Spannungsfelder der Bioenergie anhand von Eindrücken aus Brasilien:
Physikalisches Grundprinzip der elektrochemischen Kohlehydrierung: Thermodynamische Kohlehydrierung braucht Druck und Temperatur
Kann Druck durch hohe Dichte von Wasserstoffionen im Elektrolyt ersetzt werden?
Kann Temperatur durch elektrochemische Spannung ersetzt werden?
Eine Studie von Dipl.-Ing. Dr. Friedrich Kröner und Dipl.-Ing. Zeljka Kröner.
| Nr, | Reaktion | Description | Energy required kJ/mol |
|---|---|---|---|
| 1 | 2 H2O + Ptel → H2↑ + 2OH- + Ptsf | Alkaline hydrogen electrolysis | 153 |
| 2 | 2 H2O + Ptel → 2Hcs + 2OH- | Alkaline hydrogen chemisorptions | 152 |
| 4 | 4 OH- + Ptel → O2↑ + H2O + Ptsf | Alkaline oxygen electrolysis | 115 |
| 5 | 2HPO42- + H2O → H3PO4 + O2 | Acidic coal gasification | 319 |
| 6 | C+H2O → CO↑ + H2↑ | Ordinary coal gasification | -153 |
| 9 | 10H+ + 4Cel → C4H10 + 4Csf | Electrolytic coal hydrogenation to butane | -566 |
| 10 | 5H2 + 4Csf → C4H10 + 4Csf | Direct coal hydrogenation to butane | -401 |
| 11 | CO2 liq + H2Oel → CO + OH- | Electrolytic CO2-reduktion | 208 |
| 12 | CO + Fesf → OC-Fesf | CO-chemisorptions | -294 |
| 15 | 4OC-Feel + 14H+ → C4H10 + 4Fesf + 2H2O + O2↑ | Electrolytic butane synthesis | 378 |
| 16 | 4OC-Fecs + 7H2 → C4H10 + H2O + 4Fesf + O2↑ | Catalytic butane synthesis | 755 |
| 19 | 4CO2 + 13H2 → C4H10 + 8 H2O | Direct butane synthesis | -621 |
| 23 | 2H+ + Ptel → H2↑ + Ptsf | Acidic hydrogen electrolysis | -86 |
| 24 | CO + H2 → C + H2O | CO recovery | -83 |
CO Reduction:
CO Reduction + Oxygen recovery:
Conclusion: alkali electrolysis is really better than acid electrolysis (for this purpose)
Energy balance of the calculated processes is only comparable when taking into account also sustainability of oxygen.
Energy demand for electrolytic processes is not principally lower than for thermodynamic processes, but:
e.g. Maybe our developments are too early. Nevertheless: experiments will start soon in the Helio-Synth Lab!
Auswahl des Arbeitsschwerpunktes mit einer Wirtschaftlichkeitsberechnung
ca. 9000 kWh
Auf Wunsch kann kurzfristig auch mit anderen Werten gerechnet werden.
| Wirkungsgrad | |
|---|---|
| Ölbrenner | 90 % |
| Holzbrenner | 90 % |
| Thermieanlage | 60 % |
| Windsystem | 30 % |
| Akku | 90 % |
| PV-System | 10 % |
| Verkohlung |
| Wirkungsgrad | |
|---|---|
| Kohlehydrierung | 80 % |
| Anode | 80 % |
| H2-tank | 90 % |
| COs Wäscher | 75 % |
| CO2 Freisetzen | 80 % |
| CO2 Reduktion | 95 % |
| Mikroreaktor | 75 % |
| Wirkungsgrad | |
|---|---|
| El. Chemische Synthese | 75 % |
| Sonnentage | 150 % |
| Sonnenstunden | 6 % |
| Windtage | 100 % |
| Windstunden | 12 % |
| Akku-Ladezyklen | 1.000 % |
| I-Kohlehydrierung (A/dm2) | 10 % |
| Wirkungsgrad | |
|---|---|
| I-Hydroniumerzeugung (A/dm2) | 3 % |
| I Freisetzung CO2 (A/dm2) | 3 % |
| I Reduktion CO2 (A/dm2) | 3 % |
| I El. Chemische Synthese (A/dm2) | 3 % |
Bild: Volumetric adsorption testing apparatus aus „Hydrogen storage capacity of activated carbon pellet bounded by Lignocellulose liquid“ von Y.Nasrudin, Mahmud Sudibandriyo, Awaludin Martin, Jauhari Ali.
Sprit aus Kohle und solarem Wasserstoff
Neuer Weg: elektrochemisch für kleine Einheiten ist im Versuchsstadium
| solarthermische Anlage | konventionelle, saisonale Speicherung von Warmwasser in einer großen kaverne |
| netzgekoppelte PV | selbsterklärend |
| Insel PV-Anlage (Akkus) | saisonale Speicherung photovoltaischer Energie in Blei-Akkumulatoren |
| kohleaequ. Hydrierung | der Heizölmenge entsprechende Kohle wird mit solarem Wasserstoff zu Brennstoff gemacht |
| brennstoffaequ. Hydrierung | nur so viel Kohle wird hydriert, damit die gegebene Heizölmenge dabei herauskommt |
| PV-Anlage mit Hydridspeicher | eine PV-Anlage erzeugt Wasserstoff, der in einem drucklosen Feststoff-Speicher bei Raumtemperatur gelagert wird |
| CO2-Recycling mit MikR. | CO2 wird in Lauge eingefangen und mit erneuerbarem Strom wieder in Brennstoff rückgeführt |
| teilweise thermisches CO2 Recycling | wie oben, nur das Wieder-Freisetzen des CO2 erfolgt mit Parabolspiegelkollektoren |
| CO2 Recycling mit Elektroaktiver Membran | wie obige zwei Anzätze, nur elektrochemisch mit einer revolutionären Membrantechnologie |
Die Werte sind variabel, weil PV- und Thermieflächen wetterabhängig sind!
1m3 Heizöl enspricht
1.208,6 kg Kohle
4,77 Raummeter Holz
| Art der Energiewirtschaft | kWh elektrisch | m2 Photovoltaik | m2 Thermie | m3 Speicher |
|---|---|---|---|---|
| Solarthermischer Anlage | 0 | 0 | 34 | 128 |
| Netzgekoppelte PV | 8.929 | 124 | 0 | 0 |
| Insel PV-Anlage (Akkus) | 19.412 | 270 | 0 | 59 |
| Kohleaequ. Hydrierung | 4.049 | 56 | 0 | 2 |
| Brennstoffaequ. Hydrierung | 2.128 | 30 | 0 | 1 |
| PV-Anlage mit Hydridspeicher | 9.821 | 137 | 0 | 12 |
| CO2-Recycling mit Thermischem Mikroreaktor | 11.106 | 154 | 0 | 12 |
| Teilweise Thermisches CO2 Recycling | 4.408 | 61 | 19 | 6 |
| CO2 Recycling mit elektroaktiver membran | 9.853 | 127 | 0 | 6 |
Erste experimentelle Ergebnisse der Kohlehydrierung in kleinsten Einheiten durften wir auf der EMR 2017 – The Energy and Materials Research Conference in Lissabon vorstellen.
From the Energy and Materials Research Conference – EMR 2017 in Lisbon (Portugal), 5-7 April 2017
F. Kröner
HELIO-SYNTH e.V., W. Hohenheimstrasse 5, 9500 Villach, Austria
At EMR2012 the author presented theoretical calculations of the subject. Now first experimental results are available.
The purpose of the research is to invent a device for making fuel out of coal. The device shall react very fast to an alternating power source and shall be down scalable to very small units. These are typical demands of renewable electricity generation.
Therefore an electrochemical approach which works near room temperature is going to be developed. The ansatz can be seen as the electrochemical analogue of the Bergius-Pier process.
Physically there are two steps of el ectrochemical reactions. Crushed Coal is switched as the cathode in an electrochemical cell, which anode is a platinum grid. The electrolyte may be any acid.
In a first voltage step protons of the electrolyte are attached with covalent bonds to surface sites of the carbon of the coal particles. This hypothesis is experimentally supported by the fact that when replacing the power supply by a resistor, a current in the opposite direction is observed with a characteristic time which is orders of magnitude higher than the RC constant of the electrochemical cell. It is supposed, although not yet experimentally proven, that a carbon modification with a much higher surface to volume ratio could make a valuable electrolyte-air battery out of the device.
When increasing the applied voltage in a second step, the conductivity of the cell in creases remarkably, which means either hydrogen production occurs or the synthesis of some hydrocarbons takes place. When feeding pulses both in forward and reverse direction it can be demonstrated that carbon containing liquids as reaction products appear, and cathodic hydrogen production can be suppressed. Since there are many degrees of freedom regarding the electronic pulse series, there are also some degrees of freedom in the resulting reaction products of this electrochemical cell.
Chemically it can be explained that low voltages correspond to C-H bonds, which are exothermic, and higher voltages correspond to the dissociation of C-C bonds which is endothermic. With the height and width of the pulses there are some degrees of freedom to synthesize the output molecules.
Patents pending
Keywords: fuel synthesis; electrochemical
