Abstract
Portable fuel cells are poised to achieve significant growth as units become
smaller and fuels less expensive. According to Susan Eustis, lead author of
the study, gEconomies of scale do not entirely solve the inherent high costs
of high grade metallic catalysts used in micro fuel cells. Nanotechnology is
poised to provide new ways to create advanced materials that can be used to
implement portable fuel cells. More catalyst price reductions are needed to
make portable fuel cells competitive with thin film batteries. Portable fuel
cells are useful in cities to power bicycles and for advanced multimedia
electronics that draws a lot of power.h
Most of the developing world, where energy and environmental problems abound,
still gets around on 2 wheels. 2% of the 1.5 billion population in China owns
a car. Cities have started banning the use of 2 - stroke engine motorcycles in
favor of LPG scooters and electric bicycles.
19 million electric bicycles were purchased in 2008. The trend is expected to
continue. As more people need to travel further each year, fuel cells take on
a role in short distance travel. As economies evolve, fuel cells provide a
role for green energy. Purchasing power constraints and air pollution issues
stimulate the need for low cost, zero carbon transportation solutions.
Portable fuel cell vendors are strategically positioned to develop and
implement solutions. Technology costs continue to decrease. Practical fuel
solutions continue to develop. Experiments with portable fuel cell products
are starting to take place in various parts of the world.
Nanotechnology is being used to implement a variety of portable fuel cell
solutions. Many different nanotechnology techniques are being explored. One is
of a silicon structure, approximately 400 microns deep, much thicker than the
10 - micron depth of a membrane in a traditional PEM - based cell. This design
is expected to enable a much larger reaction surface area, enabling high power
in a small form - factor. To compress more power into smaller volumes,
researchers have begun to build fuel cells on the fuzzy frontier of
nanotechnology. Silicon etching, evaporation, and other processes borrowed
from chip manufacturers have been used to create tightly packed channel arrays
to guide the flow of fuel through the cell.
jThe point is to pack a large catalytic surface area into a wafer - thin
volume. This approach is evolving, going beyond two - dimensional aspects to
gain more surface area. Methods improve the performance of nano - scale fuel
cells.
Three - dimensional structures improve current electrocatalysts that have
traditionally been expressed on a flat surface. Two dimensional catalysts give
hundreds of microamps per square centimeter, while three dimensional catalysts
increase the surface area by orders of magnitude.
Fuel channels are evolving in ready - made in a commonly available, porous
alumina filters costing only about $1. The filter is riddled with neat,
cylindrical holes only 200 nanometers in diameter, and was initially used in
labs as a template for the growth of nanowires.
Nanowires can be grown in a platinum - copper alloy, then dissolving the
copper by soaking the filter in nitric acid creates electrodes. In place of a
solid nanowire, each hole is left with a porous platinum electrode. The
partially dissolved wires are structurally complex, as befits their random
nature, and have an enormous surface area for their size.
The market size for portable fuel cell power at $80.1 million in 2008 is
estimated to reach $4.4 billion dollars by 2015. Existing markets are from
mobile homes and PCs used remotely. Strong growth comes as hybrid fuel cell
systems evolve to support thin film batteries. The fuel will come from
renewable energy sources.
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