All Gallium Is Not Divided Into Three Parts
Schemes for conquering climate change by substituting hydrogen for carbon stand or fall on where the hydrogen is to come from ? Everything from solar cell photolysis to hydroelectricity and geothermal power figures in future tense hydrogen evangelism, but in the real world it comes cheaply only from natural gas or coal -- which utterly obviates the point of using hydrogen to reduce CO2 emissions.
This is old hat- so to revive interest , a Perdue professor is publicizing a seemingly cheap and easy way to generate hydrogen. Based on aluminum, It looks carbon free on first glance. Many reactive metals liberate hydrogen from water, but those reactions can be spectacularly energetic. Tossing one pound ingots of sodium into Essex Bay was my own preferred ( and widely applauded ) 4th of July fireworks finale until liability lawyers, the EPA , and the post-9/11 aversion to things that go bang banished such instant pyrotechnics from the marketplace.
Aluminum is potentially just as reactive- mixed with granulated rust and ignited , it yields white hot molten iron. Yet aluminum foil is non-flammable, because a tenacious oxide layer coats the metal, preventing runaway reaction with air or water. If disrupted, say by amalgamating an aluminum bar's surface with mercury, the light metal reacts on contact with water , releasing a hissing froth of hydrogen bubbles.
But mercury too has succumbed to a sort of paranoia--it has vanished from medicine ,and a whole cottage industry seeks to ban it from light bulbs and switches as well. So what other low melting metal can turn normally passive aluminum into a well behaved hydrogen source ?
Chemically speaking , non-toxic gallium is to aluminum as silicon is to carbon- lower melting and heavier. But while silicon is common as sand and dirt cheap, gallium is as rare and expensive byproduct of processing aluminum ore. Useful in semiconductors, its high price reflects the huge energy cost of concentrating it - bauxite contains roughly only 1 atom of gallium per million of aluminum.Yet Galliu is thre for the taking,, as common as copper in the rocks of the Eart'scrust, and enough to enable a hydrogen car would coust little more than the platinum melts in the catalytic converter of a truck engine Because though melts in the palm of your hand , just a small percentage added to aluminum yields a crystalline alloy , GaAl28 suitable for hydrogen generation.
GaAl28 is being hyped along the lines of :
Instant Hydrogen -- Just Add Water .
But first you need some aluminum- and aluminum takes a lot of electricity to make . Since 51% of America's electricity comes from coal , that half of the energy economy is off limits from a Green Hydrogen perspective. Note that LA is especially dependent- a coal-fired Prius is not what California Greens have in mind. But much imported aluminum embodies hydro-electricity from Norway or Canada , so can't we celebrate this new found route to clean green internal combustion? Surely the white soup of gallium spiked Milk of Alumina that would remain in the former gasoline tanks of our hydrogen cars could be endlessly recycled back to the dams and nuclear electric plants whence the fuel-metal came ?
Not so fast. Gallium does more to aluminum than facilitate hydrolyzing it into hydrogen. Since gallium melts in the palm of your hand, the silvery stuff can be slapped on to anything made of aluminum- an airplane say, or an engine block . It wicks into the grain boundaries of structural aluminum alloys like hot water being sucked into a sugar cube. And behold, the stuff just falls apart. Give an aluminum baseball bat a dab of gallium , and a girl scout can break it with a karate chop.
Long before The Transportation Safety Authority arose , the FAA enacted a ferocious ban on air transport of gallium , and as energy conservation leads to ever greater use of light aluminum alloys in vehicles for land sea and air , the gallium solution to the hydrogen conundrum must overcome more than its already parlous enegy economics