The document summarizes the workings and performance of molten carbonate fuel cells. It discusses that molten carbonate fuel cells operate at around 650°C, allowing the use of non-noble metal catalysts. The key reactions and components of the fuel cell are described, including the hydrogen oxidation reaction at the anode and oxygen reduction reaction at the cathode. Performance is affected by various factors like pressure, temperature, reactant gas composition and utilization, and impurities. Advantages include high efficiency and tolerance for internal reforming, while disadvantages include intolerance to sulfur and liquid electrolyte handling challenges.

1. Molten Carbonate
Fuel Cell
Prepared By:-
Nainesh M Patel
(13MCHN01)

2. Contents
• Introduction
• Working MCFC.
• Performance of Cell
• Effect of Pressure
• Effect of Temperature
• Effect of Reactant Gas Composition and Utilization
• Effect of impurities
• Advantages & Disadvantages
• Reference

3. INTRODUCTION
• The molten carbonate fuel cell operates at
approximately 650 C (1200 F).low-cost metal
cell components.
• A benefit associated with this high temperature is
that noble metal catalysts are not required for the
cell electrochemical oxidation and reduction
processes.
• Molten carbonate fuel cells are being developed
for natural gas and coal-based power plants for
industrial, electrical utility, and military
applications.

4. CELL REACTIONS

5. WORKING
• A molten carbonate (MC)fuel
cell consists of two flow field
plates an anode a molten
carbonate electrolyte and a
cathode hydrogen is directly
through channels in the flow
field plate and feeds into the
“anode” or negatively charged
electrode
• Oxygen and carbondioxide
feed into the “cathode” or
positively charged electrode.

6. WORKING MODEL
Anode :Ni-Cr/Ni-Al/Ni-Al-Cr
Cathode : lithiated NiO-MgO
Electrolyte : molten carbonate
carbonate ion (Co3--)

7. • When the hydrogen reaches the anode, the
catalyst encourage it to split into positively
charged protons and negatively charged electrons.
• The negatively charged electrons are not allowed
through the membrane.
• They are diverted so must go through an external
circuit generating electricity.
• When the electrons enter the cathode they are
combined with oxygen from the air and carbon
dioxide recycled from the used fuel.
• These molecules from a carbonate ion (Co3--).

8. • The negatively charged carbonate ions then move
through the electrolyte to the anode where they
combined with the protons to maintain the charge
balance.
• This is only possible if the electrolyte is very hot,
above 600 degree Celsius.
• The byproducts at the anode are carbon dioxide
and water.
• The carbon dioxide is separated and recycled to
the cathode side.

9. • Some of the heat produced in the process is
exhausted with the water in the from of vapor. A
cooling system remove the rest of it.
• The obtain desired amount of electrical power
individual fuel cells are combined in to fuel cell
“stacks”.
• A typical stack may consist of hundreds of fuel
cells.
• Increasing the number of cells in a stack increases
the voltage.

13. Performance
Cell performance for any fuel cell is a function
of
• Pressure
• Temperature
• Reactant gas composition & Fuel utilization
• Impurities

14. Effect of Pressure
• Increasing the operating pressure of MCFCs results in
enhanced cell voltages because of the…
• Increase in the partial pressure of the reactants.
• Increase in gas solubility.
• Increase in mass transport rates.
• Opposing the benefits of increased pressure are the
effects of pressure on undesirable side reactions such as
carbon deposition
2CO → C + CO2
• And methane formation (methanation)
CO + 3H2→ CH4 + H2O

15. • The addition of H2O and CO2 to the fuel gas modifies the
equilibrium gas composition so that the formation of CH4 is
not favored.
• Increasing the partial pressure of H2O in the gas stream can
reduce
• The change in voltage as a function of pressure change was
expressed as
• was based on a load of 160 mA/cm2 at a temperature of 650
C.
• It was also found to be valid for a wide range of fuels and
for a pressure range of 1 atmosphere ≤ P ≤ 10 atmospheres.

16. Effect of Temperature
• Increases with temperature change in
equilibrium composition
a - P is the partial pressure computed from the water gas shift equilibrium of inlet gas with
composition 77.5 percent H2/19.4 percent CO2/3.1 percent H2O at 1 atmosphere.
b - Cell potential calculated using Nernst equation and cathode gas composition of 30 percent
O2/60 percent CO2/10 percent N2.
c - Equilibrium constant for water gas shift reaction

17. • Changes with temperature and utilization to affect
the cell voltage.
• Change in the equilibrium gas composition with
temperature.
• The partial pressures of CO and H2O increase at
higher T because of the dependence of K on T.
• Change in gas composition, and the decrease in
E with increasing T, is that E decreases with an
increase in T.(E =equilibrium electrode potential)
• Operating cell, the polarization is lower at higher
temperatures

18. Effect of Reactant Gas Composition
and Utilization
• The voltage of MCFCs varies with the
composition of the reactant gases.
• The effect of reactant gas partial pressure,
however, is somewhat difficult to analyze.
• As reactant gases are consumed in an operating
cell, the cell voltage decreases in response to the
polarization (i.e., activation, concentration) and to
the changing gas composition.
• These effects are related to the partial pressures of
the reactant gases.

19. Effect of Impurities
• Sulfur
• The tolerance of MCFCs to sulfur compounds is strongly
dependent on temperature, pressure, gas composition, cell
components, and system operation (i.e., recycle, venting, gas
cleanup).
• <10 ppm H2S in the fuel can be tolerated at the anode.
• The adverse effects of H2S occur because of:
• Chemisorption on Ni surfaces to block active electrochemical
sites,
• Poisoning of catalytic reaction sites for the water gas shift
reaction, and
• Oxidation to SO2 in a combustion reaction, and subsequent
reaction with carbonate ions in the electrolyte.

20. Nitrogen Compounds
• NH3 and HCN do not appear to harm MCFCs
in small amounts.
• NH3 tolerance of MCFCs was 0.1 ppm.

21. Effect

22. Advantages
• Support spontaneous internal reforming of
light hydro-carbon fuels
• Generate high-grade waste heat
• Have fast reaction kinetics (react quickly)
• Have high efficiency
• Do not need noble metal catalysts

23. Disadvantages
• Have a high intolerance to sulfur. The anode in
particular cannot tolerate more than 1-5 ppm
of sulfur compounds (primarily H2S and COS)
in the fuel gas without suffering a significant
performance loss.
• Have a liquid electrolyte, which introduces
liquid handling problems.
• Require a considerable warm up period

24. Reference
• http://www.fuelcellenergy.com/why-fuelcell-energy/types-of-fuel-cells/
• http://www.ceret.us/HydrogenFuelcells/MC_FC.html (Animation)
• http://en.wikipedia.org/wiki/Molten_carbonate_fuel_cell
• Fuel Cell Handbook (Seventh Edition) By EG&G Technical Services, Inc.
• Module 4 fuel cell technology :collage of the desert.