Device and Method for Photovoltaic Generation of Hydrogen

Abstract

The invention relates to a device and a method for the photo-voltaic generation of hydrogen from hydrogen-containing compounds, sunlight being concentrated on solar cells by means of an optical concentrator and the consequently generated voltage being used directly for the electrolysis of a hydrogen-containing compound, in particular deionised water, in order to generate hydrogen.

1 . A device for the generation of hydrogen from hydrogen-containing compounds, comprising. 
 a plurality of units made of respectively at least one optical concentrator for concentrating sunlight onto at least one solar cell, and    at least one solar cell which is not in contact with the hydrogen-containing compounds and is electrically connected to an electrolysis unit which has an anode and a cathode in contact with the hydrogen-containing compounds,    wherein the units are disposed on a tracking system following the position of the sun.    
   
   
       2 . The device according to  claim 1 , wherein each unit has an electrical power of less than 100 watts.  
   
   
       3 . The device according to  claim 1 , wherein the electrolysis unit has an operating temperature of −10° C. to 200° C., in particular of 30° C. to 100° C.  
   
   
       4 . The device according to  claim 1 , wherein the optical concentrator is a point-focusing lens, Fresnel lens or a line-focusing lens.  
   
   
       5 . The device according to  claim 1 , wherein the optical concentrator is a parabolic mirror with a line focus.  
   
   
       6 . The device according to  claim 1 , wherein the optical concentrator is a dished mirror with a point focus.  
   
   
       7 . The device according to  claim 1 , wherein the solar cell consists of a plurality of layers of semiconductor materials which are connected to each other in series and have respectively different band gap energy.  
   
   
       8 . The device according to  claim 7 , wherein the semiconductor materials are selected from the group consisting of silicon, germanium and ITT-V compounds of aluminium, gallium, indium, nitrogen, phosphorus, arsenic and antimony.  
   
   
       9 . The device according to  claim 8 , wherein the solar cell has an np polarity.  
   
   
       10 . The device according to  claim 1 , wherein the solar cell has a pn polarity.  
   
   
       11 . The device according to  claim 1 , wherein the solar cell has a pn or np transition and a voltage of more than one of: 1.4 V, and 1.6 to 2.4 V.  
   
   
       12 . The device according to  claim 1 , wherein the solar cell has a plurality of series-connected pn or np transitions and has a voltage in the range of 1.5 to 6 V.  
   
   
       13 . The device according to  claim 1 , wherein the solar cell has an area of 0.01 to 1 cm 2 .  
   
   
       14 . The device according to  claim 1 , wherein the electrolysis unit contains a proton-permeable polymer membrane (PEM) which is in direct contact with the cathode and the anode.  
   
   
       15 . The device according to claims  1 , wherein the anode and the cathode to includes at least one of: 
 noble metals, taken from the group consisting of: palladium and iridium, the compounds thereof, iridium oxide, and    metals coated with noble metals, taken from the group consisting of: iron or copper.    
   
   
       16 . The device according to  claim 1 , wherein a distribution structure, having a metal grating, is disposed on the electrodes in order to distribute the current.  
   
   
       17 . The device according to  claim 1 , wherein at least one channel or a gas-permeable material is disposed at the cathode in order to discharge the generated hydrogen.  
   
   
       18 . The device according to  claim 17 , wherein the channel and/or the coating on a side orientated towards the light is light-impermeable or metal-coated.  
   
   
       19 . The device according to  claim 1 , wherein the hydrogen-containing compound is of deionised water in substantial parts.  
   
   
       20 . The device according to  claim 1 , wherein the electrolysis unit consists of a plurality of series-connected units consisting of electrodes and proton-permeable membranes.  
   
   
       21 . A method for the generation of hydrogen from hydrogen-containing compounds, in which sunlight is concentrated on at least one solar cell by means of an optical concentrator and, with the photovoltaically generated voltage, the hydrogen-containing compounds are electrolysed and the protons formed by the electrolysis are conducted from the anode to the cathode where they are reduced to form molecular hydrogen, a plurality of units being used which track the position of the sun and consist of at least one concentrator and at least one solar cell which is not in contact with the hydrogen-containing compounds and is contacted electrically with an electrolysis unit with a cathode and an anode.  
   
   
       22 . The method according to  claim 21 , wherein solar cells consisting of a plurality of pn or np transitions which are connected to each other in series and consist of semiconductor materials which have respectively different band gap energy are used.  
   
   
       23 . The method according to  claim 21 , wherein the semiconductor materials are selected from the group consisting of silicon, germanium and ITT-V compounds of aluminium, gallium, indium, nitrogen, phosphorus, arsenic and antimony.  
   
   
       24 . The method according to  claim 21 , wherein the number of pn or np transitions of the solar cell is chosen such that the solar cell has a voltage in the range of 1.5 to 6 V.  
   
   
       25 . The method according to  claim 21 , wherein the light is concentrated by the factor of one of: 50 to 1500, and 300 to 1000.  
   
   
       26 . The method according to  claim 21 , wherein the light is concentrated with a point-focusing Fresnel lens, a point-focusing dished mirror, a line-focusing optical lens or a parabolic mirror.  
   
   
       27 . The method according to  claim 21 , wherein a proton-permeable polymer membrane is used as electrolysis unit.  
   
   
       28 . The method according to  claim 21 , wherein the hydrogen from the units is assembled and collected.  
   
   
       29 . The method according to  claim 21 , wherein the generated hydrogen is discharged via a channel system.  
   
   
       30 . The method according to  claim 21 , wherein the hydrogen-containing compounds are used for cooling in that the hydrogen-containing compounds are made to flow along the solar cells.  
   
   
       31 . The method according to  claim 21 , wherein molecular oxygen is generated as by-product.  
   
   
       32 . The method according to  claim 21 , wherein the hydrogen-containing compound consists of deionised water in substantial parts.