Salt Water System Could Generate (small amounts of) Hydrogen

[OKIsItJustMe]

http://www.physorg.com/news156596965.html

Salt Water System Could Generate Hydrogen

March 18th, 2009 by Lisa Zyga

(PhysOrg.com) -- The idea of generating hydrogen from salt water has often been claimed to work effectively. However, the systems proposed so far generally require a much greater energy input than the energy they produce, making them impractical for energy generation. Now, a recently revived system may be able to cheaply generate a small amount of power.

In the proposal, physicist Roberto De Luca from the University of Salerno in Italy has suggested that flowing salt water could generate an electromotive force, which in turn could generate an electric power output. In his theoretical analysis, he considers letting salt water (containing sodium and chlorine ions) run through a rectangular pipe that has two metal electrodes on the sides, under the influence of a perpendicular magnetic field. In this set-up, the Lorentz force acts on the sodium and chlorine ions in the salt water, creating a Faraday voltage across the two electrodes, and producing an electromotive force.

"I started considering the question Dr. Pasquale Desideri, a Roman chemist, asked," De Luca told PhysOrg.com. "If a transverse magnetic field is applied to salt water flowing in a thin rectangular pipe, would an electromotive force appear at the sides of the pipe itself? This question was interesting both from a didactical and a scientific point of view. Didactically, one could come up with an interdisciplinary lecture, making a comparison between the electrical transport properties of the 'Fermi sea' (the collection of free electrons in a metal) and the 'ordinary sea' (which a physicist could conceive as a collection of rather free Na+ and Cl- ionic charges diluted in water, besides a place to go in summertime)."

De Luca discovered that an experiment conducted in 1972 (by Wright and Van Der Beken) had demonstrated that Desideri's hypothesis was true: salt water flowing in a pipe under a transverse magnetic field does show an effect, similar to the Hall effect, in conducting metals. De Luca thought that this simple fact deserved more attention.

As he showed in his analysis, in order to produce a steady current in this device, the positive and negative electrodes experience different reactions. At one electrode, water is reduced to its components, resulting in oxygen and hydrogen gas. At the other electrode, chlorine ions are oxidized, producing chlorine gas.

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In this illustration of the system, salt water flows through a rectangular pipe under the influence of a perpendicular magnetic field, B0. The Lorentz force causes the charged sodium and chlorine ions to accumulate near the metal plates on the sides of the pipe, generating a constant electric field, E. Image credit: R. De Luca.

[Recursion]

1. It's one of those Maxwell tarpits

In principle it works, but there are significant realization problems. This is one of those proposals (and he's not the first to suggest it) that physicists love and engineers hate. I'm an engineer.

[HiFructosePronSyrup]

2. So the energy is really coming from the water being forced through the pipe.

i.e. he's reinvented the waterwell.