how to generate green hydrogen with the help of renewable energy sources, discussed here

1. Under the supervision of
Prof. (Dr.) Paulson Samuel
By
Raj Kapur Kumar
2021REE09
Department of Electrical Engineering
Motilal Nehru National Institute of Technology
Prayagraj, India
Green Hydrogen Generation

2. CONTENTS
1. Introduction
2.Types of Hydrogen
3.Why Green Hydrogen?
4.Challenges
5.Modelling of PEM Electrolyser
6.Matlab/Simulation
7.Results
8.Conclusion
9.Future Work
10.References
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3. INTRODUCTION
• Green hydrogen is defined as hydrogen produced by splitting water into hydrogen and
oxygen using renewable electricity. This is a very different pathway compared to both
grey and blue.
• Depending on production methods, hydrogen can be grey, blue or green – and
sometimes even pink, yellow or turquoise.
• Grey hydrogen produced from coal with significantly higher CO2 emissions per unit of
hydrogen produced called brown or black hydrogen instead of grey[1].
• Blue hydrogen follows the same process as grey, with the additional technologies
necessary to capture the CO2 produced when hydrogen is split from methane (or from
coal) and store it for long term.
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4. INTRODUCTION
*Steam Methane Reforming (SMR) or coal gas
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5. Why Green Hydrogen ?
• Recent successes of renewable energy technologies and electric vehicles have shown
that policy and technology innovation have the power to build global clean energy.
• Hydrogen is emerging as one of the leading options for storing energy from renewables
other than batteries, flywheel, compressed air, pumped hydro, ultracapacitors, etc.
• UN Climate Conference, COP26, Governments and industry have
both acknowledged hydrogen as an important pillar of a net zero economy[2].
• Green hydrogen is the only type produced in a climate-neutral manner making it critical
to reach net zero by 2050.
• India has set a target to produce 5 million tonnes (mt) of green hydrogen by 2030. Over
the next decade, the government plans to add 175 GW of green hydrogen-based energy.
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6. Challenges
• Rohit Ahuja, head of research and outreach, ICRA said the ambitious plan to boost
green hydrogen production and use would succeed only if the cost of green
hydrogen comes down, which he said would be possible by facilitating cheaper and
mass production of electrolysers.
• Major technical challenges that hydrogen production via water electrolysis:
-Hydrogen cost, EL efficiency, and electricity price
• Current green hydrogen production costs range anywhere between ₹320 and ₹330
per kilogram in India[2].
• Electrolysis for green hydrogen production needs to significantly scale-up and
reduce its cost by at least three times over the next decade or two.
• Green hydrogen costs in India could potentially fall by half to as low as ₹160-170
per kg by 2030.
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7. ELECTROLYZER
• An electrolyzer is defined as an apparatus that separates the water (2H2O) into
hydrogen (2H2) and oxygen (O2)
• Water electrolysis may be classified as a reverse process of hydrogen that is fed into a
Fuel cell.
• There are two types of electrolysis, Alkaline and Proton exchange membrane (PEM),
The PEM cells are known to be reversible devices for hydrogen systems when
compared to alkaline based electrolysis. They also have many advantages like smaller
dimension and mass, lower power consumption, lower operating temperatures [3].
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8. Fig. 1. Schematic representation of PEM EL and PEM FC [6]
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• An electrolyzer electrical circuit can be represented as a voltage sensitive nonlinear
DC load, so that the higher voltage applied is the higher load current is circulating
and the more H2 can be generated [4].
• Empirical/semi-empirical models allow the prediction of the electrolyzer behavior
as a function of operating conditions (such as pressure, temperature) recurring to
simple empirical equations.
• Model of PEM electrolyzer is useful for the analysis of the system behavior, I − V
curve, hydrogen production rate and the efficiency.
ELECTROLYZER ELECTRICAL EQUIVALENT CIRCUIT

10. ELECTROLYZER ELECTRICAL EQUIVALENT CIRCUIT
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Fig. 2. Single cell Equivalent Electrical Model for a PEM electrolyzer[6]

11. MATHEMATICAL REPRESENTATION OF
ELECTROLYZER ELECTRICAL EQUIVALENT CIRCUIT
• In order to obtain the I-V and hydrogen production characteristics, some equations have
been developed for steady state conditions and implemented in MATLAB/Simulink
• Electrolyser Voltage (V) is given as function of Temperature(T) and pressure(P)[6]
• 𝑅𝑖is Initial cell resistance is given as
• 𝑒𝑟𝑒𝑣 (V) Reversible cell potential(Potential difference between anode and cathode)
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R (J/molK) Ideal gas constant
.........(1)
............(2)
F (C/mol) Faraday constant
.............(3)

12. MATHEMATICAL REPRESENTATION OF
ELECTROLYZER ELECTRICAL EQUIVALENT CIRCUIT
• Ideal voltage, Vi , for electrolysis and hydrogen production is defined by equation(4)
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...............(4)
• ∆G(J /mol) represents the Gibbs free energy change of hydrogen gas and is given by
.............(5)
• 𝑽𝑯 Hydrogen production rate (ml/min) can be calculated as a function of I(T , p)
................(6)
where, 𝑽𝒎 is the one molar volume given by the ideal gas expression as:
................(7)

13. ELECTROLYZER MODEL
• In practice, efficiency is calculated as the ratio of reversible voltage (1.48V) to the applied
voltage. It is also evident in the P −η curve that the efficiency decreases in an exponential
manner with the increase in input power
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...............(8)
• Input power to the electrolyzer is calculated as
• The useful power PH2 , which is the electro-chemical hydrogen energy per
second, corresponds to the hydrogen production and is defined as:
.......................(9)
.........(10)

14. • Considered 2V and 1 A PEM Electrolyser as Electrical Load
• PV-Module designed for 5V and 2A
• Buck converter parameters taken from the website for 5V input to 2V Output and 1A
current requirement practical values to matches the simulated results.
• Some of the Mathematical constant for the development of Electrical Equivalent PEM
Electrolyser Model at T=20°𝐶 and P=1 atm is taken from[3][4][6]
• Obtained Results
• Hydrogen Production Rate=7.442(ml/min)
• Efficiency= 68.5%
• Varying the El voltage, power , and Current varying the Hydrogen production Rate
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MATLAB SIMULATION OF PEM ELECTROLYSER
POWERED by SOLAR PV

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Item Value
Irradiance(W/m^2) 1000
Temperature(°𝐶) 25
Voc(V) 6
Isc(A) 2.5
Vmp(V) 5
Imp(A) 2
P(W) 10
R(Vmp/Imp) 2.5 Ohms
PV-Module Parameter
Item Value
Input Voltage(V) 5
Output Voltage(V) 2
Load Current(A) 1
Duty Cycle 36.11
Frequency(KHz) 40
L(𝑢𝐻) 87
C(𝑢F) 29.17
Buck Converter Parameter

16. MATLAB SIMULATION OF HYDROGEN
GENERATION
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17. PV-Module
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18. PV- Parameters
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19. Buck Converter
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PEM ELECTROLYSER MODEL

21. Fig.3. Current Vs Hydrogen Production Plot
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Fig.4 El Voltage Vs Hydrogen Production Plot
Fig.5. Power Vs Hydrogen Production Plot
@T=20°𝐶, 𝑃 = 1𝑎𝑡𝑚

22. Fig.6 PEM electrolyzer polarization curve with the contribution of activation and ohmic losses
• Ecell is the open circuit
voltage
• VAct,a and VAct,c are
the anode and cathode
activation
overpotentials,
• I is the current density
• and Rcell is the
electrolyzer cell
resistance (ohmic
losses)
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23. Fig.7 Current Vs El Voltage Plot
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Fig.8 Power Vs Efficiency Plot
@T=20°𝐶, 𝑃 = 1𝑎𝑡𝑚

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Fig.9 Current Vs El Voltage
P↑ 𝐸𝑙 𝑣 ↑
T↑ 𝐸𝑙 𝑣 ↓

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Fig.10 Power Vs Efficiency
T↑ 𝜂 ↓
P↑ 𝜂 ↓

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Fig.11 Current Vs Hydrogen Production Rate
P↑ 𝐻𝑃 ↓
T↑ 𝐻𝑃 ↑

27. CONCLUSION
• Developed MATLAB simulation model of PEM Electrolyser with the help
of Electrical equivalent circuit of PEM Electrolyser.
• Integration of PV-Module, Buck converter with Electrical equivalent
circuit of 2V and 1A load PEM Electrolyser is designed.
• Different observation has been obtained by varying Temperature,
Pressure, and current.
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28. Future Work
• Paper Writing
• Design of DC-DC Converter and Control For Electrolyser Application
considering
-High energy efficiency
-Low electromagnetic disturbances.
-Reduced cost.
-High voltage ratio.
-Low output current ripple (to extend electrolyser lifespan)
-Ability to operate in case of electrical failure
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29. References
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[1] https://www.fortuneindia.com/macro/green-hydrogen-costs-to-halve-to-160-170-per-kg-by-
2030/107549
[2] 28 companies pledge to accelerate use of decarbonized hydrogen at COP26 - World
Business Council for Sustainable Development (WBCSD)
[3]M. Albarghot and L. Rolland, "MATLAB/Simulink modelling and experimental results of a
PEM electrolyzer powered by a solar panel," 2016 IEEE Electrical Power and Energy
Conference (EPEC), 2016, pp. 1-6, doi: 10.1109/EPEC.2016.7771691.
[4] D.S. Falcão, A.M.F.R. Pinto, A review on PEM electrolyzer modelling: Guidelines for
beginners, Journal of Cleaner Production, Volume 261,2020,121184,ISSN 0959-6526,
https://doi.org/10.1016/j.jclepro.2020.121184
[5] Abdin, Z., Webb, C.J., Gray, E.M., 2015. Modelling and simulation of a proton exchange
membrane (PEM) electrolyser cell. Int. J. Hydrogen Energy 40, 13243e13257
[6] A. Beainy, N. Karami and N. Moubayed, "Simulink model for a PEM electrolyzer based on
an equivalent electrical circuit," International Conference on Renewable Energies for
Developing Countries 2014, 2014, pp. 145-149, doi: 10.1109/REDEC.2014.7038547.

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THANK YOU