Different types of fuel cell- 1.Polymer electrolyte membrane (PEM) fuel cells 2.Direct methanol fuel cells Alkaline fuel cells 3.Phosphoric acid fuel cells 4.Molten carbonate fuel cells 5.Solid oxide fuel cells 6.Reversible fuel cells. Modern applications of fuel cell and its use in automobile industries

1. Fuel cell
Chemistry Digital Assignment
Vinit Shahdeo
15BIT0335

2. What is Fuel Cell..???
A fuel cell produces electricity through a chemical reaction, but
without combustion. It converts hydrogen and oxygen into water,
and in the process also creates electricity. It’s an electro-chemical
energy conversion device that produces electricity, water, and
heat.
Fuel cells operates much like a battery, except they don’t require
electrical recharging. A battery stores all of its chemicals inside
and coverts the chemicals into electricity. Once those chemicals
run out, the battery dies. A fuel cell, on the other hand, receives
the chemicals it uses from the outside; therefore, it won’t run out.
Fuel cells can generate power almost indefinitely, as long as they
have fuel to use.
The reactions that produce electricity happen at the electrodes.
Every fuel cell has two electrodes, one positive, called the anode,
and one negative, called the cathode. These are separated by an
electrolyte barrier. Fuel goes to the anode side, while oxygen (or
just air) goes to the cathode side. When both of these chemicals
hit the electrolyte barrier, they react, split off their electrons, and
create an electric current. A chemical catalyst speeds up the
reactions.

3. How does Fuel Cells
Work..???
 Hydrogen molecules are delivered to the anode side of the
fuel cell.
 Electrons are stripped from the molecules and forced to
travel through a circuit, producing electricity.
 The leftover protons pass through the fuel cell and are
recombined with the lost electrons on the cathode side,
producing water molecules.

4. Working of Fuel Cell
• Pressurized hydrogen gas (H2) enters cell on anode side.
• Gas is forced through catalyst by pressure.
• When H2 molecule comes contacts platinum catalyst, it
splits into two H+ ions and two electrons (e-).
• Electrons are conducted through the anode
• Make their way through the external circuit (doing
useful work such as turning a motor) and return to the
cathode side of the fuel cell.
• On the cathode side, oxygen gas (O2) is forced through the
catalyst
• Forms two oxygen atoms, each with a strong negative
charge.
• Negative charge attracts the two H+ ions through the
membrane,
• Combine with an oxygen atom and two electrons from
the external circuit to form a water molecule (H2O).

5. Fuel Cells Vs Conventional
Power Sources
FC is an electrochemical device in which the energy of fuel and
oxidant continuously supplied to electrodes is directly converted
into electricity without low-efficient combustion process.
As there is no heat/power conversion in these devices, their
energy efficiency is much higher than that of traditional power
units, and can reach 90%.

6. Benefits of fuel cells
Environmental Performance
Since hydrogen fuel cells don’t produce air pollutants or
greenhouse gasses, they can significantly improve our
environment.
Energy Efficiency
Fuel cells are 2 to 3 times more efficient than combustion
engines. For co-generation applications, where fuel cells generate
both heat and electricity, efficiencies can be close to 80%.
Versatile
Fuel cells are scalable, and provide everything from mill watts to
megawatts of power in a variety of uses - from cellphones, to
cars, to entire neighborhoods.
Health Benefits
Hydrogen fuel cells only produce heat and water – no toxins,
particles, or greenhouse gasses, which means cleaner air for us
to breathe.
Fuel Flexibility
There are many types of fuel cells, and each can operate in a
clean manner using different fuels including hydrogen, natural
gas, methanol, ethanol, and biogas.
Complementary
Fuel cells can readily be combined with other energy
technologies, such as batteries, wind turbines, solar panels, and
super-capacitors.

7. Some Limitations
 Hydrogen:
o Not readily available, must use other energy sources to
convert
o Infrastructure not in place
o Difficult to store/distribute
 High Capital Cost
 Non-technical barriers
o Could have dramatic impact

8. Future of Fuel Cells
2015 – 2025- Substantial markets for
Hydrogen-powered vehicles likely to
Start developing
2020: 5 to 10 million
Hydrogen-powered cars
2030: 50 million
Hydrogen powered cars
2040: 150 million
Hydrogen-powered cars

9. Types of Fuel Cells
 Polymer electrolyte membrane (PEM) fuel cells
 Direct methanol fuel cells
 Alkaline fuel cells
 Phosphoric acid fuel cells
 Molten carbonate fuel cells
 Solid oxide fuel cells
 Reversible fuel cells

10. POLYMER ELECTROLYTE MEMBRANE FUEL CELLS
Polymer electrolyte membrane (PEM) fuel cells—also called proton
exchange membrane fuel cells—deliver high power density and offer the
advantages of low weight and volume compared with other fuel cells. PEM
fuel cells use a solid polymer as an electrolyte and porous carbon
electrodes containing a platinum or platinum alloy catalyst. They need only
hydrogen, oxygen from the air, and water to operate. They are typically
fueled with pure hydrogen supplied from storage tanks or reformers.
PEM fuel cells operate at relatively low temperatures, around 80°C (176°F).
Low-temperature operation allows them to start quickly (less warm-up time)
and results in less wear on system components, resulting in better
durability. However, it requires that a noble-metal catalyst (typically
platinum) be used to separate the hydrogen's electrons and protons,
adding to system cost. The platinum catalyst is also extremely sensitive to
carbon monoxide poisoning, making it necessary to employ an additional
reactor to reduce carbon monoxide in the fuel gas if the hydrogen is
derived from a hydrocarbon fuel. This reactor also adds cost.
PEM fuel cells are used primarily for transportation applications and some
stationary applications. Due to their fast startup time and favorable power-
to-weight ratio, PEM fuel cells are particularly suitable for use in passenger
vehicles, such as cars and buses.

11. DIRECT METHANOL FUEL CELLS
Most fuel cells are powered by hydrogen, which can be fed to the fuel cell
system directly or can be generated within the fuel cell system by reforming
hydrogen-rich fuels such as methanol, ethanol, and hydrocarbon fuels.
Direct methanol fuel cells (DMFCs), however, are powered by pure
methanol, which is usually mixed with water and fed directly to the fuel cell
anode.
Direct methanol fuel cells do not have many of the fuel storage problems
typical of some fuel cell systems because methanol has a higher energy
density than hydrogen—though less than gasoline or diesel fuel. Methanol
is also easier to transport and supply to the public using our current
infrastructure because it is a liquid, like gasoline. DMFCs are often used to
provide power for portable fuel cell applications such as cell phones or
laptop computers.

12. ALKALINE FUEL CELLS
Alkaline fuel cells (AFCs) were one of the first fuel cell
technologies developed, and they were the first type widely used
in the U.S. space program to produce electrical energy and water
on-board spacecraft. These fuel cells use a solution of potassium
hydroxide in water as the electrolyte and can use a variety of non-
precious metals as a catalyst at the anode and cathode. High-
temperature AFCs operate at temperatures between 100°C and
250°C (212°F and 482°F). However, newer AFC designs operate
at lower temperatures of roughly 23°C to 70°C (74°F to 158°F). In
recent years, novel AFCs that use a polymer membrane as the
electrolyte have been developed. These fuel cells are closely
related to conventional PEM fuel cells, except that they use an
alkaline membrane instead of an acid membrane. The high
performance of AFCs is due to the rate at which electro-chemical
reactions take place in the cell. They have also demonstrated
efficiencies above 60% in space applications.

13. PHOSPHORIC ACID FUEL CELLS
Phosphoric acid fuel cells (PAFCs) use liquid phosphoric acid as
an electrolyte—the acid is contained in a Teflon-bonded silicon
carbide matrix—and porous carbon electrodes containing a
platinum catalyst. The electro-chemical reactions that take place
in the cell are shown in the diagram to the right.
The PAFC is considered the "first generation" of modern fuel
cells. It is one of the most mature cell types and the first to be
used commercially. This type of fuel cell is typically used for
stationary power generation, but some PAFCs have been used to
power large vehicles such as city buses.

14. MOLTEN CARBONATE FUEL CELLS
Molten carbonate fuel cells (MCFCs) are currently being
developed for natural gas and coal-based power plants for
electrical utility, industrial, and military applications. MCFCs are
high-temperature fuel cells that use an electrolyte composed of a
molten carbonate salt mixture suspended in a porous, chemically
inert ceramic lithium aluminum oxide matrix. Because they
operate at high temperatures of 650°C (roughly 1,200°F), non-
precious metals can be used as catalysts at the anode and
cathode, reducing costs.
Improved efficiency is another reason MCFCs offer significant
cost reductions over phosphoric acid fuel cells. Molten carbonate
fuel cells, when coupled with a turbine, can reach efficiencies
approaching 65%, considerably higher than the 37%–42%
efficiencies of a phosphoric acid fuel cell plant. When the waste
heat is captured and used, overall fuel efficiencies can be over
85%.

15. SOLID OXIDE FUEL CELLS
Solid oxide fuel cells (SOFCs) use a hard, non-porous ceramic
compound as the electrolyte. SOFCs are around 60% efficient at
converting fuel to electricity. In applications designed to capture
and utilize the system's waste heat (co-generation), overall fuel
use efficiencies could top 85%.
SOFCs operate at very high temperatures—as high as 1,000°C
(1,830°F). High-temperature operation removes the need for
precious-metal catalyst, thereby reducing cost. It also allows
SOFCs to reform fuels internally, which enables the use of a
variety of fuels and reduces the cost associated with adding a
reformer to the system. SOFCs are also the most sulfur-resistant
fuel cell type; they can tolerate several orders of magnitude more
sulfur than other cell types can. In addition, they are not poisoned
by carbon monoxide, which can even be used as fuel. This
property allows SOFCs to use natural gas, biogas, and gases
made from coal. High-temperature operation has disadvantages.
It results in a slow startup and requires significant thermal
shielding to retain heat and protect personnel, which may be
acceptable for utility applications but not for transportation. The
high operating temperatures also place stringent durability
requirements on materials.

16. Fuel Cells vs. Batteries
 Designed to be continuously powered
 Fuel source can be re-supplied without interrupting power
 Unlike batteries, the fuel source is not contained inside the
fuel cell - increases shelf life and decreases time before
replacement is necessary
 Produces water waste only
 Environmentally friendly - companies such as Dell must
currently offer recycling programs for batteries in order to
comply with government environmental regulations
 More efficient than batteries

17. Automotive Industry &
Hydrogen
 GM and others are looking to capitalize on the next
generation of cars
 After enormous success of rivals like Honda and
Toyota with hybrid vehicles
 GM, along with other domestic automotive makers
 Face serious threats of bankruptcy, making a large
R&D push difficult.
 Rivals such as Toyota and Honda are already ahead of GM
and Ford
Thank You

18. Submitted by
Vinit
Shahdeo

19. MY PROFILE
Thank You
NAME- VINIT SHAHDEO
REG. NO.-15BIT0335
B.TECH-IT
VIT UNIVERSITY
VELLORE