Re: Can you get plant cells to produce hydrogen rather than carbohydrates?

Your idea is great, but there are some problems:
Although one could probably insert into the plant the necessary bacterial 
gene(s) that will enable the plant to produce H2, the plant would probably 
use an intermediate of carbohydrate metabolism (pyruvate most likely) as a 
precursor for H2. That intermediate would then not be available to be 
completely oxidized in the tricarboxylic acid cycle. As a consequence, not 
enough ATP would be synthesized, and the so-modified plant cell would not 
be able to replicate. If one were to re-direct photosynthetic electron 
flow, probably not enough protons would be pumped to build up the 
necessary pH gradient (= proton motive force) across the thylakoid 
membranes that could drive ATP production. Furthermore, no NADP could be 
reduced to NADPH. Both NADPH and ATP are essential for the CO2 fixing 
reactions.