DE20114745U1 - Device for generating hydrogen - Google Patents

Description

Device for generating hydrogen

The invention relates to a device for the electrochemical production of hydrogen gas (H ₂ ) by applying an electrolysis process for the decomposition of water (H ₂ O) into its components hydrogen (H ₂ ) and oxygen (O ₂ ), wherein the direct current required to carry out the electrolysis is obtained from solar energy.

Virtually any hydrogen compound can be used as a starting material for producing hydrogen (H ₂ ). However, hydrogen is normally produced from water (H ₂ O), which is a cheap starting material and is available in virtually unlimited quantities, and from methane (CH ₄ ) and other hydrocarbons (C _m H _n ), which are obtained in the form of fossil fuels (coal, petroleum and natural gas).

The energy for splitting water (H ₂ O) into its components hydrogen (H ₂ ) and oxygen (O ₂ ) can be supplied in various forms, for example as thermal, electrical or chemical energy.

In order to understand the process used in the solution according to the invention for splitting water (H ₂ O) and alternative solutions which are of technical importance according to the current state of the art, the most important aspects and the boundary conditions of these processes will be briefly discussed below.

P 25654 EN

The so-called "thermolysis" (thermal splitting) of water (H ₂ O) into its two components hydrogen (H ₂ ) and oxygen (O ₂ ) is only partially successful even at very high temperatures, as can be seen from the following table:

Temperature T [K] S [%] 1 ,000 1. 500 2. 000 2. 500 3. 000 3. 500 Degree of dissociation 3 •&Igr;&Ogr;" ⁵ , 020 , 582 4, 21 14 ,4 30 ,9

At a temperature T of 2,500 K (i.e. +2,227 ⁰ C), only about 4% of the water vapor (H ₂ O) has been split into hydrogen (H ₂ ) and oxygen (O ₂ ). Accordingly, the thermolysis of water plays no role in the production of hydrogen.

However, the degree of dissociation α shown in this table refers exclusively to the water fraction that has decomposed into hydrogen (H ₂ ) and oxygen (O ₂ ). In fact, the thermal splitting of water (H ₂ O) produces not only the molecules H ₂ and O ₂ but also radicals such as hydrogen

² "

ions (H ⁺ ) , oxygen ions (O ² ") , hydronium ions

Hydroxide ions (OH") are formed, so that the true degree of dissociation α is considerably larger, especially at higher cleavage temperatures T.

Hydrogen (H ₂ ) can be released from water (H ₂ O) with highly base metals, such as the alkali metals sodium (Na) or potassium (K) or with the alkaline earth metals magnesium (Mg) or calcium (Ca), in a highly exothermic reaction. This is generally represented by a negative sign of the reaction enthalpy AH^ _98. For example, the exothermic reaction of the two reactants sodium (Na) and water (H ₂ O) at a temperature of T ₀ = 298 K produces the products hydrogen (H ₂ ) and Na

hydroxide solution

P 25654 EN

Reduction Oxidation

+ 1 -II

2 H ₂ O

N/a

+ 2 e"

H ₂₍ g)t

+1

OH

_(aq)

Redox reaction: 2 Na _(f) + 2 H ₂ O ₁ ^, -» 2 Na ⁺ _(aq) + 2 0H' _(aq , +&EEgr; ₂₍₉₎ &Tgr;

with AHj ₉₈ » -335 kJ.

In this reaction, Na and Na ⁺ form a first corresponding redox pair, with sodium (Na) as a reducing agent
and the resulting sodium ions (Na ⁺ ) act as oxidizing agents. It is coupled with a second corresponding redox pair consisting of H ₂ O and OH", whereby water (H ₂ O) acts as the oxidizing agent and hydroxide ions (OH") formed in this reaction serve as the reducing agent.

Superscript Roman numerals symbolize the oxidation numbers of the respective element. The expressions in brackets refer to the state of aggregation or solution of the respective substance, as can be seen in the following table:

abbreviation Aggregate or
Solution state (f) firmly (fi) fluid (G) gaseous (aq) Cations or anions
in aqueous solution

The reaction enthalpy of this reaction is given by the symbol

298

which expresses that the energy released in this reaction under standardized conditions

&Ggr;&ngr;*"

P 25654 DE " * '··* ♦ ·' *,.* .·.

conditions, i.e. at normal pressure (po = 1,013 mbar) and normal temperature (T ₀ = 298 K = +25 ⁰ C).

In a similar way to the reaction of sodium (Na) and water (H2O), hydrogen (H2) is also obtained, for example, by the reaction of potassium (K) with water (H2O) to form potassium hydroxide (KOH):

2 K _(f) + 2 H ₂ 0 _(fl) -+ 2 K ⁺ _(aq) + 2 0H", _aq , + H _2(g) t with the reaction enthalpy AHj ₉₈ < 0.

In this reaction, K and K ⁺ form a first corresponding redox pair, with potassium (K) acting as a reducing agent and the resulting potassium ions (K ⁺ ) acting as an oxidizing agent. The second corresponding redox pair again consists of H2O and OH", with water (H ₂ O) acting as an oxidizing agent and the hydroxide ions (OH") formed in this reaction serving as a reducing agent.

Furthermore, hydrogen (H ₂ ) can also be produced by the reaction of magnesium (Mg) with water vapor (H ₂ O) to form magnesium oxide (MgO):

Reduction: H ₂ 0 _(g) -» H _2(g) t + <0> Oxidation: Mg _(f) + <0>-> MgO _(f)

Redox reaction: Mg _(f) + EEgr; ₂ O( ₉ ) ~> MgO _(f) + H _2(g) t

with AH ^R » -260 kJ.

Here, the alkaline earth metal magnesium (Mg) takes on the role of a reducing agent and water (H ₂ O) that of an oxidizing agent. The angle brackets indicate that the atomic oxygen (0) formed during the reduction is not free

P 25654 DE " * *· ··' '..' .:,

5
but immediately after its creation with the

existing magnesium (Mg) to form magnesium oxide (MgO).

In a similar way, hydrogen (H2) is obtained, for example, by reacting calcium (Ca) with water (H ₂ O) to form calcium hydroxide (Ca(OH) ₂ ):

Ca _(f , + 2 H ₂ 0 _(fl) -» Ca ²⁺ _(aq) + 2 0H" _(aq) + H _2(g) t with the enthalpy of reaction AH^ ₉₈ < 0,

where the alkaline earth metal calcium (Ca) acts as a reducing agent and water (H ₂ O) serves as an oxidizing agent.

Iron (Fe) can also be converted into iron (III) oxide (Fe ₂ O ₃ ) and hydrogen (H ₂ ) at high temperatures with water vapor (H ₂ O):

Reduction: H ₂ 0 _(g) -» H _2(g) t + <0> |-3

Oxidation: 2 Fe _{f) + 3 <0> -» Fe ₂ O _3(f)

Redox reaction: 2 Fe _{f) + 3 H ₂ 0 _(g) -> Fe ₂ O _3{f) + 3 H _2(g) t

with Δ�EEgr; ^�Kgr; > 0.

To a limited extent, the decomposition of water (H ₂ O) by red-hot iron (Fe) at around +500 ⁰ C is also used to produce hydrogen. This reaction produces the products iron(II) oxide (FeO) and hydrogen (H ₂ ), with iron (Fe) being oxidized to iron(II) oxide and water (H ₂ O) being reduced to hydrogen (H ₂ ), as can be seen from the following reaction equation:

H ₂ O _(g) + Fe _(f) FeO _(f) + H _{2 (g)} T,

&ugr;·' -i Nj &pgr;

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6
where iron (Fe) acts as a reducing agent and water (H ₂ O)

serves as an oxidizing agent.

As can be summarized, the processes occurring in the above-mentioned reactions are based on the fact that all of the metals mentioned (Na, K, Mg, Ca, Fe) are able to reduce water (H ₂ O) to hydrogen (H ₂ ).

Since practically all non-metals can only split water (H ₂ O) with the addition of energy, they play no role in hydrogen production in the laboratory. However, one possibility for producing small amounts of hydrogen in an exothermic reaction is to react water (H ₂ O) with calcium hydride (CaH ₂ ):
15

CaH ₂ <f) + 2 H ₂ O(JT ₁ ) -> Ca (OH) _2(aq) + 2 H _2(g) T

with the reaction enthalpy AHj ₉₈ * -955 kJ.

Approximately 1 m ³ of hydrogen (H ₂ ) is released from 1 kg of calcium hydride (CaH ₂ ).

Calcium hydride (CaH ₂ ) can be produced in the laboratory at 400 ⁰ C by passing hydrogen (H ₂ ) over calcium (Ca) in an exothermic reaction:
25

Ca(f) + H2(g) > CaH ₂₍ f)

with the binding enthalpy Δ�EEgr; ^β » -779 kJ-mol" ¹ .

This makes it possible to store hydrogen (H ₂ ) as calcium hydride (CaH ₂ ) and later release hydrogen (H ₂ ) with the help of water (H ₂ O).

Hydrogen can now also be produced in the laboratory by the action of acids (H _n A) '^^'BaA^^IOH^);on"i&§d:Ce metals such as zinc

\ ^&bgr;

P 25654 DE ** ^&bgr; ·· ·· \. ^&bgr; ..\

(Zn) or iron (Fe). The formula symbols used are explained as follows:

A: Acid residue (e.g. BO^" , CO^ , Cl" , NΩ3 , PO ³ , , SO^ ^- , HCOO") ,

B: base residue (e.g. Ca ²⁺ , Li ⁺ , Na ⁺ , K ⁺ , Al ³⁺ ),

η 6 N: basicity of the acid residue A (usually: η < 3), m 6 N: acidity of the base residue B (usually: m < 3).

For this purpose, the so-called "Kipp apparatus" is used, which is also suitable for the production of many other gases in the laboratory, such as for the production of carbon dioxide (CO ₂ ), oxygen (O ₂ ) or chlorine (Cl ₂ ). It consists of a spherical funnel and a development vessel with a constriction. The funnel and development vessel are connected to one another by a ground glass joint in such a way that the long connecting tube of the funnel extends into the lower part of the development vessel without interrupting the connection between the two volumes of the development vessel. The metal (Me) is in the middle part of the apparatus, and the upper and lower parts contain an acid (H _n A). If the tap in the middle part is opened, the acid (H _n A) flows from the upper to the lower part due to the excess pressure of the liquid column, finally coming into contact with the metal (Me) in the middle part and reacting with it to form hydrogen (H ₂ ). If the tap is closed, the contact between acid (H _n A) and metal (Me) is interrupted and the evolution of gas comes to a halt. In this way, the evolution of hydrogen can be started and stopped again by opening and closing the tap.

An example of the release of hydrogen by the action of an acid (H _n A) on a metal (Me) is the reaction of zinc £Z*$^*withs**§§Tgs4ur: ^ClT/ «Djisän djig E&nwirkung

P 25654 DE ** * ·· ··* "&diams;·*

of hydrochloric acid (HCl) on zinc (Zn), the metal is slowly dissolved with the development of hydrogen (H ₂ ) and zinc chloride (ZnCl ₂ ), as can be seen from the following redox reaction:

+ 1 -II _!

Reduction: 2 H ₃ O ⁺ _(aq) + 2 Cl" _(aq) + 2 e"

+ 1 -II 0 -I

-* 2 H ₂ O _(fl) + H _2(g) t + 2 Cl"(aq)

0 +11

Oxidation: Zn _(f) -> Zn ²⁺ _(aq) + 2 e"

Redox reaction: Zn _(f) + 2 HCl _(aq) -> ZnCl _2(aq) + H _2(g) t

with AH^ ₉₈ < 0 (exothermic reaction) .

In this case, zinc (Zn) acts as a reducing agent and hydrochloric acid (HCl) as an oxidizing agent. 15

For the production of hydrogen (H ₂ ) in the laboratory, the reactions of the metals aluminium (Al) and silicon (Si) with hot sodium hydroxide solution (NaOH) can also be used:

Al( _f) +Na ⁺ _(aq) +0H" _(aq) + 3 H ₂ O _1n , -> Na ⁺ _(aq ) + Al(OH)" _(aq) +l,5H _2(g) T, Si (f) + 2 Na ⁺ Oq) + 2 0H" _(aq) + H ₂ 0 _(f i, ->- 2 Na ⁺ _(aq) + SiO*" _(aq) + 2 H _2{g) t.

In the first case, 27 g (ie 1 mol) of aluminium (Al) are required to produce 33.6 l (ie 1.5 mol) of hydrogen (H ₂ ), i.e. about 1.2 m ³ per kg of aluminium (Al). In the second case, 28 g (ie 1 mol) of silicon (Si) are required to produce 44.8 g (ie 2 mol) of hydrogen (H ₂ ).

Another technical possibility for producing hydrogen (H ₂ ) is the so-called "electrolysis" of water (H ₂ O).

P 25654 EN ' * ·· *·.* .1.

Since the intermolecular bond between hydrogen and oxygen in the water molecule (H2O) is very strong, it can only be broken in an endothermic reaction (represented by a positive sign of the reaction enthalpy AHj ₉₈ ) by supplying large amounts of energy:

+ 1-11

+ 1 -II

Reduction (cathode) : 2 H ₃ O ⁺ _{aq) + 2 e -► H _{2 (g)} T + 2 H ₂ O _{f i)

- ^{11 +} i +1 -11 0 Oxidation (anode) : 4 OH" _(aq ) -» 2 H ₂ O _(f i) + O _{2 (g)} T + 4 e"

Redox reaction: 2 H ₂ O _1n , 2 H _{2 (g)} T + O _{2 (g)} t

with AHj ₉₈ « +242 kJ.

The energy consumption for the electrolytic production of 1 m ³ of hydrogen (H ₂ ), which is produced in addition to 0.5 m ³ of oxygen (O ₂ ), amounts to around 4.5 kWh.

The decomposition of water (H ₂ O) into its components hydrogen (H ₂ ) and oxygen (O ₂ ) can be carried out, for example, in a "Hofmann decomposition apparatus". For this purpose, the apparatus, which consists of three interconnected glass tubes, is filled with water (H ₂ O) through the funnel-shaped inlet of the middle tube so that the two outer tubes are filled with water up to the taps - which are then closed. In the lower part of each of the two outer tubes there is a small sheet of platinum (Pt) with a platinum wire leading outwards. As soon as the platinum wires are connected to a direct current source of sufficient voltage, small gas bubbles begin to rise from the platinum sheets (the "electrodes"): The water (H ₂ O) is electrolytically decomposed to form hydrogen (H ₂ ) and oxygen (O ₂ )..wpbe.4..the ftfasserstoff

P 25654 EN * '

(&EEgr;2) - a combustible gas that does not support combustion - is formed at the electrode connected to the negative pole of the power source ("cathode"), while oxygen (O2) - a non-combustible gas that does support combustion - is developed at the electrode connected to the positive pole of the power source ("anode"). Since pure (distilled) water is a very poor conductor of electricity, water that has been made more conductive by acidification with sulphuric acid (H2SO4) is used for electrolysis. When determining the mass ratios in which hydrogen (H2) and oxygen (O2) occur during the electrolytic decomposition of water (H2O) described above, it can be determined that hydrogen (H2) and oxygen (O2) are formed in a ratio of 1:7.936.

Technically, this method is basically used today by connecting several hundred decomposition cells in series. The first electrode of the first cell is usually made of nickel (Ni) and connected to the positive pole (anode) of the power source. The last electrode of the last cell, on the other hand, is made of iron (Fe) and connected to the negative pole (cathode) of the power source. Nickel-plated iron sheets are used for the middle electrodes on the anode side as bipolar electrodes (i.e. acting as a cathode in one cell and anode in the adjacent cell). A porous partition ("diaphragm") that allows the current to be transported prevents the hydrogen (H2) formed at the cathode and the oxygen (O2) formed at the anode from combining to form water ( _H2O ) in each cell in a highly exothermic, explosive oxyhydrogen reaction:

2 _H2 (g) + _O2 (g) - > 2 H ₂ O(fl)

with the binding enthalpy AHj ₉₈ » -286 kJ-mol" ¹ .

&bull; I ·

P 25654 EN ** ··

To increase the conductivity of water (H ₂ O), it is usually mixed with sodium hydroxide (NaOH) or potassium hydroxide (KOH). Aqueous solutions of table salt (NaCl) can also be used for electrolysis. The hydrogen (H2) produced in this way is a sought-after product due to its purity.

Another example of an electrolysis process for producing hydrogen (H2) is the so-called "chlor-alkali" electrolysis. This process is used in industry to produce chlorine (CI2) and hydrogen ( _H2 ). By evaporating the solution, sodium hydroxide solution (NaOH) can also be obtained. During the electrolysis of an aqueous solution of table salt (NaCl), hydrogen ( _H2 ) escapes at the cathode and chlorine ( _Cl2 ) at the anode:

+&igr;+&igr;-&ugr;

Reduction (cathode): 2 Na ⁺ _(aq) + 2 H ₃ O ⁺ _(aq) + 2 e"

+ 1 +1 -II 0

-> 2 Na ⁺ _(aq) + 2 H ₂ O _(fl) + H ₂₍ g,t

+ 1 -II +1 -II -II +1

(with 2 H ₂ O _(fl) ±5 H ₃ O ⁺ _(aq) + OH" _(aq)

-i 0
Oxidation (anode): 2Cl~ _(aq) -> Cl _2ig) T + 2e~

Redox reaction: 2 H ₂ 0 _(f i) + 2 Na ⁺ _(aq) + 2 Cl~ _(aq)

-> Cl _2(g) t + H ₂ (g)t + 2Na ⁺ _(aq) +2 0H" _(aq)

The chloride ions (Cl") migrate to the anode and are discharged there. In contrast, the sodium ions (Na ⁺ ) are not discharged because the hydronium ions (H30 ⁺ ) are easier to reduce than the sodium ions (Na ⁺ ).

During the chlor-alkali electrolysis described above, care must be taken to ensure that the products do not mix with one another: &Hnnenv:*cia*Chrör: ^Cl ₂ J'&bull;m.ii"Nat;rqnl«auge (NaOH) &bull; · · · ·· : .:. : : : ··· ·· ·&iacgr;·

P 25654 DE ** * ** ·· *··' **.

would react in a hydrolytic disproportionation reaction to form sodium chloride (NaCl) and hypochlorous acid (HOCl):

Cl ₂ (g) +NaOH _(aq) -» NaCl (aq) + H0Cl _(aq ).

In this reaction, the oxidation state "0" of the element compound of chlorine (CI2) is converted into the higher oxidation state "+I" (in HOCl) and the lower oxidation state "-I" (in NaCl).

Since hydrogen (H ₂ ) and chlorine (Cl ₂ ) form a dangerous, highly explosive mixture and when mixed under the influence of light, by an ignition spark or at temperatures above +250 ⁰ C in the context of a strongly exothermic chlorine detonation reaction

Cl ₂ (g)+H ₂₍ g) -» 2HCl(g)t with AHj ₉₈ « -92 kJ-mol" ¹

to hydrochloric acid (HCl), it must also be ensured that the products obtained during chlor-alkali electrolysis, hydrogen (H ₂ ) and chlorine (Cl ₂ ), cannot mix with each other. For this purpose, the anode and cathode chambers are separated from each other by a diaphragm made of asbestos or plastic. Only ions can pass through this diaphragm, while the gases formed, hydrogen (H ₂ ) and chlorine (Cl ₂ ), are separated.

In addition to various possibilities for producing hydrogen (H ₂ ) from water (H ₂ O), hydrogen production based on hydrocarbons is also technically relevant today. Hydrocarbons are generally exothermic compounds, i.e. their decomposition into the components hydrogen (H ₂ ) and carbon (C) can only occur with the addition of energy -

albeit to a lesser extent than with. dej;..splitting of what- :··.:&mdash; .··. .*·. .; ·· · . ***. ^: : . :.. : : *: : : :·* ·: : : · :.:. _: ··» : : : :

P 25654 EN

i I &iacgr;

13
water (H2O). A simple example of this is the

Decomposition of methane (CH ₄ ):

) £+ C(f) + 2 H ₂ (g)T

with the reaction enthalpy AH ^R « +75 kJ.

Hydrogen is produced technically by supplying thermal and electrical energy.

The starting point of the so-called "thermal hydrocarbon cracking" is hard coal, which at around +1,100 to +1,300 ⁰ C in the absence of air turns into "coke oven gas" consisting of hydrogen (H ₂ ) and methane (CH ₄ ) in addition to coke and coal tar. Hydrogen (H2) can be separated from this gas mixture by low-temperature fractionation. The proportion of hydrogen (H2) produced in the total volume of the products is between 60 and 64%. In a similar way, hydrogen (H2) can also be produced in addition to carbon (C) by heating petroleum ("cracking").

In "chemical hydrocarbon cracking", the thermal hydrocarbon cracking process is combined with an oxidation of the carbon (C) formed in the process, whereby the oxygen (O2) required for the oxidation process is taken from the water (H ₂ O). If methane (CH ₄ ) is used as the starting material, the following reaction in the presence of nickel (Ni) as a catalyst with the addition of energy produces "cracked gas" consisting of 1 mol of carbon monoxide (CO) and η mol of hydrogen (H ₂ ), where η > 2:

CH ₄ Jg) + H ₂ O(g)

[Ni]

C0(g,T + 3 H ₂ (g,t

with the reaction enthalpy AH ^R « +206 kJ,

&bull; *

P 25654 DE ** * ** ·· *·** .J

Today, hydrogen (H2) is produced on a large scale mainly by reducing water (H ₂ O) with carbon (C) in an endothermic reaction. To do this, water vapor (H ₂ O) is passed over bright red glowing coke (C) at around +800 to +1,000 ⁰ C:

Cm +H ₂ O _(g) ±5 C0 _(g) t+ H _2(g) t with the reaction enthalpy AH ^R « +131 kJ.

The gas mixture produced in the endothermic reaction, consisting of 1 mole each of carbon monoxide (CO) and hydrogen (H ₂ ), is called "water gas" or "synthesis gas". The energy requirement for this reaction, known as "coal gasification", can be covered by partially burning the coal.

The carbon monoxide (CO) formed can be further oxidized to carbon dioxide (CO ₂ ) at low temperatures in an exothermic reaction with water vapor (H ₂ O) to form new hydrogen (H ₂ ):

C0 _(g , +H ₂ 0 _(g) ±5 C0 _2(g) t+ H _2(g) t with the reaction enthalpy ΔEEgr; ^Kgr; « -47 kJ,

so that with excess water vapour and less high temperatures the overall reaction

C _(f) + 2 H ₂ 0 _(g) U CO ₂ (g,t + 2 H _{2 (g)} t with the reaction enthalpy ΔEEgr; ^Kgr; « +90 kJ

can take place. The separation of carbon monoxide (CO) from water gas described above is known under the name "carbon oxide conversion".

P 25654 DE II t · ; ; \..* . &Ggr; · ·

15
OBJECT OF THE PRESENT INVENTION

Based on the above-mentioned prior art, the present invention is dedicated to the task of providing a device with the aid of which a cost-effective energy supply for the electrolytic decomposition of water (H ₂ O) into the components hydrogen (H ₂ ) and oxygen (O ₂ ) is made possible.

This object is achieved according to the invention by the features of the independent patent claims. Advantageous embodiments which further develop the idea of the invention are defined in the dependent patent claims.

SUMMARY OF THE PRESENT INVENTION

In order to solve the problem defined in the previous section, the underlying invention proposes an efficient device for the electrolytic decomposition of water (H ₂ O) into the components hydrogen (H ₂ ) and oxygen (O ₂ ) with the aid of a Hofmann decomposition apparatus, wherein the direct current required for the electrolysis processes taking place inside the apparatus is obtained from solar energy.

For this purpose, a steam turbine is used that drives a direct current generator. The water vapor required to operate the steam turbine is generated by focusing the sun's rays on a water boiler filled with water (H ₂ O).

In addition, according to the invention, at least part of the alternating current required to operate a refrigeration unit for the safe storage of hydrogen gas (H ₂ ) is generated from solar energy. For this purpose, in addition to the above-mentioned direct current generator, the steam turbine is connected to

P 25654 DE »It**· ·*···· · &idigr; *5

16
Another AC generator is connected, which generates the

Refrigeration unit supplied with alternating current.

BRIEF DESCRIPTION OF THE DRAWINGS
5

Further properties, features, advantages and applications of the underlying invention result from the subordinate dependent claims and from the following description of the preferred embodiment of the invention, which is shown in the following drawings. -■'"" Herein show:

Fig. 1 is a schematic representation of the system 100 according to the invention to illustrate the components required for the production of hydrogen (H ₂ ) according to the preferred embodiment of the underlying invention,

Fig. 2 shows a heat-resistant first water boiler 200 filled with water (H ₂ O), which is required for the generation of steam to drive a steam turbine 110,

Fig. 3 shows a hydraulic device 300 for fine positioning of an optical lens 102, which serves to focus incident solar rays onto the first water tank 200 arranged underneath and filled with water,

Fig. 4 shows an arrangement 400 for generating energy using the steam turbine 110, connected to a direct current generator 112 and an alternating current generator 114,

P 25654 EN

17
Fig. 5 a Hofmann decomposition apparatus 500 for

Carrying out the electrolytic decomposition of water (H ₂ O), in which the two gases hydrogen (H ₂ ) and oxygen (O ₂ ) are produced by supplying energy in the form of direct current, and

Fig. 6 a refrigeration unit 600 for the safe storage of the resulting hydrogen (H ₂ ).

DETAILED DESCRIPTION OF THE INVENTION

In the following, the functions of the modules included in the preferred embodiment of the present invention, as shown in Figures 1 to 6, are described in more detail.

Referring to Fig. 1, the present invention will first be explained schematically. A simplified overview diagram of the system 100 according to the invention is shown to illustrate the components required for the production of hydrogen (H ₂ ) according to the preferred embodiment of the underlying invention. This system 100 consists of

- an optical lens 102 for focusing incident solar rays onto a first water vessel 200 filled with water (H ₂ O) to generate water vapor,

- a hydraulic device 300 for fine positioning of the optical lens 102, consisting of a photocell 104 as an optical sensor element, hydraulic actuator elements 106 and a computer-aided control and regulation system 108,

P 25654 EN

» &igr;

»

18
- a steam turbine 110 with a connected direct current generator 112 or alternating current generator 114 for generating energy for the production and safe storage of hydrogen (H2),

- a second water tank 116 of a Hofmann decomposition apparatus 500 filled with water (H2O) for producing hydrogen (H2) in the course of an electrolytic decomposition of water (H2O), in which the two gases hydrogen (H2) and oxygen (O2) are produced, and

- a refrigeration unit 118 for cooling and storing the resulting hydrogen (H ₂ ).

Fig. 2 shows a first water boiler 200 filled with water (H2O), which can be filled via a supply pipe 202 attached to the side. Due to the effect of the sun's rays bundled with the aid of an optical lens 102, the water (H2O) can be heated within a few minutes to such an extent that the boiling point of the water (T _K/ h2O = 100 ⁰ C) is exceeded and water vapor is produced.

The hydraulic device 300 shown in Fig. 3 shows the optical lens 102, which is mounted on four hydraulic actuator elements 106 above the first water tank 200 filled with water (H ₂ O). With the help of a photocell 104 as an optical sensor element and a combined regulation and control system 108, consisting of a connected computer, the position of the optical lens 102 can be changed in such a way that incident sun rays are focused on the water (H ₂ O) in the water tank 200. In this way, the yield of solar energy for heating the water (H ₂ O) can be maximized.

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As can be seen from the arrangement 400 shown in Fig. 4, in the preferred embodiment of the underlying invention, the released steam is used to drive a downstream steam turbine 110 which is connected to a direct current generator 112 and an alternating current generator 114.

The direct current generated by the direct current generator 112 is used according to the invention for the electrolytic decomposition of water (H2O), which, as shown in Fig. 5, is located in a second water container 116. The Hofmann decomposition apparatus 500 shown here illustrates the process of this chemical reaction, in which the two gases hydrogen (H2) and oxygen ( _O2 ) are produced when energy is supplied in the form of direct current. These collect on two oppositely charged electrodes 116a+b immersed in the water ( _H2O ) and can be sucked up with the help of two discharge pipes 117a+b and fed into storage containers connected to them. As can be seen from Fig. 5, the released hydrogen ( _H2 ) accumulates on the negatively charged electrode 116a (cathode), while the oxygen ( _O2 ) produced concentrates around the positively charged electrode 116b (anode).

In order to safely store the hydrogen (H ₂ ) produced and to prevent an explosive exothermic oxyhydrogen reaction with the oxygen (O ₂ ) in the ambient air, the hydrogen (H ₂ ) must be cooled to a storage temperature T _l ,h2 of -230°C to -260 ⁰ C using a refrigeration unit 118. According to the invention, the alternating current generated by the alternating current generator 114 can be used to operate this refrigeration unit 118, as shown in Fig. 6.

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&bull; f

The meaning of the symbols provided with reference numerals in Figures 1 to 6 can be found in the attached list of reference numerals.

P 25654 EN

List of reference symbols

No. Symbol

Schematic representation of the plant according to the invention to illustrate the components required for the production of hydrogen (H2) according to the preferred embodiment of the underlying invention

optical lens for focusing incident sun rays onto a heat-resistant first kettle filled with water (H ₂ O)

Photocell as optical sensor element for determining the current position of the optical lens

hydraulic actuator elements for fine positioning of the optical lens

Computer-aided control and regulation system for controlling the hydraulic elements

Steam turbine with one connected DC generator 112 or AC generator

DC generator for generating energy for the production of hydrogen (H ₂ ) in electrolysis

Alternating current generator for generating energy for the operation of a refrigeration unit 118 for the safe storage of the resulting hydrogen (H ₂ )

second water tank filled with water (H ₂ O) for producing hydrogen (H ₂ ) by electrolytic decomposition of water (H2O) which produces the two gases hydrogen (H2) and oxygen (O ₂ )

Negatively charged electrode (cathode) for the collection of hydrogen (H ₂ ) produced during the electrolysis of water (H ₂ O) in the Hofmann decomposition apparatus 500

positively charged electrode (anode) for the collection of the oxygen produced during the electrolysis of water (H ₂ O) in the Hofmann decomposition apparatus 500.t.gf fß .(0 _£

P 25654 EN

No.

symbol

117a

Discharge pipe for the resulting hydrogen (H2)

117b

Discharge pipe for the resulting oxygen (O2)

118

Refrigeration unit for cooling and storing the resulting hydrogen gas (H2)

200

heat-resistant first water boiler filled with water (H2O), which is needed to generate steam to drive a steam turbine

202

Supply pipe for filling the first water boiler 200 with water (H2O)

300

computer-controlled hydraulic device for fine positioning of the optical lens 102, which serves to focus incident solar rays onto the first water tank 200 arranged underneath and filled with water

400

Arrangement for generating energy using the steam turbine 110, which operates the direct current generator 112 and the alternating current generator 114

500

Hofmann decomposition apparatus for carrying out the electrolytic decomposition of water (H ₂ O), in which the two gases hydrogen (H2) and oxygen (O2) are produced by supplying energy in the form of direct current

502

Water (H ₂ O) as starting material for electrolytic decomposition to produce hydrogen (H ₂ ) and oxygen (O ₂ )

504

Negatively charged electrode (cathode) for the accumulation of hydrogen gas (H ₂ ) produced during the electrolysis of water (H ₂ O)

506

positively charged electrode (anode) for the accumulation of oxygen gas (O ₂ ) produced during the electrolysis of water (H ₂ O)

508

Hydrogen gas (H ₂ ) released during the electrolytic decomposition of water (H ₂ O)

510

Oxygen gas (O ₂ ) released during the electrolytic decomposition of water (H ₂ O)

P 25654 EN

symbol

Glass flask for collecting the hydrogen gas (H ₂ ) released during the electrolysis of water (H2O)

Glass flask for collecting the oxygen gas (O2) released during the electrolysis of water (H2O) Refrigeration unit for the safe storage of the hydrogen gas (H2) produced

Supply pipe for supplying the hydrogen gas (H ₂ ) produced during electrolysis to the refrigeration unit

Claims (6)

1. Plant for the electrolytic decomposition of water (H ₂ O) into its components hydrogen (H ₂ ) and oxygen (O ₂ ), comprising: - a Hofmann decomposition apparatus ( 500 ), the electrolyte solution of which consists of water (H ₂ O) mixed with acid, and - an energy source ( 112 ) for supplying power to the Hofmann decomposition apparatus, characterized in that the direct current required for the electrolysis processes taking place inside the Hofmann decomposition apparatus ( 500 ), which is provided by the energy source ( 112 ), is obtained from solar energy. 2. Plant according to claim 1, characterized in that a direct current generator ( 112 ) driven by at least one steam turbine ( 110 ) is used as an energy source to provide the direct current for the electrolysis processes inside the Hofmann decomposition apparatus ( 500 ). 3. Plant according to one of the preceding claims, wherein said plant ( 100 ) additionally has a refrigeration unit ( 118 ) for cooling and storing the hydrogen (H ₂ ) produced during electrolysis, characterized in that at least part of the alternating current required for the operation of the refrigeration unit ( 118 ) is also generated from solar energy. 4. Plant according to claim 3, characterized in that an alternating current generator ( 114) is used to provide the alternating current for operating the refrigeration unit (118 ) , which is driven by at least one steam turbine ( 110 ). 5. Plant according to one of claims 2 and 4, additionally comprising: - at least one water boiler ( 200 ) filled with water (H ₂ O) in which steam is generated using solar energy, and - at least one optical lens ( 102 ) for focusing incident solar rays on said water tank ( 200 ), characterized in that the water vapor for operating the steam turbine ( 110 ) is generated by focusing solar rays with the aid of the optical lens ( 102 ) onto the water boiler ( 200 ) filled with water (H ₂ O) for the purpose of heating the water (H ₂ O) contained therein. 6. System according to claim 5, characterized by a computer-controlled hydraulic device ( 300 ) for positioning the optical lens ( 102 ), consisting of at least one optical sensor element ( 104 ), at least one hydraulic actuator element ( 106 ) and a computer-aided control and regulation device ( 108 ).