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Lagniappe
Future in a Fuel Cell
By
Robert Campbell's Fuel Ghoul
In
the age of climate change, everyone is keen to help promote
an alternative future for automotive transportation. The
Oil Age may soon be over, and the time of cheap oil has definitely
come to a close. Innovation demands a new source of power
for humanity’s cars and trucks. Biodiesel, ethanol,
solar electric, compressed air and even steam powered systems
are being rushed into development as the world consumes 85
million barrels of crude oil everyday.
Fuel
Ghoul believes that mankind’s next energy source will
be wonderfully simple and infinitely practical, totally green
and one hundred percent renewable.
Hydrogen fuel cells might form half of the solution – extracting the
hydrogen (to power the fuel cells) is the other half of the equation.
When
Fuel Ghoul asks scientists 'What is the perfect automotive
energy source?’ they inevitably answer, ‘hydrogen’.
And when Fuel Ghoul asks them how they would turn that element
into energy they simply reply ‘fuel cells’, even
though the science isn’t one hundred percent obvious
yet, and the process of securing the hydrogen has yet to
become cost effective.
Today,
fuel cells are often mentioned in the news. Some say hydrogen
fuel cells will be the most widely used. Others say methanol
or ethanol would be more
appropriate for the transportation sector. And there are even some visionaries
who believe mankind will be refining gasoline for a long time yet, and that
fossil fuels will only be eclipsed by the dawn of fusion power.
With
an eye on the future, Fuel Ghoul took the time to read up
on fuel cells. These handy devices are designed similar
to batteries except they don’t store energy – they
convert the chemical energy of the input material directly
into electricity. The principle of the fuel cell was developed
by William Grove in 1839.
What is a hydrogen fuel cell?
A
fuel cell is an electrochemical device that combines hydrogen
and oxygen to produce electricity, with water and heat as
its by-product. As long as fuel is supplied, the fuel cell
will continue to generate power. Various types of fuel cells
exist, but the one automakers are primarily focusing on for
fuel cell cars is one that relies on a proton-exchange membrane,
or PEM.
A
simple hydrogen fuel cell consists of two conductors (an
anode and a cathode) separated by an ionic conductor – an
electrolyte (eg, a salt solution). Hydrogen is pumped to
the anode, and oxygen to the cathode. Hydrogen reacts with
charged particles (ions) in the electrolyte, producing water
and electrons. The electrons leave the fuel cell along wires;
this is the DC electricity generated by the cell.
The
electrons return to the fuel cell cathode where they combine
with oxygen and water to form ions which replace those consumed
at the anode. And so the cycle continues, with hydrogen and
oxygen being turned into water while generating electricity.
Fuel
cells in space
One
hydrogen fuel cell can generate up to 1.2 volts of DC electricity.
Individual cells can be wired together to produce greater
voltages or higher current. The space shuttle has 96 individual
cells arranged in three stacks. When hydrogen and oxygen
are pumped into the shuttle's fuel cells, they generate 28
volts of direct current as well as heat and water. The heat
is put to good use, vaporizing the liquid fuels before they
reach the fuel cells. Water flows into storage containers
for drinking and other uses.
Fuel Cells: Chapter Two
Today,
hydrogen and oxygen are commonly used as the fuel and oxidant.
The electrodes are made of porous carbon plates which are
laced with a catalyst (a substance
that accelerates chemical reactions). The electrolyte is usually potassium
hydroxide. At the anode, the hydrogen gas combines with hydroxide ions to
produce water vapor. This reaction results in some left over electrons. These
excess electrons are forced out of the anode and produce DC electric current.
At the cathode, oxygen and water plus returning electrons from the circuit
form hydroxide ions which are again recycled back to the anode. The basic
core of the fuel cell consisting of the manifolds, anode, cathode and electrolyte
is generally called the stack.
There
are three types of fuel cells that appear to be the most
promising. The Solid Oxide Fuel Cell or SOFC is the most
likely contender for both large and small electric power
plants. The Direct Alcohol Fuel Cell or DAFC appears to
be the most promising as a battery replacement for portable
applications such as cellular phones and laptop computers.
The Alkaline Fuel Cell AFC has been used in space applications
where hydrogen and oxygen are available.
Its
easy to see why scientists love fuel cells – they
have a lot of obvious advantages. Firstly, fuel cells produce
almost no emissions at the tailpipe (securing the hydrogen
could be messy though) and secondly the technology is safe
and reliable, modular, lightweight and quiet. Fuel Cells really
are tomorrow’s perfect power plants.
Fresh
ideas about alternative fuel, climate change and planet Earth's
new energy diet.
Robert
Campbell, lives
and works in Toronto Ontario as a television writer
/ producer. His
blog Fuel
Ghould is
on fresh ideas about alternative fuel, climate
change and
planet Earth's new energy diet.
Petroleumworld not necessarily share these views.
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