ABSTRACT:
Technology is like a double edged weapon…..
which can turn either to a boon or bane..
depends only how you pursue it
and how you use it….
Energy is today’s basic necessity; we don’t produce energy but transfer it to different
forms and use it. We have selected this presentation “NON-CONVENTIONAL ENERGY”
because it suggests logical solutions to how we have produced energy and power for such a
long time till humans existed on earth. In this presentation we have described the general idea
of fuel cell energy with chemical reactions and processes involved in them. We have covered
the history of fuel cell, principle and its working, types of fuel cells, construction of low
temperature PEM fuel cell and benefits of fuel cells. There after we concluded up with the
applications of these fuels cells.
Non-Conventional Energy
INTRODUCTION:-
Energy is the primary and most universal measure of all kinds of work by human
beings and nature. Every thing that is happening in the world is the expression of flow of
energy in one of its forms. Most people use the word energy for input to their body and thus
think about crude fuels and electric power.
All of us know that neither energy can be created nor destroyed it can be just
transformed from one form to another. Now-a-days we are using mostly non-conventional
sources to generate electricity like solar energy, wind energy, chemical energy, co-generation,
geothermal, biomass energy, hydro energy, fuel cell energy. These energy converters were
developed mostly in 18th Century but the revolutionary changes occurred only in 20th and 21st
centuries.
HISTORY OF FUEL CELL:-
The principle of the fuel cell was discovered by German scientist Christian Friedrich
Schonbein in 1838 and published in the January 1839 edition of the “Philosophical magazine”.
Based on this work, the first fuel cell was developed by Welsh scientist Sir William Robert
Grove in 1843. The fuel cell he made used similar materials to today’s phosphoric-acid fuel
cell. It wasn’t until 1959 that British engineer Francis Thomas Bacon successfully developed a
5 k W stationary fuel cell. In 1959 a team led by Harry Ihrig built a 15 KW fuel cell tractor for
Allis-Chalmers which was demonstrated across the US at state fairs. This system used
potassium hydroxide as the electrolyte and compressed hydrogen and oxygen as the reactants.
UTC’s Power subsidy was the first company to manufacture and commercialize a large,
stationery fuel cell system for use as a co-generation power plant in hospitals, universities and
large office buildings. UTC power continues to market this fuel cell as the Pure Cell 200 KW
system.
In 2006 Staxon introduced an inexpensive OEM fuel cell module for system
integration. In 2006 Angstrom power, a British Columbia based company, began commercial
sales of portable devices using proprietary hydrogen fuel cell technology, trademarked as
“micro hydrogen”.
WHAT IS A FUEL CELL?
Fuel cell is a device that electrochemically converts the chemical energy of a fuel
and an oxidant to electrical energy. The fuel and oxidant are typically stored outside of
the fuel cell and transferred into the fuel cell as the reactants are consumed.
In principle a fuel cell operates like a battery. Unlike a battery, a fuel cell does not run
down are require recharging. It will produce energy in the form of electricity and heat as long
as fuel is supplied.
A fuel cell consists of two electrodes sandwiched around an electrolyte. Oxygen passes
over one electrode and hydrogen over the other, generating electricity, water and heat.
HOW DO FUEL CELLSWORK?
Anode: 2H2 4H+ + 4e-
Cathode: O2 + 4H+ + 4e- 2H2O
Overall: 2H2 + O2 2H2O + energy
A fuel cell generates electrical power by continuously converting the chemical
energy of a fuel into electrical energy by way of an electrochemical reaction. The fuel
cell itself has no moving parts, making it a quiet and reliable source of power. Fuel cells
typically utilize hydrogen as the fuel, and oxygen (usually from air) as the oxidant in the
electrochemical reaction. The reaction results in electricity, by-product water, and byproduct
heat.
Because the fuel is converted directly to electricity, a fuel cell can operate at
much higher efficiencies than internal combustion engines, extracting more electricity
from the same amount of fuel.
When hydrogen gas is introduced into the system, the catalyst surface of the
membrane splits hydrogen gas molecules into protons and electrons. The protons pass
through the membrane to react with oxygen in the air (forming water). The electrons,
which cannot pass through the membrane, must travel around it, thus creating the source
of DC electricity.
Individual fuel cells can be then combined into a fuel cell "stack". The number of fuel
cells in the stack determines the total voltage, and the surface area of each cell determines
the total current. Multiplying the voltage by the current yields the total electrical power
generated.
TYPES OF FUEL CELLS:
Fuel cells are generally categorized by their electrolyte—the material sandwiched
between the two electrodes. This material's characteristics determine the optimal
operating temperature and the fuel used to generate electricity. Each comes with its
particular set of benefits and short comings
Among all this fuel cells PEMFC has proved more efficient than Phosphoric acid.
Even though its temperature withstand is less than that of phosphoric acid, unlike
phosphoric acid PEMFCs don’t required much temperature for start conducting.
CONSTRUCTION OF LOW TEMPERATURE PEM FUEL CELLS:
The construction of the Low temperature fuel cell PEMFC Bipolar plate as electrode
with in-milled gas channel structure, fabricated from conductive plastics (enhanced with
carbon nanotubes for more conductivity); Porous carbon papers; Reactive layer, usually
on the polymer membrane applied; polymer membrane.
The materials used in fuel cells differ by type. The electrode/bipolar plates are usually
made of metal, nickel or carbon nanotubes, and are coated with a catalyst (like platinum,
nano iron powders or palladium) for higher efficiency. Carbon paper separates them from
the electrolyte. The electrolyte could be ceramic or a membrane.
A typical fuel cell produces about 0.86 volt. To create enough voltage, the cells are
layered and combined in series and parallel circuits to form a fuel cell stack. The number
of cells used is usually greater than 45 but varies with design.
H2 and Anode:
Hydrogen fuel (H2) is channeled to the anode, where the catalyst separates the
hydrogen's negatively charged electrons from the positively charged protons.
The membrane allows the positively charged protons to pass through to the cathode,
but not the negatively charged electrons.
The negatively charged electrons must flow around the membrane through an
external circuit. This flow of electrons forms an electrical current.
At the cathode, the negatively charged electrons and positively charged hydrogen
ions (protons) combine with oxygen to form water (H20) and heat.
require expensive containment structures. Constant improvements in the engineering and
materials used in these cells have increased the power density to a level where a device about
the size of a small piece of luggage can power a car.
BENEFITS OF FUEL CELL:
No other energy generating technology holds the combination of benefits that fuel
cells offer.
Energy Security. U.S. energy dependence is higher today than it was during the
"oil shock" of the 1970s, and oil imports are projected to increase. Passenger
vehicles alone consume 6 million barrels of oil every single day, equivalent to 85
percent of oil imports. If just 20 percent of cars used fuel cells, we could cut oil
imports by 1.5 million barrels every day.
Physical Security. Because of their distributed nature, fuel cells allow the country
to move away from reliance on central station power generation, and long-distance,
high voltage power grids, which are the most likely terrorist targets in any attempt to
cripple our energy infrastructure.
High Reliability/ High Quality Power. The National Power Laboratory estimates
that the typical computer location experiences 289 power disturbances a year that are
outside the voltage limits of the computer equipment. U.S. businesses lose $29
billion annually from computer failures due to power outages and are quickly
realizing that fuel cells may help prevent not only loss of power, but also loss of
dollars. Fuel cells offer clean, high quality power, crucial to an economy that
depends on increasingly sensitive computers, medical equipment and machines.
Fuel cells can be configured to provide backup power to a grid-connected customer,
should the grid fail. They can be configured to provide completely grid-independent
power or can use the grid as the backup system. Modular installation (the installation
of several identical units to provide a desired quantity of electricity) provides
extremely high reliability in specialized applications. Properly configured fuel cells
can achieve up to 99.9999% reliability, less than one minute of down time in a six
year period.
Fuel flexibility: The Primary fuel source for the fuel cell is hydrogen, which can be
obtained from natural gas, coal-gas, methanol, landfill Gas, and other fuels
containing hydrocarbons. This fuel flexibility means that power generation can be
assured even when a primary fuel source is unavailable.
Cogeneration Capability:- High quality heat is available for cogeneration, heating,
and cooling. Fuel cell exhaust heat is suitable for use in residential, commercial and
industrial cogeneration applications.
Efficiency: Because they make energy electrochemically, and do not burn fuel, fuel
cells are fundamentally more efficient than combustion systems. When the fuel cell
is sited near the point of use, its waste heat can be captured for beneficial purposes
(cogeneration). In large-scale building systems, these fuel cell cogeneration systems
can reduce facility energy service costs by 20% to 40% compared to conventional
energy service.
Fuel cell power generation systems in operation today achieve 40% to 50%fuelto-
electricity efficiency utilizing hydrocarbon fuels. Systems fueled by hydrogen can
consistently provide more than 50 percent efficiency. Even more efficient systems are
under development. In combination with a turbine, electrical efficiencies can exceed 60
percent. When waste heat is put to use for heating and cooling, fuel utilization can
exceed 85 percent. Fuel cell passenger vehicles are expected to be up to three times
more efficient than internal combustion engines, which now operate at 10 to 16 percent
efficiency.
Environmental Benefits: Air pollution continues to be a primary health concern
in America. Exposure to ozone, particulate, or airborne toxic chemicals has substantial
health consequences. Scientists are now directly linking air pollution to heart disease,
asthma and cancer. Recent health studies suggest polluted urban air is a comparable
health threat to passive smoking. Fuel cells can reduce pollution today and offer the
promise of eliminating pollution tomorrow.
APPLICATIONS:
FUEL CELL DRIVEN ELECTRIC CAR:-
If the fuel cell is provided with pure hydrogen, it has the potential to be up to
80% efficient. That is, convert 80% of the energy content of the hydrogen into
electrical energy. But, as we had learnt hydrogen is difficult to store in a car. When
we add a reformer to convert methanol to hydrogen, overall efficiency drops to about
30-40%.
accomplished by the electric motor and inverter. A reasonable number of the
efficiency of the motor/inverter is about 80%. So we have 30-40% efficiency at
converting methanol to electricity, and 80% efficiency converting electricity to
mechanical power. That gives an overall efficiency of about 24-32%.
TRANSPORTATION:- Fuel cells can be used to provide propulsion or auxiliary power
for transportation applications including cars, trucks, buses, trains, ships and submarines.
They have been used to provide auxiliary power on spacecraft for decades.
Stationary Power: Stationary fuel cell units can be used for back up power, power for
remote locations, stand-alone power plants for towns, cities, distributed generation for
buildings, and co-generation (in which excess thermal energy from electricity generation
is used for heat).
PORTABLE POWER:- Fuel cells can be used to power a variety of portable devices,
from handheld electronics like cell phones and radios, to large equipment such as
portable generators. They can be used for almost any application typically powered by
batteries but can last up to three longer before refueling.
MOBILE CHARGER:-The charger, based on a polymer electrolyte fuel cell (PEFC), IS
THE product of recent the collaboration between the mobile phone company and
Japanese firm Aquafiry, in which NTT Do Como recently bought a 36.5 per cent stake.
Although small, measuring only 24mm by 70mm, the companies claim that the device
can recharge a typical mobile phone three times before requiring a hydrogen fuel refill.
MILITARY APPLICATIONS:-
Miniature fuel cells for portable applications since soldiers are stating to carry a
range of enabling electronic technologies, computers, personal radios, displays and
thermal imaging, all intended to increase his effectiveness, lethality and survivability,
Right now, these devices are limited by their power source. Miniature fuel cells can
operate 10 times longer than conventional batteries used to power hand-held battlefield
computers, and are much more cost effective.
Stationary fuel cells for military applications can provide back up or standby
power for special operations and activities and provide power in remote areas.
CONCLUSION:
As the demand for energy continues to expand, the challenge to meet it grows. As our
demand for electrical power grows, it becomes increasingly urgent to find new ways of
meeting it both responsibly and safely. Hydrogen age is definitely on the fast track. Once
fuel cells find well – established applications other than automobiles, their impact could
snow ball. In the past, the limited factors of renewable energy have been the storage and
transport of that energy. With the use of fuel cells and hydrogen technology, electrical
power from renewable energy sources can be delivered where and when required cleanly,
efficiently and sustainable.
