20-06-2012, 02:25 PM
hydrogen fuel cells
hydrogen fuel cells .pdf (Size: 1.53 MB / Downloads: 62)
Abstract
A fuel cell is a device that converts the chemical energy from a fuel into electricity
through a chemical reaction with oxygen or another oxidizing agent.[1] Hydrogen is the most
common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes
used. Fuel cells are different from batteries in that they require a constant source of fuel and
oxygen to run, but they can produce electricity continually for as long as these inputs are
supplied.
Hydrogen is the most common fuel, but hydrocarbons such as natural gas and
alcohols like methanol are sometimes used. Fuel cells are different from batteries in that they
require a constant source of fuel and oxygen to run, but they can produce electricity
continually for as long as these inputs are supplied.
Introduction
You've probably
heard about fuel cells. In
2003, President Bush
announced a program called
the Hydrogen Fuel
Initiative (HFI) during his
State of the Union Address.
This initiative, supported by
legislation in the Energy
Policy Act of 2005 (EPACT
2005) and the Advanced
Energy Initiative of 2006,
aims to develop hydrogen,
fuel cell and infrastructure technologies to make fuel-cell vehicles practical and cost-effective
by 2020. The United States has dedicated more than one billion dollars to fuel cell research
and development so far.
So what exactly is a fuel cell, anyway? Why are governments, private businesses and
academic institutions collaborating to develop and produce them? Fuel cells generate
electrical power quietly and efficiently, without pollution. Unlike power sources that use
fossil fuels, the by-products from an operating fuel cell are heat and water. But how does it
do this?
History of Fuel cell
In 1889, the term “fuel cell” was first coined by
Ludwig Mond and Charles Langer, who attempted to build a
working fuel cell using air and industrial coal gas. Another
source states that it was William White Jaques who first
coined the term "fuel cell." Jaques was also the first
researcher to use phosphoric acid in the electrolyte bath.
In the 1920s, fuel cell research in Germany paved
the way to the development of the carbonate cycle and
solid oxide fuel cells of today.
In 1932, engineer Francis T Bacon began his vital
research into fuels cells. Early cell designers used porous
platinum electrodes and sulfuric acid as the electrolyte
bath. Using platinum was expansive and using sulfuric acid
was corrosive. Bacon improved on the expensive platinum
catalysts with a hydrogen and oxygen cell using a less corrosive alkaline electrolyte and
inexpensive nickel electrodes.
It took Bacon until 1959 to perfect his design, when he demonstrated a five-kilowatt fuel
cell that could power a welding machine. Francis T. Bacon, a direct descendent of the other well
known Francis Bacon, named his famous fuel cell design the "Bacon Cell."
Types of fuel cell
The fuel cell will compete with many other energy conversion devices, including the
gas turbine in your city's power plant, the gasoline engine in your car and the battery in
your laptop. Combustion engines like the turbine and the gasoline engine burn fuels and use
the pressure created by the expansion of the gases to do mechanical work. Batteries convert
chemical energy back into electrical energy when needed. Fuel cells should do both tasks
more efficiently.
A fuel cell provides a DC (direct current) voltage that can be used to power motors,
lights or any number of electrical appliances.
There are several different types of fuel cells, each using a different chemistry. Fuel
cells are usually classified by their operating temperature and the type of electrolyte they use.
Some types of fuel cells work well for use in stationary power generation plants. Others may
be useful for small portable applications or for powering cars. The main types of fuel cells
include:
Solid oxide fuel cell (SOFC)
These fuel cells are best suited for large-scale stationary power generators that could
provide electricity for factories or towns. This type of fuel cell operates at very high
temperatures (between 700 and 1,000 degrees Celsius). This high temperature makes
reliability a problem, because parts of the fuel cell can break down after cycling on and off
repeatedly. However, solid oxide fuel cells are very stable when in continuous use. In fact,
the SOFC has demonstrated the longest operating life of any fuel cell under certain operating
conditions. The high temperature also has an advantage: the steam produced by the fuel cell
can be channeled into turbines to generate more electricity. This process is called cogeneration
of heat and power (CHP) and it improves the overall efficiency of the system.
Alkaline fuel cell (AFC)
This is one of the oldest designs for fuel cells; the United States space program has
used them since the 1960s. The AFC is very susceptible to contamination, so it requires pure
hydrogen and oxygen. It is also very expensive, so this type of fuel cell is unlikely to be
commercialized.
Molten-carbonate fuel cell (MCFC)
Like the SOFC, these fuel cells are also best suited for large stationary power
generators. They operate at 600 degrees Celsius, so they can generate steam that can be used
to generate more power. They have a lower operating temperature than solid oxide fuel cells,
which means they don't need such exotic materials. This makes the design a little less
expensive.
Phosphoric-acid fuel cell (PAFC)
The phosphoric-acid fuel cell has potential for use in small stationary powergeneration
systems. It operates at a higher temperature than polymer exchange membrane
fuel cells, so it has a longer warm-up time. This makes it unsuitable for use in cars.
Direct-methanol fuel cell (DMFC)
Methanol fuel cells are comparable to a PEMFC in regards to operating temperature,
but are not as efficient. Also, the DMFC requires a relatively large amount of platinum to act
as a catalyst, which makes these fuel cells expensive.
hydrogen fuel cells .pdf (Size: 1.53 MB / Downloads: 62)
Abstract
A fuel cell is a device that converts the chemical energy from a fuel into electricity
through a chemical reaction with oxygen or another oxidizing agent.[1] Hydrogen is the most
common fuel, but hydrocarbons such as natural gas and alcohols like methanol are sometimes
used. Fuel cells are different from batteries in that they require a constant source of fuel and
oxygen to run, but they can produce electricity continually for as long as these inputs are
supplied.
Hydrogen is the most common fuel, but hydrocarbons such as natural gas and
alcohols like methanol are sometimes used. Fuel cells are different from batteries in that they
require a constant source of fuel and oxygen to run, but they can produce electricity
continually for as long as these inputs are supplied.
Introduction
You've probably
heard about fuel cells. In
2003, President Bush
announced a program called
the Hydrogen Fuel
Initiative (HFI) during his
State of the Union Address.
This initiative, supported by
legislation in the Energy
Policy Act of 2005 (EPACT
2005) and the Advanced
Energy Initiative of 2006,
aims to develop hydrogen,
fuel cell and infrastructure technologies to make fuel-cell vehicles practical and cost-effective
by 2020. The United States has dedicated more than one billion dollars to fuel cell research
and development so far.
So what exactly is a fuel cell, anyway? Why are governments, private businesses and
academic institutions collaborating to develop and produce them? Fuel cells generate
electrical power quietly and efficiently, without pollution. Unlike power sources that use
fossil fuels, the by-products from an operating fuel cell are heat and water. But how does it
do this?
History of Fuel cell
In 1889, the term “fuel cell” was first coined by
Ludwig Mond and Charles Langer, who attempted to build a
working fuel cell using air and industrial coal gas. Another
source states that it was William White Jaques who first
coined the term "fuel cell." Jaques was also the first
researcher to use phosphoric acid in the electrolyte bath.
In the 1920s, fuel cell research in Germany paved
the way to the development of the carbonate cycle and
solid oxide fuel cells of today.
In 1932, engineer Francis T Bacon began his vital
research into fuels cells. Early cell designers used porous
platinum electrodes and sulfuric acid as the electrolyte
bath. Using platinum was expansive and using sulfuric acid
was corrosive. Bacon improved on the expensive platinum
catalysts with a hydrogen and oxygen cell using a less corrosive alkaline electrolyte and
inexpensive nickel electrodes.
It took Bacon until 1959 to perfect his design, when he demonstrated a five-kilowatt fuel
cell that could power a welding machine. Francis T. Bacon, a direct descendent of the other well
known Francis Bacon, named his famous fuel cell design the "Bacon Cell."
Types of fuel cell
The fuel cell will compete with many other energy conversion devices, including the
gas turbine in your city's power plant, the gasoline engine in your car and the battery in
your laptop. Combustion engines like the turbine and the gasoline engine burn fuels and use
the pressure created by the expansion of the gases to do mechanical work. Batteries convert
chemical energy back into electrical energy when needed. Fuel cells should do both tasks
more efficiently.
A fuel cell provides a DC (direct current) voltage that can be used to power motors,
lights or any number of electrical appliances.
There are several different types of fuel cells, each using a different chemistry. Fuel
cells are usually classified by their operating temperature and the type of electrolyte they use.
Some types of fuel cells work well for use in stationary power generation plants. Others may
be useful for small portable applications or for powering cars. The main types of fuel cells
include:
Solid oxide fuel cell (SOFC)
These fuel cells are best suited for large-scale stationary power generators that could
provide electricity for factories or towns. This type of fuel cell operates at very high
temperatures (between 700 and 1,000 degrees Celsius). This high temperature makes
reliability a problem, because parts of the fuel cell can break down after cycling on and off
repeatedly. However, solid oxide fuel cells are very stable when in continuous use. In fact,
the SOFC has demonstrated the longest operating life of any fuel cell under certain operating
conditions. The high temperature also has an advantage: the steam produced by the fuel cell
can be channeled into turbines to generate more electricity. This process is called cogeneration
of heat and power (CHP) and it improves the overall efficiency of the system.
Alkaline fuel cell (AFC)
This is one of the oldest designs for fuel cells; the United States space program has
used them since the 1960s. The AFC is very susceptible to contamination, so it requires pure
hydrogen and oxygen. It is also very expensive, so this type of fuel cell is unlikely to be
commercialized.
Molten-carbonate fuel cell (MCFC)
Like the SOFC, these fuel cells are also best suited for large stationary power
generators. They operate at 600 degrees Celsius, so they can generate steam that can be used
to generate more power. They have a lower operating temperature than solid oxide fuel cells,
which means they don't need such exotic materials. This makes the design a little less
expensive.
Phosphoric-acid fuel cell (PAFC)
The phosphoric-acid fuel cell has potential for use in small stationary powergeneration
systems. It operates at a higher temperature than polymer exchange membrane
fuel cells, so it has a longer warm-up time. This makes it unsuitable for use in cars.
Direct-methanol fuel cell (DMFC)
Methanol fuel cells are comparable to a PEMFC in regards to operating temperature,
but are not as efficient. Also, the DMFC requires a relatively large amount of platinum to act
as a catalyst, which makes these fuel cells expensive.