Make your own Hydrogen gas generator using a mason jar, steel wool pot scrubbers and a sock

[caraher]

10. And some people on the Internet can correctly sort through claims without building stuff

Consider your weed eater guy... Anyone using aluminum in a process of any kind and claims not to be using electricity has no idea where aluminum comes from! It's about as close to embodied pure electricity as any material I can think of! All he's doing is getting back some of the energy used in extracting aluminum metal from bauxite.

For an analysis of this "electricity-free" option there's a report from the Department of Energy's hydrogen program that lays out why this is pretty much a non-starter as a means to fuel vehicles:

The purpose of this White Paper is to describe and evaluate the potential of aluminum-water reactions for the production of hydrogen for on-board hydrogen-powered vehicle applications. Although the concept of reacting aluminum metal with water to produce hydrogen is not new, there have been a number of recent claims that such aluminum-water reactions might be employed to power fuel cell devices for portable applications such as emergency generators and laptop computers, and might even be considered for possible use as the hydrogen source for fuel cell-powered vehicles....

... the cost of producing hydrogen by this approach is dictated by the cost of aluminum metal. The November 2007 commodity price for aluminum is $2.36 per kg. At this price, hydrogen from an aluminum-water hydrogen generation approach would cost approximately $21 per kg H2. Even assuming high volume production, the DOE target range for hydrogen cost of $2-3 per kg H2 would not be met.

I thought this part toward the end was particularly interesting, as it is not merely about the terrible economics:

Another factor that should be considered is the amount of aluminum that would be required to produce hydrogen for large numbers of hydrogen-fueled vehicles. It is estimated that the fueling of 300 million vehicles would require 64 million metric tons of hydrogen per year. Since it requires 9 tons of aluminum to produce 1 ton of hydrogen through the aluminum-water reaction, this means that the fueling of 300 million vehicles would require 575 million metric tons of aluminum per year. To put this number in perspective, the world-wide production of aluminum in the year 2006 was 24 million metric tons (www.world-aluminium.org). Thus, the hydrogen fueling of very large numbers of vehicles via the aluminum-water reaction would require an expansion of world-wide aluminum production by approximately a factor of 25. In addition to the capital cost of new aluminum smelting facilities, the electricity consumption for aluminum production would have to increase by a similar factor.

This is a prodigious amount of electricity:

Aluminum refining from aluminum-bearing bauxite ore uses the Bayer process chemistry which forms a hydrate which is essentially the same as the reaction product in the proposed aluminum- water reactions described above. The hydrate is then calcined to remove the water to form alumina. The alumina is electrolytically reduced into metallic aluminum at about 900 C using the Hall-Heroult Process, producing a metal with 99.7% purity (see Figure 10). The smelting process requires continuous operation to be efficient. For 2005 (the latest figures reported by the Institute), the North American average energy used to reduce the oxide to the metal (smelting) is 15.552 kWh per kg of Al. This number does not include the energy used in mining and transporting the ore, the energy for processing the ore to the oxide, or the energy used in casting or carbon plants.

This means 875 million tonnes * 1000 kg/tonne * 15 kWh/kg = 8.6 trillion kWh of electricity annually devoted to aluminum production, in order to generate hydrogen to fuel 300 million cars. Maybe at this point electric cars start to look like a better option?

eppur_se_muova is no armchair/keyboard "expert" but someone who knows science, and clearly grasps the concepts in play here as well as anyone.