GREEN HYDROGEN PRODUCTION AND STORAGE

VIA NOVEL METHODS

SEMINAR REPORT

submitted by

DISHNA D
TKM21CH028

to

APJ Abdul Kalam Technological University

in partial fulfilment of the requirements for the award of B.Tech Degree in
Chemical Engineering

DEPARTMENT OF CHEMICAL ENGINEERING

TKM COLLEGE OF ENGINEERING, KOLLAM
August, 2024
 DEPARTMENT OF CHEMICAL ENGINEERING
TKM COLLEGE OF ENGINEERING
KOLLAM

CERTIFICATE

Certified that this report entitled ‘GREEN HYDROGEN PRODUCTION AND STORAGE VIA
NOVEL METHODS’ is the report of the seminar presented by DISHNA D,TKM21CH028 during
2023-2024 in partial fulfilment of the requirements for the award of the Degree of Bachelor of
Technology in Chemical Engineering of the APJ Abdul Kalam Technological University.

Dr. Fazil A Mr. Al Ameen A Dr. Fazil A

Guide Seminar Coordinator Head of the Dept.
Associate Professor Assistant Professor Associate Professor
Dept. of Chemical Engg. Dept. of Chemical Engg. Dept. of Chemical Engg.
 DECLARATION
I, Dishna D, Reg. No. TKM21CH028 of Department of Chemical Engineering, TKM College of
Engineering, Kollam hereby declare that I will not publish any of the work conducted as a part of my
B. Tech Degree, in any form (conferences or publications), without the consent of the department.

Place: Kollam DISHNA D

Date : 19/08/24 TKM21CH028

i
 ACKNOWLEDGEMENT

I would like to express my deepest appreciation to all those who have provided me with the
possibility to complete this project. A special gratitude I give to my guide, Dr. Fazil A, whose con-
tribution to stimulating suggestions and encouragement, helped me to coordinate and complete my
seminar. I would like to express my deepest appreciation to all those who have provided me with the
possibility to complete this project. Special gratitude is given to my Seminar Coordinator and Se-
nior advisor Prof.Al Ameen A, whose contribution to stimulating suggestions and encouragement,
helped me to coordinate and complete my seminar.

I show my extreme gratitude to all Faculties and Technical staff members in Chemical Engineering
Dept., for providing all the help and necessary facilities to present this seminar. My deep-hearted
cheers to my parents and all my friends who extended their support and co-operation towards the
successful presentation of the seminar. Last but not the least, I thank Almighty God for his blessings.

DISHNA D
TKM21CH028

ii
 ABSTRACT
Hydrogen economy, which proposes employing hydrogen to replace or supplement the cur-
rent fossil-fuel-based energy economy system, is widely accepted as the future energy scheme for
the sustainable and green development of human society. Hydrogen is a promising clean energy
alternative, but its widespread adoption is hindered by challenges in production and storage. This
study investigates recent advancements in hydrogen production technologies, encompassing anion
exchange membranes, electrified steam methane reforming, and nano-carbon assisted processes. To
fully realize the potential of hydrogen as a clean energy carrier, efficient and cost-effective storage
solutions are imperative. The research explores various storage methods, including cryogenic and
adsorptive methods. In addition to it, an integrated production-storage systems via electrocatalysis
is also discussed. Addressing these technical and economic hurdles is crucial for the successful
transition to a hydrogen-based economy.

Keywords: Anion Exchange Membrane, Electrified Steam Methane Reforming, Adsorption, Solid
oxide electrolysis cell, Green Hydrogen.

iii
 CONTENTS

Declaration i

Acknowledgement ii

Abstract iii

List of Figures vi

List Of Tables vii

Abbreviations viii

1 INTRODUCTION 1

2 LITERATURE REVIEW 3
2.1 Production of Green Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1 Water electrolysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1.1 Low-Temperature water Electrolysis . . . . . . . . . . . . . . . 3
2.1.1.2 High Temperature Steam Electrolysis . . . . . . . . . . . . . . . 5
2.1.2 Steam Methane Reforming . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.1.3 Nano Carbon Assisted Method . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1.3.1 Carbon Nanomaterial for hydrogen production . . . . . . . . . . 8
2.1.3.2 Photo-driven hydrogen production . . . . . . . . . . . . . . . . 9
2.2 Storage of Green Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2.2.0.1 Compression/liquefaction . . . . . . . . . . . . . . . . . . . . . 10
2.2.0.2 Adsorption on Activated Carbon . . . . . . . . . . . . . . . . . 11
2.2.0.3 Silicon and magnesium-based nanomaterials for hydrogen storage 12
2.3 Challenges in hydrogen storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.4 Integration of Green Hydrogen Production and Storage via Electrocatalysis . . . . 15
2.5 Applications of Green Hydrogen . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

3 CONCLUSIONS 18

iv
REFERENCES 19

v
 LIST OF FIGURES

1.1 Demand for global hydrogen by sector under the Net Zero Scenario, 2020–2030.
NZE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.1 A schematic of (a) Alkaline Water Electrolysis (b) AEM (c) PEM . . . . . . . . . 4
2.2 Comparison of SOFC and SOEC operation . . . . . . . . . . . . . . . . . . . . . 6
2.3 A schematic of hydrogen production using SMR . . . . . . . . . . . . . . . . . . 7
2.4 Schematic representation of MEC for biohydrogen production from urine water,
using catalytic cathode based on nanocarbon-coated MoS2 . . . . . . . . . . . . . 9
2.5 Different photon-assisted hydrogen production techniques . . . . . . . . . . . . . 10
2.6 Modes of Hydrogen storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.7 Schematic illustration of (a) traditional hydrogen production and storage and (b)
integration hydrogen production and storage routes. . . . . . . . . . . . . . . . . 16
2.8 Applications of green hydrogen. . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

vi
 LIST OF TABLES

2.1 Merits and Demerits of Hydrogen Storage . . . . . . . . . . . . . . . . . . . . . . 14

vii
 ABBREVIATIONS
1. NZE - Net Zero Emission

2. SOE - Solid Oxide Electrolysis

3. SMR - Steam Methane Reforming

4. AEM - Anion Exchange Membrane

5. HTSE - High Temperature Steam Electrolysis

6. PEM - Proton Exchange Membrane

7. PTPE - Polytetrafluoroethylene

8. SOFC - Solid Oxide Fuel Cells

9. MEC - Microbial Electrolysis Cells

viii
 CHAPTER 1

INTRODUCTION
Hydrogen (H2 ), with its high gravimetric energy density of 33.3 kW h−1 kg−1 , is widely accepted
as one of the most promising alternatives for intermediate energy storage. Unlike conventional
fossil fuel energy sources, the utilization of hydrogen as an energy carrier does not result in the
emission of carbon or other pollutants into the atmosphere. Instead, it produces water as the sole
by product, rendering it an environmentally friendly and sustainable energy option for the future.
The feasibility of transitioning to a hydrogen economy hinges on addressing various current en-
ergy challenges, including the continued reliance on fossil fuels, the urgency of combating climate
change, and ensuring the availability of sustainable energy supplies. However, it should be noted
here that hydrogen gas is not naturally abundant and is commonly produced from other energy
sources, primarily through processes such as steam reforming. To ultimately reach the green hydro-
gen economy, hydrogen should be generated in a green and sustainable manner. However, the clean,
widespread use of hydrogen in global energy transitions faces several challenges, including the slow
development of hydrogen infrastructure, preventing widespread adoption. Moreover, producing hy-
drogen from low-carbon energy is prohibitively expensive, and hydrogen is almost entirely supplied
by natural gas and coal. Currently, regulations are impeding the development of a clean hydrogen
industry. Nonetheless, efforts have been made by several industries and companies to implement
green hydrogen in their products. Green hydrogen is rising and will be the future’s high-demand re-
newable energy. The awareness of the importance of green hydrogen has led to greener technology
and acceptance worldwide. Moreover, hydrogen production from renewable power in a power-to-
gas process may become more cost-effective due to the recent sharp decline in renewable energy
costs. Hydrogen technology showed remarkable resiliency during the COVID-19 pandemic, and
its momentum continues. With ten governments worldwide embracing hydrogen policies, it was a
record year in the year 2020 for low-carbon hydrogen generation and policy action. Fig. 1.1 shows
the demand for the global hydrogen sector in 2020, with refining accounting for 37.18 Mt and the
hydrogen industry accounting for 51.30 Mt. It is projected that by 2025– 2030, there will be a rise
in demand for grid injection (23.85–51.70 Mt), hydrogen for buildings (2.25–5.64 Mt), synfuels
(1.10–7.28 Mt), transportation (2.12–8.55 Mt), and ammonia fuel (7.53–18.11 Mt), on top of the
rise in hydrogen industry (63.22 Mt) but a downfall in refining (33.82 Mt). By 2030, it is also ex-

1
Figure 1.1: Demand for global hydrogen by sector under the Net Zero Scenario, 2020–2030. NZE
[1]
.

pected that there will be a demand for hydrogen in the power industry, which accounts for 18.50 Mt.
This development, however, falls well short of what is required in the Net Zero Emissions by 2050
Scenario. Furthermore, the demand for innovative uses of low-carbon hydrogen remains confined
to road transportation. As a result, extra efforts are required to create the need and reduce emissions
related to producing hydrogen [1] . This report has covered various green hydrogen production
methods like, ESMR, AEM, Nano carbon assisted method. In addition to it integrated production
and storage of hydrogen via electro catalysis is discussed. Novel storage methods like adsorption
on activated carbon,silicon and magnesium based nanomaterials are discussed.

2
 CHAPTER 2

LITERATURE REVIEW
Hydrogen is the most common element in the universe. However, it only occurs in very small
amounts in the Earth’s atmosphere, at around 500 parts per billion (or 0.5 ppm). Apart from traces
of gaseous dihydrogen (H2 ) at the surface and above, we find hydrogen essentially bound to oxy-
gen in water (H2 O) and carbon in all hydrocarbons (CH4 , C2 H6 ). However, over time it became
increasingly clear that several phenomena lead to the continuous production of H2 in the earth’s
crust [2].

2.1 Production of Green Hydrogen

Recent advancement in green hydrogen production technologies include SOEC, AEM, ESMR, nano
carbon assisted method etc.

2.1.1 Water electrolysis

Generally, water electrolysis can be divided into three categories according to the operating tempera-
ture: low-temperature, intermediate-temperature, and high-temperature electrolysis. Low-tempera-
ture, intermediate-temperature, and high-temperature electrolysis usually operate at temperatures
lower than 300°C, in the range of 300–700°C, and higher than 700°C (below 1000°C), respectively.
In addition to the conventional water electrolysis process, other low-temperature water electroly-
sis technologies include alkaline water electrolysis, PEM water electrolysis, and anion exchange
membrane (AEM) water electrolysis [3].

2.1.1.1 Low-Temperature water Electrolysis

Alkaline water electrolysis (Fig 2.1 a) is a well-established, low-cost, the most developed elec-
trolysis method that uses non-noble catalysts. In this process, water splits at the cathode side and
produces hydrogen and OH ions, followed by the OH ions travelling to the anode side to produce
oxygen and water. The electrodes are submerged in the electrolyte, and a diaphragm, which is per-
meable to water and OH ions, separates the product gases . The liquid electrolyte in this process is
usually KOH or NaOH. The electrode can be either nickel, iron, cobalt, Ni-S-Co, La 0.5Sr 0.5CoO3 ,
Ni50% Al, Ni73% W25%, Ni-Fe-Mo-Zn, porous Co, RuO2 , Raney-Ni-Mo, etc. However, the most
widely used electrode is nickel due to its low cost, availability, and high activity. The diaphragm can

3
 Figure 2.1: A schematic of (a) Alkaline Water Electrolysis (b) AEM (c) PEM [3]

be porous oxides (such as Ni, NiO, BaTiO3 , SrTiO3 , etc.) or polymer composites (such as radiation-
grafted PTFE, PTFE-ZrO2 , polyantimonic acid-PTFE, etc.) . Addressing some challenges, such as
carbonate formation, low current density, low dynamic operation, and low purity of gases, can help
further the development of this process. Nickel is a common electrode, and the most commonly used
electrolytes in this process are potassium hydroxide and sodium hydroxide. Alkaline water elec-
trolysis operates in the temperature range of 20–90°C . Although this technology has already been
commercialised, it still suffers from corrosive electrolyte materials, gas crossover, low efficiency,
low current density, etc.

4
 Anion Exchange Membrane (AEM) water electrolysis (Fig2.1 b) is a technology that splits
water into hydrogen and oxygen using an anion exchange membrane, which transports OH− anions
instead of H+ protons. This technology has several advantages over alkaline and PEM cells, in-
cluding no carbonate precipitation, lower ohmic loss, and less expensive raw materials. AEM water
electrolysis operates at low electrolyte concentrations and temperatures between 20-60°C, with var-
ious materials used for the cathode and anode. Despite its advantages, further research is needed to
improve its efficiency and durability. In contrast, PEM electrolysis (Fig 2.1 c) splits water into H+ ,
O2 , and e− at the anode, with H+ traveling to the cathode through the membrane and recombining
with electrons to produce hydrogen. PEM electrolysis offers high energy efficiency, fast response,
and high hydrogen purity but suffers from high material costs and acidic environment.

A comparison of AEM, alkaline, and PEM water-splitting technologies reveals that AEM is
still in the lab-scale stage, while alkaline and PEM have been commercialized but require further
progress to address challenges. Low-temperature processes like AEM and PEM offer facile opera-
tion, compact design, and higher technology readiness levels, but high-temperature water electroly-
sis is more efficient due to decreased internal resistance losses and improved reaction kinetics. The
choice of technology depends on the desired application, with AEM showing promise for its advan-
tages and PEM offering high efficiency and purity. Further research and development are needed to
overcome the drawbacks of each technology and improve their overall performance [3].

2.1.1.2 High Temperature Steam Electrolysis

High-temperature water electrolysis (HTSE) offers a promising avenue for efficient hydrogen pro-
duction. By operating at elevated temperatures (500-900°C), this technology significantly reduces
electricity consumption compared to traditional electrolysis methods. The higher operating tem-
perature enhances reaction kinetics, allowing for more efficient water splitting. Moreover, HTSE
boasts higher overall energy conversion efficiency, with the potential to reach 50% at 900°C. This is
a substantial improvement over conventional electrolysis, which typically loses a portion of energy
as heat. However, HTSE faces challenges, primarily centered around material durability. The harsh
operating environment accelerates cell degradation, hindering its commercial viability. Developing
materials that can withstand these extreme conditions while maintaining optimal performance is
crucial for the advancement of HTSE.
Solid oxide electrolysis (SOE) of steam is a well-known high-temperature electrochemical process.
SOEs can electrochemically produce hydrogen and are usually comprised of an anode for oxygen
generation by an electric potential of around 1.3 V, a cathode for hydrogen generation (or in some

5
 Figure 2.2: Comparison of SOFC and SOEC operation [3]

cases, CO2 electro-reduction), and an oxygen-conducting electrolyte . Similar to the other electrol-
ysis technologies, steam splits into H2 and O2 at the interface between the hydrogen electrode and
electrolyte. Then, oxygen ions transfer to the anode side through the electrolyte and recombine at
the interface between the oxygen electrode and electrolyte to produce oxygen gas. The operation
of SOEC is the reverse operation of SOFC (Fig 2.2) . Solid oxide electrolysis is a developing tech-
nology that benefits from its high efficiency, and the most commonly used catalysts are non-noble
materials. The electrolyte is usually a ceramic material, and a composite of yttria-stabilised zirconia
(YSZ) or Ni-based cermets are the most widely used electrode materials. Half-cell reactions in a
solid oxide water electrolyser at the cathode side (hydrogen evolution reaction (HER) or cathode
half-cell reaction) and the anode side (oxygen evolution reaction (OER) or anode half-cell reaction)
are as follows: Anode side : 2O2 → O2 (g) + 4e

Cathode side : 2H2 O(g) + 4e → 2H2 (g) + 2O2

Overall reaction : 2H2 O(g) → O2 (g) + 2 H2 (g)

6
 Figure 2.3: A schematic of hydrogen production using SMR [3]

Despite its technical hurdles, HTSE remains an attractive option for clean hydrogen produc-
tion. Its potential for higher efficiency and reduced electricity demand make it a compelling tech-
nology to pursue. Continued research and development focused on materials science and cell design
are essential to overcome the existing obstacles and unlock the full potential of high-temperature
water electrolysis.

2.1.2 Steam Methane Reforming

Fossil fuel-based technologies are the most industrial processes for hydrogen generation, among
which steam methane reforming (SMR) is the most widely used route, with a high conversion
efficiency of about 75–85%, which decreases by 5–14% when integrated with a carbon capture
system. The primary feedstock of the SMR process is natural gas, but it should be de-sulphurised
and reformed at about 700–825°C using active carbon. Fig 2.3 explains process of converting
methane to hydrogen, in this process is based on using heat and pressure in which methane reacts
with steam to produce a mixture of hydrogen and carbon monoxide (syngas). Then hydrogen can
be separated from carbon monoxide by passing the mixture through a water-gas shift reactor, and
the final step is the removal of other impurities such as water, methane, carbon dioxide, and the
remaining carbon monoxide.

7
 In order to facilitate the reforming process, some catalysts, such as Ni-based catalysts, transi-
tion metals (such as Cu, Fe, Co, Ni, etc.), noble metals (such as Ru, Pt, Ir, etc.), and oxide supports
(such as Ru/Mg(Al)O, Ni/MgO, Ni.Al2 O3 , etc.), have been used amongst which Ni-based catalysts
are the most widely used materials due to their cost-efficiency and high performance. The existing
infrastructure and relatively high efficiency (74–85%) of this technology are the most important
advantages of this process, but unstable supply and the production of carbon monoxide and carbon
dioxide are the most significant drawbacks of it.

2.1.3 Nano Carbon Assisted Method

Carbon nanomaterials are now conquering many application fields owing to their exceptional prop-
erties like nontoxicity, large active surface area, stability, environmental friendliness, photosensitiv-
ity, and electrical conductivity. In the arena of hydrogen production too, nanocarbons have already
established their presence in major as well as supporting roles. Various forms of carbon, stainless
steel, palladium, nickel alloys, and polyaniline have been reported as efficient cathode and anode
materials for hydrogen production.

2.1.3.1 Carbon Nanomaterial for hydrogen production

Biohydrogen, a clean and renewable energy carrier, can be produced from organic matter through
various biological processes. These processes, including photolysis, fermentation, and CO gas fer-
mentation, harness the capabilities of microorganisms such as algae and bacteria. To enhance hy-
drogen production, researchers have incorporated carbon nanomaterials into these systems. These
nanomaterials offer advantages like increased surface area, improved electrical conductivity, and
catalytic properties, which collectively boost the efficiency of biohydrogen generation. By opti-
mizing these nanomaterials and integrating them into bioreactors, scientists are working towards
developing sustainable and economically viable methods for producing biohydrogen on a larger
scale [4]. Figure 2.4 demonstrates a cost-effective approach to hydrogen production using a micro-
bial electrolysis cell (MEC) with a catalytic cathode coated with a MoS2 -nanocarbon composite.
The incorporation of nanocarbon enhances the conductivity of MoS2 , allowing it to function more
effectively as a catalyst. This design outperforms traditional platinum-based cathodes, producing
more hydrogen. Additionally, synthesized MoS2 -Cu-rGO composites for use as a carbon-based
cathode in a single-chamber MEC for biohydrogen production. The rGO component facilitates sta-
ble bonding with MoS2 , boosting electron transfer and catalytic effects. However, the presence of
negatively charged functional groups causes MoS2 agglomeration, which is resolved by the addition
of Cu2 O. The resulting cathode exhibits excellent stability and cost-effectiveness, achieving a hy-

8
Figure 2.4: Schematic representation of MEC for biohydrogen production from urine water, using
catalytic cathode based on nanocarbon-coated MoS2 [4]

drogen production rate of 0.449 ± 0.027 m3 H2 /m3 d, surpassing reported values for platinum-based
cathodes.

2.1.3.2 Photo-driven hydrogen production

Photons obtained from the Sun are the most abundant and clean energy that is now being widely
explored to quench the energy requirements of the world. Light can be converted into energy, and
further, it can be used for production of next generation fuels like hydrogen. Fig. 2.5 depicts the
different hydrogen production techniques that are aided by photons [4].

Photocatalysis or photocatalytic water splitting uses a semiconducting photocatalyst that can

absorb light and produce electron-hole pairs that carry forward the oxidation reduction reactions. In
photo-electrochemical water splitting, an electrochemical cell with photosensitive electrodes runs
the oxidation-reduction mechanism with the help of an external bias to split water into oxygen and
hydrogen. When photovoltaic cells are used to drive the water splitting in an electrochemical cell,
the mechanism can be termed photovoltaic-electrochemical water splitting. The solar thermochem-
ical hydrogen production technique uses highly concentrated light rays from the Sun to generate the
heat required to take the hydrogen production reaction forward. Photothermal hydrogen production
uses both photons and heat to create the proper reaction conditions, whereas hydrogen production
by photo-assisted microbial treatment of biomaterials comes under the category of photo-biological
methods. Carbon nanomaterials, which are drastically explored due to their exemplary features like
high surface area, low toxicity, and stability, have proven to be excellent co-catalysts and supporting
materials in photo-driven hydrogen production technologies.

9
 Figure 2.5: Different photon-assisted hydrogen production techniques[4]

2.2 Storage of Green Hydrogen

Hydrogen storage technologies encompass both physical and chemical approaches.Fig 2.6 depicts
different modes of hydrogen storage. Physical storage involves compressing hydrogen gas into
high-pressure cylinders (up to 700 bar) or storing it as cryogenic liquid in insulated tanks. While
compressed gas offers simplicity and quick filling, cryogenic liquids provide high energy density but
require insulation to prevent boil-off losses. Chemical storage relies on compounds that form cova-
lent bonds with hydrogen. Complex metal hydrides (such as LiBH4 ) are lightweight and compact,
while metal borohydrides exhibit varying capacities. Additionally, hydrogen-rich ionic liquids can
serve as storage media. The choice of method depends on factors like energy density requirements
and boil-off considerations.

2.2.0.1 Compression/liquefaction
Compression: Compression is the process of increasing the pressure of a gas while reducing its
volume. It serves various purposes across industries. In refrigeration and air conditioning systems,
compressors raise the pressure of refrigerant gases, allowing them to absorb heat from the surround-
ings and cool down. Similarly, in natural gas pipelines, compressors maintain the flow by boosting
the pressure. The Linde process, used for air liquefaction, involves alternating compression, cool-
ing, and expansion stages. By compressing air, its molecules slow down and occupy less space,
facilitating the transition to a liquid state. Turboexpanders, which combine compression and expan-
sion, play a crucial role in achieving efficient liquefaction.

10
 Figure 2.6: Modes of Hydrogen storage.[5]

Liquefaction: Liquefaction converts a gas into a liquid by condensing it. The process requires
precise control of temperature and pressure. Some gases liquefy easily through simple cooling
(e.g., nitrogen), while others need pressurization (e.g., carbon dioxide). Applications include stor-
ing liquefied petroleum gas (LPG), medical procedures using liquid nitrogen (cryosurgery), and
industrial processes (e.g., liquefied chlorine for water purification). Nobel Prize-winning work in-
cludes the liquefaction of helium (4 He) and the discovery of superfluid properties at extremely low
temperatures. Large-scale liquefied natural gas (LNG) production follows a similar process, where
refrigerant gases cool and condense natural gas for storage and transportation.

2.2.0.2 Adsorption on Activated Carbon

Activated carbon, often referred to as activated charcoal, belongs to a class of amorphous carbona-
ceous materials characterized by large porosity and internal surface area. It is derived from various
sources, including coconut shells, coal, and wood. AC serves as an exceptionally effective adsor-
bent due to its unique features [5].
AC adsorbs molecules through various forces, including:

• London Dispersion Forces (van der Waals Forces): These short-range forces depend on the
distance between the adsorbate molecule and the carbon surface. They are cumulative and
additive, resulting in strong physical adsorption

Rice husks and other biomass sources have also been explored for hydrogen storage applications.
By activating these materials with chemicals like KOH, researchers have produced activated carbons
with high surface areas and pore volumes, crucial for hydrogen adsorption. The size and distribution

11
of pores significantly influence hydrogen storage capacity. While these materials show promise at
low temperatures, achieving substantial hydrogen uptake at near-room temperatures remains a chal-
lenge. Recent research focuses on optimizing pore structure and incorporating functional groups to
enhance hydrogen adsorption. Despite advancements, achieving high hydrogen storage capacity at
ambient conditions requires further investigation into pore size distribution, surface chemistry, and
the development of novel activation methods

2.2.0.3 Silicon and magnesium-based nanomaterials for hydrogen storage

Silicon, a versatile material, has gained significant attention for its potential in semiconductor de-
vices. Its non-crystalline and polycrystalline forms exhibit a strong affinity for hydrogen, making
them promising candidates for hydrogen storage. Beyond their electronic properties, silicon-derived
nanostructures like nanowires and porous quantum dots possess unique geometric, photonic, elec-
tromagnetic, and thermodynamic characteristics. To address the critical need for room-temperature
hydrogen storage, researchers have explored the use of diatom frustules as a silicon source to create
a novel nanomaterial capable of storing approximately 5% hydrogen at ambient conditions. This
material involves encapsulating graphene plates within silica micropores, creating a nano-matrix.
Further enhancements were achieved by incorporating a stable palladium-cobalt alloy into the nano-
matrix, resulting in a material with a high surface area and pore volume [5].

• Metal-Decorated Porous Silicon

To optimize hydrogen adsorption, researchers investigated the effects of various metals on porous
silicon. Lithium and palladium demonstrated strong bonding to the pore structure, capable of ad-
sorbing multiple hydrogen molecules. In contrast, beryllium exhibited weaker adsorption proper-
ties. These findings suggest that the metal’s ability to chemisorb hydrogen is crucial for enhancing
overall hydrogen storage capacity. To further improve hydrogen adsorption, researchers explored
the use of an electromagnetic field to attract metal atoms to the surface, leading to surface passiva-
tion and increased chemisorption. Among the tested metals, lithium emerged as the most promising
due to its strong bonding, higher adsorption energies, and favorable atomic weight.

• Silicon Carbide and Metal Decoration.

Density functional theory was employed to investigate the potential of silicon carbide as a hydrogen
storage material. By decorating the silicon carbide surface with lithium, sodium, or magnesium
atoms, researchers achieved a significant increase in hydrogen adsorption capacity. The strong
electronegativity difference between the metal and silicon carbide created an electrostatic charge,

12
enhancing hydrogen molecule stability and binding affinity. These metal-decorated silicon carbide
materials demonstrated impressive hydrogen storage capacities, with lithium-decorated silicon car-
bide exhibiting the highest performance.

• Porous Silicon and Hydrogen Storage Kinetics.

Porous silicon has shown great promise for hydrogen storage due to its ability to interfacially trap
hydrogen. This material can be easily produced through an electrochemical etching process and
releases hydrogen gas when heated. To improve hydrogen desorption and recharge, researchers
focused on developing suitable catalysts for the pore mouths. By studying the kinetics of hydrogen
storage and release, including dissociation, spillover, and bond jumping mechanisms, researchers
determined activation energies and vibrational frequencies. These findings enabled the evaluation of
catalytically modified porous silicon as a hydrogen storage material, demonstrating rapid recharge
capabilities under specific conditions.

• Magnesium-Based Hydrogen Storage.

In addition to silicon, magnesium-based materials have attracted attention for hydrogen storage
due to their abundance, high uptake capacity, and non-toxicity. To enhance magnesium’s hydrogen
storage properties, researchers developed a method to grow carbon materials in situ with magne-
sium hydride nanoparticles. Using coconut shell charcoal as a template, they successfully created
a composite material with improved hydrogen storage characteristics. Another approach involved
producing titanium carbide through argon plasma treatment, which demonstrated potential for hy-
drogen storage but required further optimization due to titanium’s evaporation challenges.

2.3 Challenges in hydrogen storage

Storing hydrogen gas at atmospheric pressure is impractical due to its extremely low volumetric
density. Currently, high-pressure composite vessels are the most advanced technology, capable of
withstanding pressures up to 70 MPa. However, even at these high pressures, volumetric storage
density remains a significant challenge. Further increasing pressure offers minimal benefits while
posing additional technical difficulties. These composite vessels consist of multiple layers including
a hydrogen-impermeable inner liner, a pressure-resistant carbon fiber shell, and an outer protective
layer. Due to packaging constraints, cylindrical vessels with hemispherical ends are typically used
for automotive applications.

Storing hydrogen in liquid form presents its own set of challenges. To maintain liquid hy-

13
 Table 2.1: Merits and Demerits of Hydrogen Storage
Methods Merits Demerits Reference
Liquifaction A high level of purity.There is no In the process of liquefaction, about [6]
need to dehydrogenate and purify 15% of the hydrogen’s energy is
this fuel. consumed.Stores poorly for long
periods of time and hydrogen is lost
through evaporation.Regulation of boil
off is needed. Liquid leakage risk.
Adsorption 23% reduction in hydrogen High energy cost.Technical issues in [7]
storage volume with compression temperature regulation.Majority of
at 20 MPa and 298 K.Due to its adsorbents are poor thermal
exothermic nature, this process is conductors.
favored by low temperatures and
high pressure.Adsorbent is
relatively cheap.
Porous silicon Faster uptake kinetics.Storage Prone to surface oxidation. Low [8]
capacity is greater than 5 wt% in desorption volume.Weak reversibility.
most cases.
Cryogenic Energy density of hydrogen is Extremely low operating temperature. [9]
compression exceptional. An efficient A technical challenge lies in managing
volumetric system. Enhanced thermal conditions.
gravimetric measurement
capability.

14
drogen, specialized tanks with vacuum insulation and radiation shields are required to minimize
heat influx. While technically feasible, these tanks are expensive to manufacture. Additionally, the
energy-intensive liquefaction process reduces the overall efficiency of the hydrogen energy system.
Although liquefaction can be integrated into larger systems, its energy consumption remains a con-
cern. Furthermore, the infrastructure for delivering or producing liquid hydrogen at filling stations
needs to be established.

Hydrogen adsorption on porous carbon is inefficient at room temperature due to its low ad-
sorption enthalpy. While large amounts of hydrogen can be stored at cryogenic temperatures, this
approach is impractical for most applications. Hydrogen’s unique properties, such as lack of charge,
dipole moment, and weak polarizability, contribute to its poor interaction with solid surfaces. Metal
hydrides offer another potential storage method, but most hydrides have unsuitable decomposition
temperatures or insufficient storage capacity. Moreover, the process of releasing hydrogen from
metal hydrides is complex and often requires additional energy and resources. Additionally, metal
hydride particles tend to degrade over time, affecting their performance [5]
The high cost of hydrogen storage is a major barrier to its widespread adoption. For compressed
hydrogen, the cost is primarily driven by the pressure vessels, with higher pressures leading to sig-
nificantly higher costs. Liquid hydrogen storage also incurs substantial expenses due to the required
infrastructure and energy-intensive liquefaction process. Metal hydrides present varying costs de-
pending on the specific material and storage capacity. Overall, reducing the cost of hydrogen storage
is crucial for achieving economic viability and widespread adoption of hydrogen as a fuel. Certain
merits and demerits of hydrogen storage techniques are discussed in Table 2.1

2.4 Integration of Green Hydrogen Production and Storage via

Electrocatalysis
The integration of green hydrogen production and storage through electrocatalysis for direct pro-
duction of chemical hydrogen storage media has emerged as a potential solution to these challenges.
Fig 2.7(a) depicts the traditional hydrogen production and storage . Specifically, through electro-
catalysis, CO2 and H2 O can be converted into methanol or formic acid, while N2 or NOx along
with H2 O can be transformed into ammonia, streamlining the hydrogen economy scheme. In this
perspective, we provide an overview of recent developments in this technology.

Recently, there has been growing interest in chemical hydrogen storage using liquid chemi-
cals such as methanol, formic acid, and liquid ammonia (Fig2.7 b) . These materials offer signifi-

15
Figure 2.7: Schematic illustration of (a) traditional hydrogen production and storage and (b) inte-
gration hydrogen production and storage routes. [10]

cantly higher volumetric hydrogen storage capacity compared to pressurized hydrogen (methanol:
99 kg/m3 , formic acid: 53 kg/m3 , liquid ammonia: 121 kg/m3 ). Importantly, these storage medi-
ums can exist in the liquid phase at relatively moderate temperatures. For example, methanol and
formic acid are liquid at room temperature, while ammonia can be in the liquid phase at 33.5°C.
In practical applications, hydrogen can be released from these storage mediums on-demand. How-
ever, the current industrial production of these chemicals requires extensive energy input, leading
to economic and environmental concerns. Fortunately, recent advancements in electrocatalysis of-
fer a versatile platform for preparing these chemicals sustainably. Through electrocatalysis, CO2
and H2 O can be converted into methanol or formic acid, while N2 or NOx along with H2 Ocan be
transformed into ammonia. In essence, electrocatalysis enables the integration of green hydrogen
production and storage to chemical storage. This process is conducted in an electrolyser with a sim-
ple structure and a low cost. Moreover, green electricity is the sole energy source that powers the
process. Thus, the proposed system is eco-friendly, cost-effective, and easily constructed compared
to the two-step strategy. The emergence of these strategies is expected to catalyse a paradigm shift
in the current energy system, facilitating the transition toward a sustainable hydrogen economy.

16
2.5 Applications of Green Hydrogen
Hydrogen is a versatile energy carrier with a wide range of applications. It is extensively used in
industrial processes like petroleum refining, metal treatment, fertilizer production, and food pro-
cessing. The aerospace industry has a long history of utilizing hydrogen, particularly in rocket
propulsion and as a power source for spacecraft.

Figure 2.8: Applications of green hydrogen. [1]

Fig 2.8 shows that hydrogen can be used in many applications, such as for exploring outer
space, industrial processes, electricity, and vehicles. Hydrogen blending also plays a crucial role by
allowing for the controlled mixing of hydrogen with other gases, optimising energy efficiency and
reducing GHG emissions across various sectors, from transportation to industrial processes.While
the oil refining sector remains the primary consumer of hydrogen, recent years have witnessed a
growing interest in green hydrogen production. This renewable energy source holds immense po-
tential for various sectors, including electricity generation, transportation, and industrial manufac-
turing. Despite the recent dominance of battery electric vehicles, companies like Toyota and Honda
continue to invest in hydrogen fuel cell vehicles, demonstrating the potential for this technology in
the future of clean transportation.

17
 CHAPTER 3

CONCLUSIONS
The concept of a hydrogen economy represents a promising pathway toward a sustainable and
clean energy future for human society, facilitating the transition from fossil fuels to renewable en-
ergy sources. Within this framework, the production and storage of hydrogen play pivotal roles,
shaping the feasibility of the hydrogen economy.In this report we discuss various methods of pro-
duction and storage of hydrogen.For hydrogen production, nano carbon assisted methods, anion
exchange membranes (AEMs), and electrified steam methane reforming . It advocates for further
research on cost-effective and durable materials, particularly focusing on non-noble metal catalysts
and alternative water sources.Electrocatalysis emerges as a promising strategy to integrate hydrogen
production and storage through chemical storage media like methanol, formic acid, and ammonia.
This approach leverages renewable energy sources and simplifies the storage process.Regarding hy-
drogen storage,novel techniques like cryo-compressed containers and biomass-derived porous car-
bons. Research efforts are underway to optimize their performance and cost effectiveness.Finally,
the report highlights the potential of silicon and magnesium-based nanomaterials for high-capacity
room-temperature hydrogen storage. Further research is needed to enhance their stability and op-
timize their performance for practical applications.The future of a clean and sustainable hydrogen
economy likely lies in a combination of these methods, tailored to specific applications. Contin-
ued research and development efforts are crucial to overcome the challenges and unlock the full
potential of hydrogen as a clean energy carrier.

18
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