Hydrogen Production from Solar Energy .pptx

Green Hydrogen

1. Hydrogen Production from Solar Energy 2022

2. Syllabus Introduction Alkaline Water Electrolysis Other types of electrolyser Modelling and Simulation Photovoltaic System Design Results and Validation Enhancements and Future Trends 2

3. Introduction 3

4. Energy Renewable Energy Non-renewable energy For example, Egypt is willing to increase the share of energy from renewables by 42% in 2035 instead of 20% in 2020. So, the world’s demand for renewable sources will require an innovative solution to store this energy. Most of the countries set a strategy to increase their power sources from renewables. Based on: EU (2015a), “Integrated Sustainable Energy Strategy”; MOP (2015), Sustainable Development Strategy: Egypt Vision 2030; NREA (2013), CREMP 4

5. Energy Mismatch Energy Demand is the consumption of energy by human activity. Energy Supply   is the quantity of energy available that suppliers can provide to end users. Source: Meteonorm 6.0(www.meteonorm.com);uncertainly10% Period:1981-2000; grid cell size: 1 deg. 5

6. The difference between the unpredictable and weather-dependent demand and the weather-dependent supply results in a mismatch in short time periods of hours. Energy storage systems (ESS) can be used to balance electrical energy supply and demand. The process involves converting and storing electrical energy from an available source into another form of energy, which can be converted back into electrical energy when needed. 6

7. Hydrogen Colors 7

8. Alkaline Water Electrolysis & Electrolyzer 8

9. Alkaline Water Electrolysis Electrolysis is the process by which electric current is passed through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron (oxidation or reduction). Alkaline water electrolysis is the decomposition of water into hydrogen and oxygen by passing an electric current (DC) between two electrodes which emersed into Alkaline solution. This reaction takes place in a unit called an Alkaline Water Electrolyzer. 9

10. Alkaline Water Electrolyzer Alkaline Water Electrolyzer Cell Main Components: Electrodes: An electrode is an electrical conductor that makes contact with the nonmetallic circuit parts of a circuit, such as an electrolyte. If in an electrochemical cell, this is also known as an anode or cathode. Material of Electrode: Platinum, Iridium, Nickel, cobalt and iron (stainless steel). Electrolyte: The electrolyte is an aqueous solution which contained either potassium hydroxide (KOH) or sodium hydroxide (NaOH) with a typical concentration of 20 - 40 wt%. 10

11. Alkaline Water Electrolyzer Separating Diaphragm: used to divide the anode and cathode regions to prevent mixing of the evolved hydrogen and oxygen gases while allowing for passage of the electrolyte solution. Commonly used separator materials , which must be corrosion resistant and structurally stable , are woven cloth, polymer materials, oxide ceramic materials like NiO, glass fibers, and porous carbon. 11

12. Other Types of Water Electrolyzers 12

13. Other Types of Water Electrolyzers PEM Solid Oxide 13

14. Alkaline vs PEM vs Solid-Oxide Type Electrolyte Operating Temperature Cell Voltage (V) Materials (Anode-Cathode) Life Time (Years) Manufacturing Cost Production Rate Alkaline KOH 60 – 80 c 1.8 to 2.4 (Platinum, Radium, Nickel, Stainless Steel) Up to 10 Low High PEM solid polymer 50 – 80 C 1.8 to 2.2 (Titanium, Gold, Platinum) 3 - 4 High Low Solid Oxide yttrium zirconium oxides (YZS) 600 – 900 1.48 to 1.52 (Nickel, YSZ, LaMnO3, LaFeO3) 4 - 5 High Low 14

15. Why Alkaline Electrolyzer? 15 Mature. large-scale hydrogen production . Lower Cost . Simple (Design and Fabrication). 03 02 04 01

16. MODELING AND SIMULATION 16

17. Cell Voltage Calculations           17

18. *   Hydrogen Flow calculations 18

19. Results The following figure shows the values of V cell and V rev at wide range of current density at 3 temperatures 19

20. Results The relation between the total consumed power with current density and the effect if the different temperatures on the power 20

21. This graph shows the relation between the hydrogen flowrate with the current density at different 3 temperatures 21 Results

22. This graph shows the effect of the gab between electrodes on Vcell 22 Results

23. Gap Analysis   Where is the gap between cell electrodes i is the current density k the conductivity of electrolyte   23

24. Gap optimum Design 24

25. Foam Concentration Θ is the experimental bubbles on the electrodes. The graph shows critical operation at θ > 0.3 . Foam increases the electrolyte resistance. 25

26. Solar Photovoltaic System-Coupled with Electrolyzer 26

27. Solar Photovoltaic-based Electrolysis This method is based on using electricity produced by PV panels to produce hydrogen by the electrolysis of water. Electrolysis is conducted by passing direct electric current (DC) through the water to generate hydrogen and oxygen. Green house effect The system consists of photovoltaic panel, battery, and a solar charge controller. 27

28. solar panels made of monocrystalline silicon or polysilicon and are most commonly used in conventional surroundings. 28 Types of solar panel

29. Solar irradiance and temperature effect on power, current and voltage Current - voltage and power-voltage curves Temperature dependence , ,   29

30. Charge controller A solar charge controller is available in two different technologies, PWM and MPPT. How they perform in a system is very different from each other. An MPPT charge controller is more expensive than a PWM charge controller, and it is often worth it to pay the extra money. 30

31. Battery Bank Battery is an electrochemical device that converts chemical energy into electrical energy and electrical energy to chemical energy by oxidation-reduction reactions. Classification of batteries based on the depth of discharge Shallow cycle batteries Deep cycle batteries There are two types of batteries that are most used in photovoltaic system: 1-lead acid 2-lithium ion 31

32. THE DESIGN OF THE ALKALINE ELECTROLYSER 32

33. Steps to make the design 33

34. Components of the Alkaline electrolyser 34

35. Components of the Alkaline electrolyser Housing plates For collecting gases For inlet water For fastening 35

36. Components of the Alkaline electrolyser Electrodes Anode Or Cathode Neutral plates 36

37. Components of the Alkaline electrolyser Gaskets For collecting gases For water supply 37

38. Components of the Alkaline electrolyser Separator Pipes Connections Bolt and nuts 38

39. Assembly of the design Design of a Single Cell Alkaline Electrolyser The method of separation the gases 39

40. Assembly of the design The method of connection between cells Monopolar Bipolar Monopolar Bipolar 40

41. Assembly of the design Design of Alkaline Electrolyser Two Stacks Each Stack has Five Cells Connection between cells is Bipolar and between Stack is Monopolar. Every cell needs 2.4 volt. Every Stack needs 12 volt. 41

42. Enchantments And Future Trends 42

43. KEY AREA OF INNOVATION Electrodes & Catalyst Coating Electrolyte & Additives Diaphragm or Separator Materia l Operating pressure and temperature Zero – Gap Configuration 43

44. ELECTRODES & CATALYST COATINGS Material Selection Parameters Over potential Faradic Efficiency Surface Morphology Perforated 0.1 mm is best for H 2 generation & 0.7mm for O 2 Finned, Slotted Better for gas bubbles escape Volcano plot for the hydrogen evolution reaction as a function of the M-H bond strength 44 Source: Zhou, Daojin, et al. "Recent advances in non‐precious metal‐based electrodes for alkaline water electrolysis." ChemNanoMat 6.3 (2020): 336-355.

45. Electron Distribution Molybdenum(MO) & pt alloy electrons are well distributed, better conductivity Electrode doping Increase conductivity & active surface area Nano-Structure Electrode Increase active sites & decrease current density Ruthenium nano-rod cathode was compared to plane ruthenium, 25% decrease in current density & 20% decrease in energy consumption. Treat Electrode Surface Make the electrode surface hydrophilic 45

46. ELECTROLYTE & ADDITIVES Water TDS Electrolyte Circulation Additives: Additives to Reduce Surface tension of bubbles Ionic Liquids ( e.g Dialkylimidazolium ionic liquid) 46

47. Zero Gap Zero-gap configuration consists of minimizing the distance between electrodes. This allows minimizing the voltage drop between the electrodes so the efficiency & performance increased . Efficiency = so as v cell decreases the efficiency increase.   (a) Conventional alkaline cell electrolyser and (b) zero-gap alkaline cell electrolyser. 47

48. Diaphragm or Separator Material The required characteristics of the materials to be used as diaphragms or membranes are: high corrosion resistance in a strongly alkaline medium the possibility of manufacture of porous tissues or porous thin films low ionic resistivity in an alkaline medium in a way which does not decrease the process efficiency Alkaline electrolysers have been equipped in the past with asbestos diaphragms Mg 3 Si 2 O 5 (OH) 4 then the European commission banned the application of asbestos and asbestos related products in 2005 due to serious health hazards . Alternative diaphragm materials are used like Zirfon ® (which is zirconia (ZrO 2 ) embedded in polysulfone (PSF)) but the high price of ZrO 2 forced us to search for another diaghram material . The new cheapest alternatives are barite (BaSO 4 ), forsterite (Mg 2 SiO 4 ) and wollastonite (CaSiO 3 ). The best one is barite (BaSO 4 ) Zirfon Separator Asbestos Separator 48

49. Increasing the operating Temp & Pressure As the operating pressure increases : Volume and size of gas bubbles are reduced Ohmic resistance & ohmic losses reduced Reversible electrolysis voltage increase At constant temperature cell voltage decreases as pressure increase Provides a benefit of being capable of performing high temperature electrolysis. Overvoltage decrease Hydrogen purity is improved Relation between voltage and pressure at constant temp. Source: Li, Yangyang , et al. "Study the effect of lye flow rate, temperature, system pressure and different current density on energy consumption in catalyst test and 500W commercial alkaline water electrolysis."  Materials Today Physics  22 (2022): 100606. 49

50. As the operating temperature increase: Conductivity of electrode, electrolyte, membrane increases efficiency increases Electrical energy consumption to produce hydrogen decreases so the electrical efficiency increases overvoltage & activation voltage decreases The required equilibrium voltage decrease Reaction kinetics at the electrodes improved We can increases the efficiency by increasing the operating pressure and temperature. Equilibrium voltage :the theoretical minimum potential required to dissociate water by electrolysis, below which the electrolysis of water cannot proceed. The equilibrium voltage deceases with increasing temperature. Cell potential for hydrogen production by water electrolysis as a function of temperature. Source: Zeng K, science DZ-P in energy and combustion. Recent progress in alkaline water electrolysis for hydrogen production and applications. Elsevier 2010. https://doi.org/10.1016/j.pecs.2009.11.002. 50