The document provides an extensive overview of hydrogen, including its properties, production methods via electrolysis, storage, compression, and potential as a clean energy carrier. It discusses the environmental benefits of hydrogen production and highlights safety concerns and challenges related to its use. Additionally, it mentions the need for technical assistance regarding the feasibility of hydrogen as a cooking fuel in Nepal.

1. -Zubin Shrestha
info@windpowernepal.com

2. Hydrogen facts
 Lightest
 Most abundant
 Colourless
 Odourless
 Non-toxic
 Non-carcinogenic gas
 Not found by itself on Earth but in its
molecular form combined with another
chemical as a compound (e.g. water, methane)

3. How can it be produced?
 Water electrolysis using any power source including wind,
solar, nuclear power
 Gasification of Coal
 As a by-product from reforming natural gas/biogas with steam
 From gas or biomass-derived alcohols

4. Electrolysis
 Using electricity to split water into hydrogen & oxygen
 Reaction takes place in electrolyzers
 Decomposition of water (H2O) into oxygen (O2) and hydrogen
gas (H2) due to an electric current being passed through water

5. Electrolyzers
 Consist of an anode and cathode separated by an electrolyte
producing an electrically conducting solution when dissolved in
water
 Three types of electrolyzers:
 PEM (Polymer Electrolyte Membrane)
 Alkaline
 Solid Oxide
 PEM Electrolyzer:
 Electrolyte is a solid speciality plastic material
 Electrons flow through external circuit and hydrogen ions
selectively move across the PEM to the cathode
 Combine with electrons from external circuit to form hydrogen gas
 Operates at 70°-90°C

6.  Alkaline Electrolyzer:
 Use of liquid alkaline solution of sodium or potassium hydroxide as
the electrolyte
 Transport of hydroxide ions through the electrolyte from cathode
side to anode side
 Operates at 100°-150°C
 Solid Oxide Electrolyzer:
 Use of solid ceramic material as the electrolyte
 Selective conduction of negatively charged oxygen ions at elevated
temperatures
 Operates at much higher temperatures for the functioning of solid
oxide membranes : 700°-800°C

7. The Process
 Hydrogen gas produced at cathode (-ve)
 Reduction reaction with electrons from cathode given to hydrogen
cations
 2H+
(aq) + 2e-  H2 (aq)
 Oxygen gas produced at anode (+ve)
 Oxidation reaction giving electrons to the anode
 2H2O (l)  O2 (g) + 4H+
(aq) + 4e-

8.  Overall Reaction : 2H2O (l)  2H2 (g) + O2 (g)
 Twice the amount of hydrogen molecules produced than
oxygen molecules
 Produced hydrogen gas has twice the volume of the produced
oxygen gas (assuming equal temp. and pressure for both
gases)

9. The Verdict
 Hydrogen production via electrolysis can result in zero
greenhouse gas emissions
 Offers opportunities for synergy with variable power generation
 Allows for flexibility to shift production to best match resource
availability with system operational needs and market factors
 Possibility of the elimination of curtailing excess energy from
renewable energy generation
 Grid electricity is not environmentally friendly, energy intensive,
and is not an ideal source for electricity for electrolysis
 Renewables integrating hydrogen production through
electrolysis is a possible option to overcome these limitations

10. Storage
 Usually stored in a liquid or gas state
 Liquid hydrogen kept at temperatures bordering on -253°C in
highly insulated tanks
 As a compressed gas underground at pressures up to 150 bar
(15MPa)
 Gaseous hydrogen storage is simplest and most extensively
employed for both large and small scale storage

11.  Steel cylinders or special composite material tanks (Li, Mg, C
based) are capable of holding the gas at 700 bar
 Typical storage: < 1.5% wt H2 , >98.5% wt of cylinder
 Increase of % wt of H2: lighter cylinders at higher pressures
 High cost of materials required for storage
 High amount of energy is required to liquefy hydrogen

12. Hydrogen Compression
 Hydrogen gas requires much larger tanks for its storage
compared to hydrocarbons due to its poor energy density by
volume
 As a compressed gas usually at pressures up to 200 bar (3000 psi)
 Increasing gas pressure improves the density by volume, making
for smaller, but heavier container tanks
 Compressed hydrogen storage can exhibit very low permeation
 Special composite material tanks are capable of holding the gas
at 700 bar

13.  Compressed hydrogen is conventionally stored at near-ambient
temperatures
 “Cold” (sub-ambient but >150K) and “Cryogenic” (150K and
below) storage being investigated to achieve higher H2 densities
at reduced temperatures
 Cost of current compressed gas systems is dominated by
composite materials & processing with a significant impact from
balance of plant (BOP) components

14.  Hydrogen compressors increase the pressure on the hydrogen
and can transport it through a pipe
 Approx. 15% of the usable energy from the hydrogen is lost on
compression using today’s compression technologies
 Also reduces the volume of hydrogen gas
 Examples:
 Electrochemical hydrogen compressor
 Hydrogen supplied to the anode
 Compressed hydrogen is collected at the cathode
 Energy efficiency up to and even beyond 80%
 Pressures up to 700 bar
 Linear compressor
 Piston moves along a linear track to compress the working fluid
 Used under cryogenic conditions

15. Utilization
 To provide electricity and heat through its use in fuel cells
 Fuel cells generate electricity from an electrochemical reaction
where oxygen and hydrogen combine to form water
 Electricity produced used in a variety of applications
 Heat produced as a by-product used for heating and cooling
purposes

16. Why Hydrogen?
 A clean energy carrier produced from any primary energy source
 Pros of Hydrogen as an energy carrier:
 Security of Energy Supply
 Air Quality & Health Improvement
 Greenhouse Gas Reduction
 Ensures Economic Competitiveness

17. Hydrogen Safety
 Knowledge gaps have existed for several decades regarding:
 Conditions of ignition
 Flame acceleration
 Structural protection
 Ventilation
 Public perception and confidence in hydrogen relies on
credibility, transparency, and individual benefit

18.  Exhibits wider limits of flammability, high detonation
sensitivity, and relative low ignition energy if mixed with air,
in comparison to conventional fuels

19.  Codes & Standards regarding Hydrogen Safety:
 Safety distances
 Design of buildings & containers for housing hydrogen equipment
 Earthing & lightning protection
 Materials & components used in hydrogen systems

20. Risks & Challenges
 Mixtures of hydrogen in are flammable over a wide range of
compositions
 Energy required to ignite a hydrogen/air mix can be very low
 Burns with a flame that is invisible in daylight
 Small molecule that can leak very easily
 If released and ignited, it burns with a rapidly moving flame

21. Conclusion
 Sophisticated battery for energy
storage
 High potential as a relatively clean
fuel of the future
 Negative net energy i.e. it takes more
energy to produce it than it contains
 Very low calorific value
 Requires larger and heavier fuel
tanks
 Extraction methods are extremely
energy intensive (e.g.. Electrolysis of
water)

22. Thank You
WindPower Nepal is looking for technical assistance to find out if
Hydrogen could be used as a Cooking Fuel in Nepal. For further
information, please write to us at
info@windpowernepal.com