Fuel cells - powering your home, your car tomorrow?
by P.J. Lakhapate
Fuel cell vehicles will probably overtake gasoline-powered cars in the next
20 to 30 years, meaning that fuel cell technology has the possibility of
becoming main street technology and not niche technology. If current predictions
hold true, fuel cells are likely to penetrate everywhere where energy is used
from laptops to vehicles, from home to business. But what exactly is a fuel
cell, how does it work and why are billions being poured into this research?
Why fuel cells?
Globally the demand for energy is ever increasing. In the USA, passenger
vehicles alone consume 6 million barrels of oil every single day equivalent to
85% of oil imports. The use of coal, oil or any hydrocarbon fuel leads to the
generation and release into the atmosphere of carbon, nitrogen and sulphur oxide
gases.
NASA has observed that the ozone in the earth's atmosphere has been depleted
by 0.12 % compared to that of the 1979 level. Depletion of the Ozone layer
allows the transmission of more harmful ultraviolet rays. CFCs and nitrogenous
oxides are responsible for the depletion of ozone.
On the other hand, emissions of CO2 gas into the atmosphere is a
cause of global warming. So, if we want to avoid generation of carbon monoxides
and carbon dioxide, we need to look at alternate sources of energy such as the
Hydrogen fuel cell, which cell generates only water after combustion.
How does it work?
In principle, a fuel cell operates like a battery. Unlike a battery, a fuel
cell does not run down or 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.
Hydrogen fuel is fed into the anode of the fuel cell. Oxygen (or air) enters
the fuel cell through the cathode. Facilitated by a catalyst, the 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 or diesel or biogas. Emissions from this type of system would still be
much lower than emissions from the cleanest fuel combustion processes.
So where does the hydrogen come from?
Hydrogen can be obtained naturally from by enzymes. The single celled
organism, cyanobacteria, produces hydrogen through its normal metabolic
functions. It can grow in air and water and contains enzymes that absorb
sunlight for energy. These split molecules of water thus producing hydrogen.
Also, in the partial oxidation reforming process CO2 without emission of
nitrogen and sulphur oxides. Finally, solar and wind energy can be used to
generate hydrogen and oxygen by electrolysis of water.
Uses of fuel cells
Sir William Grove built the first fuel cell in 1839. In 1960 fuel cells were
chosen for furnishing power to the Gemini and Apollo spacecraft and still
provide electricity and water for space shuttles.
Home and work
In commercial buildings, more than 200 Fuel Cell systems have been installed
all over the world, from hospitals, hotels, office buildings, schools to utility
power plants and airport terminals, providing primary power or backup. Fuel
cells can reduce facility energy service cost by 20% to 40% over conventional
energy service.
There are three main components in a residential fuel cell system: the
hydrogen fuel reformer, the fuel cell stack and power conditioner. The fuel
reformer extracts hydrogen from hydrocarbon fuel. The fuel cell stack converts
the hydrogen and oxygen from air into electricity, water vapour and heat. The
power conditioner then converts DC current to AC current which is required in
domestic applications.
Fuel cell vehicles
Some of the most exciting developments are to be seen in fuel cell vehicle
technology. Many vehicle manufacturers speculate that fuel cell vehicles can be commercialised
by 2004. Research by certain motor industries suggest that the fuel cell car
engine price would be equivalent to that of the internal combustion engine, in
years to come. According to the Environment Protection Agency in the USA, the
gasoline based fuel cell vehicle will give 1.34 times the present mileage and
methanol based fuel will give 2.31 times the present mileage for passenger cars
and light duty trucks.
Portable power
Miniature fuel cells will change the telecommunication world, powering
laptops and palm pilots hours longer than batteries. Other applications for
micro fuel cells include pagers, video recorders, portable power tools and low
power remote devices such as hearing aids, smoke detectors, burglar alarms,
hotel locks and meter readers.
Landfill and wastewater
Fuel cells currently operate at landfills and wastewater treatment plants in
the U.S.A. for reducing emissions and generating methane gas.
How safe would a hydrogen fuel cell vehicle be?
The hydrogen would be stored in one or more fibre wrapped composite tanks
that could survive 50 mph head on collisions, engulfment by a diesel fuel, fire
and pressures at 2.25 times design pressure. Furthermore fuel cell vehicles will
carry 60% less total energy than gasoline, making it less of a potential fire
hazard. In the event of a collision, a switch would shut off the flow of
hydrogen via a solenoid valve or valves and will cut off electric power from the
battery. Hydrogen has 52 times greater buoyancy and a 12.2 times greater
diffusion coefficient than gasoline. Thus hydrogen will disperse much more
quickly than gasoline or natural gas. Also, hydrogen's lower flammability limit
is four times greater than that of gasoline.
Advantages
Fuel cells would dramatically reduce air pollution, decrease oil consumption
and improve business opportunities. Fuel Cells are ideal for power generation,
either connected to electric grids to provide supplemental power and backup
assurance for critical areas, or installed as a grid independent generator for
onsite service in areas that are inaccessible by power lines. Since Fuel Cells
operate silently they reduce noise pollution, while the waste heat from a fuel
cell can be used to provide hot water or space heating.
There are several different designs and types of fuel cells from direct
methanol fuel cell (dmfc) for cellular phones and laptops, to alkaline fuel
cells used by NASA in the Apollo to the regenerative fuel cell currently being
researched. For more on specific designs, enter here.
Expected demands for fuel cell technology
Fuel cell technology is a multibillion-dollar industry. According to Allied
Business Intelligence Inc (ABII) the expected demand for fuel cells is as follow
in the USA will be US$ 0.218 billion in 2002, rocketing to US$ 10 billion in
2010. The expected break-up for the year 2004 is $US millions, is 850
million for electric power generation, 750 million for motor vehicles, 200
million for portable electrical equipment, 200 million for military/aerospace
technology and the rest 400 million.
As per ABII, the overall fuel cell energy generating capacity will increase
by a factor of 250. For example, the fuel cell electricity generating capacity
will jump to 15000 MW in 2011 from just 75 MW in the year 2001.
At present fuel cell power plants cost about $3000 per kilowatt. It is predicted
that the fuel cell will become popular if the cost drops below $1000 per
kilowatt.
In the nature there is nothing like punishment or reward. There are only
consequences. If we pollute the atmosphere, the entire planet is at stake.
To buy the time fuel cell technology can act as an intermediate technology
as it will reduce pollution levels considerably.
More Information:
P. J. Lakhapate is a chemical engineer from UDCT, Mumbai.
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