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Old 03-19-2008, 12:34 AM
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DaveInDenver DaveInDenver is offline
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Join Date: Jun 2006
Location: Larimer County
Posts: 8,475

Water cracking for fuel, eh? I can't quite put my finger on what's bugging me about this.

Hydrogen by aqueous electrolysis:
H2O + 447 kJ/mol → H2 + 0.5 O2
Breaking water into its elements takes about 120 watt-hours to split 1 mol of water. This reaction is quite endothermic. BTW, creating 1kg of H2 from water takes about 60,000 watt-hours by electrolysis and the general rule of thumb is 1kg of hydrogen is the same energy equivalent as 1 gallon of gas. If you assume it costs $0.25 per kw-hr from the power company, creating the energy equivalent of 1 gallon of gasoline by breaking water into hydrogen would cost about $15 for that 60 kw-hr.

Creating hydrogen by carbon monoxide and water through inorganic gas-water shift reaction:
CO + H2O → CO2 + H2 + 40.4 kJ/mol
Now this reaction is slightly exothermic, but has to be done at high temperatures, at least 130 degrees C. Something strikes me wrong about this, just not sure what. It's often considered non-economical because of the high heat required for the reaction, but I just dunno. Also this already happens in the catalytic converter, so you'd have to change that and the EPA and CARB isn't gonna like not having the nitrogen oxides converted into N2 and O2. Hmmm, what am I missing? Regretting that I slept through chem in summer session, too.
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