ; 36 ; 46 Can) to convert into electric power and the public power network (N) out, characterized in that pressure chambers are arranged in the pressure gas tank, that in direction around a → b → c the pressure in stages decreases, that the energy conversion unit ( 11 ; 21 ; 31 ; 41a . 41b . 41c ) and the energy storage system ( 13 ; 23 ; 33 ; 43 ) are designed so that they can operate independently in island operation without connection to the public power grid (N), by electrical energy that does not conform to the standard of the public network, that a switching device ( 17 ; 27 ; 37 ; 47 ) is provided, by means of which the power output line ( 12a ' . 12b '; 22 '; 32 '; 42 ' ) of the power generator ( 12a . 12b ; 22 ; 32 ; 42 ) can be disconnected from the public power grid (N), and that the compressor ( 14 ; 24 ; 34 ; 44 ) directly with energy from the energy conversion unit ( 11 ; 21 ; 31 ; 41a . 41b . 41c ), with only a single power generator ( 22 ; 32 ; 42 ) is provided, wherein the energy storage system ( 13 ; 23 ; 33 ) spatially immediately adjacent to the energy conversion unit ( 11 ; 21 ; 31 ) and that the energy conversion unit ( 11 ; 21 ; 31 ) and the energy storage system ( 13 ; 23 ; 33 ) a constructive unit with a common building platform ( 18 ; 28 ; 38 ) and wherein the compressor ( 34 ) or a supercharger in the tower head of the wind turbine and the power generator ( 32 ) together with the torque generator ( 36 ) are arranged in the tower base. A power plant according to claim 1, characterized in that the energy storage system ( 43 ) by another other energy conversion unit ( 41a . 41b . 41c ) can be supplied with stored electrical energy by switching to island operation. A power plant according to claim 2, characterized in that a plurality of identical or different energy converter units ( 41a . 41b . 41c ) are provided, each to a central energy storage system ( 43 ) are connected. Power generation plant according to one of the preceding claims, characterized in that the pressurized gas container ( 15 ; 25 ; 35 ; 45 ; 55 ) is arranged in a lake or in the sea partly below the water level (W) and in its submerged area pressure equalization openings (D) for inflow or outflow of water, wherein in the pressure equalization openings (D) water turbines are arranged by in the compressed gas container ( 15 ; 25 ; 35 ; 45 ; 55 ) penetrating or emerging from this water can be driven. Power plant according to one of the preceding claims, characterized in that an electrolysis apparatus for splitting water into hydrogen and oxygen is provided, which (with electricity from the energy converter unit 11 ; 21 ; 31 ; 41a . 41b . 41c ) is operated, that the compressed gas container ( 15 ; 25 ; 35 ; 45 ; 55 ) at least three storage chambers ( 55a . 55b . 55c ), of which the first ( 55c ) with hydrogen and the second ( 55b ) with oxygen from the electrolyzer, the third ( 55a ) on the Compressor ( 14 ; 24 ; 34 ; 44 ) can be charged with compressed air, and that additional pressure in the third storage chamber ( 55a by increasing the temperature due to a thermal reaction of hydrogen and oxygen from the other two storage chambers ( 55b . 55c ) can be generated.

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