Fuel cells and their micro applications

FUEL CELL AND IT’S MICRO- APPLICATIONS

A Presentation By:-

Mihir Kulkarni

10CH027

Manas Orpe

10CH030

Guided By:-

Prof. P.N. DangeSchematics of reactant flow in a MCFC

WHAT IS A FUEL CELL?

It is a galvanic cell or electrochemical power source 

it generates electrical energy with water and heat as its by-product

both the reactants and the products are liquids or gases

CONSTRUCTION & WORKING OF A FUEL CELL

Has two electrodes, anode and cathode

An electrolyte, which carries electrically charged particles from one electrode to the other

A catalyst, which speeds the reactions at the electrodes.

Overall reaction is split into two partial reactions : oxidation and reduction

Process begins when Hydrogen molecules enter anode Catalyst coating separates hydrogen’s negatively charged

electrons from the positively charged protons Electrolyte allows protons to pass through to cathode, but not

electrons Instead electrons are directed through an external circuit which

creates electrical current Oxygen molecules pass through cathode Oxygen and protons combine with electrons after they have

passed through the external circuit Oxygen and protons combine with electrons to produce water and

heat

CONSTRUCTION & WORKING OF A FUEL CELL

TYPES OF FUEL CELL

1] Phosphoric acid fuel cell (PAFC)

Electrolyte is phosphoric acid Efficiency is 40 to 80 percent Operating temperature – 150 to 200oC (300 to 400o F) Output - up to 200 kW PAFCs tolerate a carbon monoxide concentration of about 1.5 percent

2] Alkaline fuel cell (AFC)

Operate on compressed hydrogen and oxygen. Generally use solution of potassium hydroxide (chemically KOH) in water as their electrolyte. Efficiency is about 70 percent Operating temperature is 150 to 200o C, (about 300 to 400o F) Cell output ranges from 300 W to 5 kW.

3] Proton-exchange-membrane fuel cell (PEMFC)

Work with a polymer electrolyte in the form of a thin, permeable sheet Efficiency is about 40 to 50 percent Operating temperature is about 80o C (about 175o F) Cell outputs generally range from 50 to 250 kW. Reactions : Anode (oxidation): H2 2H+ + 2e-

Cathode (reduction): ½ O2 2H+ +2e- H2O

Overall : H2 + ½ O2 H2O

4] Direct-methanol fuel cell (DMFC)

Specific content of chemical energy of about 6 kWh/kg Operating temperatures are in the range 50-120 °C, Power outputs between 25 watts and 5 kilowatts

Reactions :

Anode (oxidation) : CH3OH + 60H- 5H2O + 6e- + CO2

Cathode (reduction) : 3/2 O2 + 3H2O + 6e- 6OH- Overall : CH3OH + 3/2 O2 CO2 + 2H2O

5] Molten-carbonate fuel cell (MCFC)

Use high-temperaturecompounds of salt (like sodium or magnesium) carbonates (chemically CO3) as the electrolyte Efficiency ranges from 60 to 80 percent Operating temperature is about 650o C (1,200 o F) Output upto 2 megawatts (MW) Reactions :

Overall reaction : CO + ½O2 CO2

Oxidation reaction : CO + CO32- 2CO2 + 2e-

Reduction reaction : ½O2 + CO2 + 2e- CO32-

6] Solid-oxide fuel cell (SOFC)

Use a hard, ceramic compound of metal (like calcium or zirconium) oxides (chemically, O2) as electrolyte Efficiency is about 60 percent Operating temperatures are about 1,000o C (about 1,800 o F) Cells output is up to 100 kW

Reactions :Reduction reaction : ½O2 + 2H+ + 2e- H2OOxidation reaction : H2 2H+ + 2e- Overall reaction : H2 + ½O2 H2O

APPLICATIONS

Transportation

Stationary Power Stations

Telecommunications

Micro Power

Transportation : All major automakers are working to commercialize a fuel cell car.Automakers and experts speculate that a fuel cell vehicle will be commercialized by 2010.

Stationary Power Stations : Over 2,500 fuel cell systems have been installed all over the world in hospitals, nursing homes, hotels, office buildings, schools and utility power plants.

Telecommunications : Due to computers, the Internet and sophisticated communication networks there is a need for an incredibly reliable power source. Fuel Cells have been proven to be 99.999% reliable

APPLICATIONS

APPLICATIONS

Micro Power : • Consumer electronics could gain drastically longer

battery power with Fuel Cell technology.• Cell phones can be powered for 30 days without

recharging.• Laptops can be powered for 20 hours without

recharging.

ADVANTAGES

Physical Security

Reliability

Efficiency

Environmental Benefits

Battery Replacement/Alternative

Military Applications

ADVANTAGES

Physical Security : Both central station power generation and long distance, high voltage power grids can be terrorist targets in an attempt to cripple our energy infrastructure.

Reliability : Properly configured fuel cells would result in less than one minute of down time in a six year period. U.S. businesses lose $29 Billion a year from computer failures due to power outages.

Efficiency : Because no fuel is burned to make energy, fuel cells are fundamentally more efficient than combustion systems.

ADVANTAGES

Environmental Benefits : Fuels cells can reduce air pollution today and offer the possibility of eliminating pollution in the future.

Battery Replacement/Alternative : Fuel Cell replacements for batteries would offer much longer operating life in a packaged of lighter or equal weight.

Military Applications : Fuel Cell technology in the military can help save lives because it reduces telltale heat and noise in combat.

LIMITATIONS

Economic Problems :

Manufacturing cost of fuel-cell power plants is very high.

The most important components of all p.e.m.f.c. and d.m.f.c.’s is very expensive, about 700 $/m2.

Total cost of a 5-kW p.e.m.f.c power plant is be about 1200 $/kW.

In comparison cost of an analogous I.C. engine is 500-1500 $/kW.

LIMITATIONS

The Problem Of Lifetime : Satisfactory lifetime for smooth operation. 3 years lifetime for small plants in portable devices. 5 years for electric vehicles. 10 years for large stationary multi-megawatt power plants.

Samples of single p.e.m.f.c and stacks have been successfully operated for several thousands of hours.

But not enough data available for general use of these type of fuel cells.

RENEWABLE ENERGY ACT : FOR INDIA'S FUTURE NEEDS

Solar water heating to be made mandatory throughout the urban areas of the country by 2012, in a phased manner.

Widespread application of co-generation concepts (heat and power) for lighting, heating and cooling

REFERENCES

Fuel Cells: From Fundamentals to Applications, S. Srinivasan, Springer, New York, 2006

Fuel Cell History Part 1, G. Wand, “Fuel Cell Today” June 16, 2006

Handbook of Fuel Cells: Fundamentals, Technology, Applications (four volumes), W. Vielstich, A. Lamm, and H. Gasteiger (editors), Wiley, Chichester, UK, 2003

"Confusion and Controversy: Nineteenth-Century Theories of the Voltaic Pile," pp. 133-157 in F. Bevilacqua and L. Fregonese,

Nuova Voltiana: Studies on Volta and his Times, vol. 1 (2000)