types of hydrogen fuels

1. Types of hydrogen fuels
1. Grey Hydrogen
2. Blue Hydrogen
3. Black and brown hydrogen
4. Turquoise hydrogen
5. Green Hydrogen
6. Pink hydrogen
7. Yellow hydrogen
8. Purple Hydrogen
9. Red Hydrogen
10. White hydrogen

2. Grey hydrogen
• Currently, this is the most
common form of
hydrogen production.
Grey hydrogen is created
from fossil fuels (natural
gas, methane) biogas,
using steam methane
reformation process but
without capturing
the greenhouse
gases made in the
process.

3. Blue hydrogen
• It is also produced in a
same process as grey
hydrogen except by
following the carbon
capture and storage
(CCS).

4. Black and brown hydrogen
• Using black coal or lignite
(brown coal) in the hydrogen-
making process, these black
and brown hydrogen are the
absolute opposite of green
hydrogen in the hydrogen
spectrum and the most
environmentally damaging. In
this method hydrogen is
produced by gasification coal
method.
• If we use black coal hydrogen
produced is called black
hydrogen and if we use brown
colored lignite as a source it’s
called brown hydrogen.

5. Turquoise hydrogen
• Turquoise hydrogen is made
using a process called
methane pyrolysis to
produce hydrogen and solid
carbon.
• In the future, turquoise
hydrogen may be valued as
a low-emission hydrogen,
dependent on the thermal
process being powered with
renewable energy and the
carbon being permanently
stored or used.

6. Pink hydrogen
• Pink hydrogen is
generated through
electrolysis powered by
nuclear energy.

7. Yellow hydrogen
• In this method
hydrogen made through
electrolysis using solar
power.

8. Purple hydrogen
• In this method
hydrogen is made using
nuclear power and heat
as combined form in a
process called
thermochemical water
splitting (High
temperature
electrolysis)

9. Red hydrogen
• Red hydrogen is
produced through the
high-temperature
catalytic splitting of
water using nuclear
power as thermal
energy source.

10. White hydrogen
• It is a naturally
occurring geological
hydrogen found in
underground deposits
and created through
fracking.

11. Green hydrogen
• green hydrogen is the one produced
with no harmful greenhouse gas
emissions.
• Green hydrogen is made by using
clean electricity from surplus
renewable energy sources, such as
solar or wind power, to electrolyse
water.
• Electrolysers use an electrochemical
reaction to split water into its
components of hydrogen and oxygen,
emitting zero-carbon dioxide in the
process.
• Green hydrogen currently makes up
a small percentage of the overall
hydrogen because production is
expensive.

12. Generation of green hydrogen
Green hydrogen is hydrogen produced by splitting water by
electrolysis. This produces only hydrogen and oxygen. We can
use the hydrogen and vent the oxygen to the atmosphere with
no negative impact.
Electrolysis is a promising option for carbon-free hydrogen
production from renewable and nuclear resources. Electrolysis is
the process of using electricity to split water into hydrogen and
oxygen.
This reaction takes place in a unit called an electrolyzer.
Electrolyzers can range in size from small, appliance-size
equipment that is well-suited for small-scale distributed
hydrogen production to large-scale, central production facilities
that could be tied directly to renewable or other non-
greenhouse-gas-emitting forms of electricity production.

13. Working
• Like fuel cells,
electrolyzers consist of an
anode and a cathode
separated by an
electrolyte. Different
electrolyzers function in
different ways, mainly
due to the different type
of electrolyte material
involved and the ionic
species it conducts.
• Diagram:

14. Types of electrolyzers
Polymer Electrolyte Membrane Electrolyzers
Alkaline Electrolyzers
Solid Oxide Electrolyzers

15. Polymer Electrolyte Membrane
Electrolyzers
• In a polymer electrolyte membrane (PEM) electrolyzer, the
electrolyte is a solid specialty plastic material.
• Water reacts at the anode to form oxygen and positively charged
hydrogen ions (protons).
• The electrons flow through an external circuit and the hydrogen
ions selectively move across the PEM to the cathode.
• At the cathode, hydrogen ions combine with electrons from the
external circuit to form hydrogen gas.
Anode Reaction: 2H2O → O2 + 4H+ + 4e-
Cathode Reaction: 4H+ + 4e- → 2H2

16. Alkaline Electrolyzers
• Alkaline electrolyzers operate via transport of
hydroxide ions (OH-) through the electrolyte from the
cathode to the anode with hydrogen being generated
on the cathode side.
• Electrolyzers using a liquid alkaline solution of
sodium or potassium hydroxide as the electrolyte
have been commercially available for many years.
• Newer approaches using solid alkaline exchange
membranes (AEM) as the electrolyte are showing
promise on the lab scale.

17. Solid Oxide Electrolyzers
Solid oxide electrolyzers, which use a solid ceramic material as the electrolyte
that selectively conducts negatively charged oxygen ions (O2-) at elevated
temperatures, generate hydrogen in a slightly different way.
Steam at the cathode combines with electrons from the external circuit to
form hydrogen gas and negatively charged oxygen ions.
The oxygen ions pass through the solid ceramic membrane and react at the
anode to form oxygen gas and generate electrons for the external circuit.
Solid oxide electrolyzers must operate at temperatures high enough for the
solid oxide membranes to function properly (about 700°–800°C, compared to
PEM electrolyzers, which operate at 70°–90°C, and commercial alkaline
electrolyzers, which typically operate at less than 100°C). Advanced lab-scale
solid oxide electrolyzers based on proton-conducting ceramic electrolytes are
showing promise for lowering the operating temperature to 500°–600°C. The
solid oxide electrolyzers can effectively use heat available at these elevated
temperatures (from various sources, including nuclear energy) to decrease
the amount of electrical energy needed to produce hydrogen from water.