Environmental Engineering Reference
In-Depth Information
any zero-emissions classification. Reformers also create trace emissions
from burning some of the liquid fuel in order to create the heat necessary
to initiate the chemical reaction. Even direct methanol fuel cells (DMF-
Cs) which require no reformer or stored hydrogen do not have zero emis-
Energy Conversion Devices (ECD) of Troy, Michigan has announced
a potential breakthrough in solid hydrogen storage. ECD is one of the par-
ent companies of GM Ovonics, patent holder for the nickel metal hydride
battery. A hydride, by definition, is a solid material that stores hydrogen.
ECD uses a modified hydride powder to store the hydrogen elec-
tron. Typically you can only store 1-2% by weight of the hydrogen in a
hydride material. This is 1-2 grams of hydrogen for every 100 grams of hy-
dride. ECD is storing 7% by weight, which is more efficient than liquid or
compressed hydrogen. This is done by adding a high percentage of mag-
nesium. Typically it takes hours to get the hydrogen back out but ECD has
solved that.
Hydrogen fueling might also take place at a gas station that has an
underground reformer being fed by natural gas. The hydrogen could be
pumped into the car much the same as gasoline, filling the storage mate-
rial in less than three minutes. A tank for a high efficiency vehicle like the
PNGV cars would be about the size of a gas tank on today's mid-size car
and only slightly heavier than a current tank when filled with gasoline.
GM has a fuel cell-powered version of its Precept PNGV vehicle with a
500-mile range using solid hydrogen storage. Shell Oil formed a joint ven-
ture with ECD to further develop the storage method and supporting in-
A hydrogen infrastructure for fueling could cost hundreds of bil-
lions, since there is such a limited hydrogen-generating and distribution
system now. Decentralizing production, by having reformers in commer-
cial buildings and even in home garages in combination with local power
generation would reduce some of the cost. Larger reformers in neighbor-
hood facilities could be the service stations of tomorrow.
One factor in the shift to fuel cells is concern over climate changes.
Global warming is a factor of concern with the world population continu-
ing to grow rapidly and developing economies starting to demand private
cars. This creates more fuel demands and more urgency on environmental
fronts and alternative fuels.
The DOE provides support to American companies, but the level of
support has been less than the federal support in Germany and Japan. In
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