ALTERNATIVE FUEL CELLS
ABSTRACT
Research and development throughout the world for an effective alternate to the fossil
fuel energy has continuously persisted and fuel cell technology is here to stay. The fuel
cell is the newest source of energy that offers many benefits over conventional sources of
energy such as gasoline power IC engines or coal powered plants.
A fuel cell is a continuous feed primary cell. It uses hydrogen and oxygen to
produce electric current with the only by products being heat and pure water. Fuel cells
produce DC current and they can be used in the same manner as batteries. They do not
require any recharging.
The race between fuel cells and IC engines has reached its mid way and the former has
already competed the later due to its higher efficiency, zero emissions of obnoxious gases
and usage of renewable sources of energy as fuel. As a coin has two sides fuel cell also
has some disadvantages. Some of them at the current time in the nutshell are that they
are generally large, expensive and difficulty in the storage and transportation of pure
hydrogen. In spite of all these problems the development of fuel cells has geared up due
to the green house gases emitted by IC engines. These have created environmental
hazards like global warming and ozone layer depletion, which are to a stage of concern
now. So we can surely say fuel cells are the power of future. The origin, working and
application of fuel cells are reviewed in this paper.
INTRODUCTION
Energy conservation is a major problem in the present scenario. Man is looking
for cheaper, cleaner and efficient ways for his various necessities. IC engines have been
serving man since many years. This 115 years old dinosaur refuses to die as it gets
cleaner and more efficient each year. Though they have come a long way IC engines
have to go into the dark if the development of 160 years old. Technology of fuel cell
continuous at its current pace.
Why all the interest in Fuel Cell Vehicles
High potential for improved fuel and vehicle efficiency.
Double the fuel efficiency
Reduced CO2 emissions
Potential for a very low or zero criteria emissions vehicle.
Provide customer needs in an environmentally sound package
Potential for a new vehicle concept
WORKING OF FUEL CELL
A fuel cell consists of two electrodes sandwiched around an
electrolyte. Oxygen passes over one electrode and (or air) enters the fuel cell
through the cathode. Encouraged by a catalyst, the hydrogen over the other,
generating electricity,
water and heat. Hydrogen fuel is fed into the "anode" of the fuel cell. Oxygen hydrogen
atom splits into a proton and an electron, which take different paths to the cathode.
The proton passes through the electrolyte. The electrons create a separate current
that can be utilized before they return to the cathode, to be reunited with the
hydrogen and oxygen in a molecule of water.
A fuel cell system, which includes a "fuel reformer" can utilize the
hydrogen from any hydrocarbon fuel - from natural gas to methanol, and even gasoline.
Since the fuel cell relies on chemistry and not combustion, emissions from this type of a
system would still be much smaller than emissions from the cleanest fuel combustion
processes.
TYPES OF FUEL CELLS
Parameter
Alkaline
Fuel cell
Process
Requires
pure
hydrogen
and oxygen
Operating
temperature
152C
Application
suitability
Where used
Technology
Solid oxide
Fuel Cell
Proton
Exchange
Membrane
Fuel cell
Complex
system
design
Uses fuel
directly
without a
fuel
processor
Uses
relatively
impure fuel
Uses solid
polymer
membrane
as an
electrolyte
200C
6500C
400 to
10000C
1000C
Stationary
power
applications
with existing
installations
More
complex
than
phosphoric
acid fuel
cells due to
the use of
higher
temperature
and use of
molten
electrolytes
Molten
Phosphoric
Carbonate
acid Fuel cell
Fuel cell
JAPAN, USE US, JAPAN for
AND EUROPE constant
NASA
mid to large power in
large utility
Apollo
scale
applications
space
stationary
(1.8 mw
programs power and
general
prototype
applications
tested)
Suitable for
Ideally
large to very suited for
large
transport
stationary
and small
power
transport
applications applications
NASA
Gemini
space
program
Compact and
Demo stage.
produce
very early
electricity to
stages of
the size 1 to
development
250 kW
When
introduced
1960s
1970s
2002/03
Demo/evalu Commerciall
ation stage y available
NEW CONCEPT VEHICLES ARE
APPROACHING THE MARKET
FUEL FOR FUEL CELLS
Hydrogen
Hydro-carbon based fuels
Expected to be near time and long time
fuel of choice. Storage and transportation
requirements already in place
Fuel reformer is required to extract
hydrogen
Multiple feeds in the intermediate stage
Alternatives
hydrogen/methanol/clean petroleum
derivatives/natural gas
DIFFERENCE BETWEEN FUEL CELL AND BATTERY:
Both the fuel cell and a battery deliver power from a chemical
reaction .In a battery the chemical reactants stored within the battery are used up during
the reaction and the battery must be recharged are thrown away. But this is not the case in
a fuel cell. The reactants are stored externally. Therefore it produces electricity as long as
fuel is delivered. A fuel cell is refueled instead of recharging.
NOTE:
The voltage from a single cell is about
0.7 volts, just about enough for a light
bulb. When the cells are stacked in a
series, the operating voltage increases
to 0.7 volts multiplied by the number of
cells stacked.
The power requirement per vehicle is between 5 kW to 15 kW and fuel cells of 50 to
200 kW are already under commercial production. It is expected that small portable
with under 3 kW capacity could be in market by 2005 which could trigger a rise in
consumption in portable appliances.
Battery powered vehicles are 80% efficient. But taking into account recharging
efficiency is better than today's vehicles but not as efficient as fuel cell vehicles.
APPLICATIONS
Personal
Power backup, portable applications
Consumer electronics personnel computer
Utilities like lawn mowers etc.
No noise and air pollution
Waste heat produced can be utilized for other purposes.
Transport
Battery substitution applications.
Personnel vehicle engine substitution.
Fuel cells being incorporated into buses, locomotives, airplanes etc.,
Eliminates emission of green house gases.
Provides wide range of speeds as long as fuel is supplied.
Lubrication and maintenance problems are eliminated.
Public installations
Used in hospitals, hotels, offices, schools, utility power plants, air port terminal.
Public utilities like traffic signals.
Used in wastewater treatment plants and landfills.
Military applications
Saves money and reduces pollution at military installations.
Saves lives and material by reducing tell tale heat and noise.
PROS AND CONS
Pros
Cleaner technology due to zero emissions.
Uses renewable sources of energy as fuel.
Does not require recharging.
Quieter than IC engines due to the absence of moving parts.
No energy losses due to heat transfer, exhaust etc.
Reduction in efficiency is eliminated due to the absence of combustion.
Cons
Large size nearly 8 sq. ft.
Expensive i.e. almost 10 times to that of conventional automobile IC engines.
Difficulty in storage and transportation of pure hydrogen.
Reduction of efficiency due to the usage of hydrocarbon as a source of hydrogen.
Gasoline powered IC engines of today are capable of giving 40 to 50 MPG(miles
per gallon) but when used in fuel cell it is 80 MPG but gasoline is also one of the
fastest disappearing fossil fuel.
CHALLENGES TO BE FACED
EFFICIENCY GRAPH
THE ULTIMATE SCENARIO
CONCLUSION
The IC gasoline engine has been in development for decades. It has
made great advances in efficiency, power and cost. However it is nearing the end of line
in its equilibrium. The efficiency is leveling off and so is power output.
The FC on the other hand is just beginning on its road to perfection. The
fuel cell's efficiency is already beyond the efficiency of IC engine and is going to go well
beyond where it is today. The road to the perfect fuel cell is just beginning and we have
an excellent start.
REFERENCES:
Alternative fuelsand environment:Frances S Sterett
Alternative fuels:Robert Baer
Alternative fuel vehicles:Robin segal
