> jim wrote:
> >
>
> > There are already known green methods of producing hydrogen in a
> > beneficial way. One method is for farmers to process field stover. The
> > carbon can be separated from the hydrogen in farm plant residue. That
> > has 2 positive impacts. The hydrogen is an excellent fuel and the carbon
> > in the form of bio-char is an excellent soil amendment. The effect would
> > be to reverse several millenia of damage caused by farming and other
> > human land use practices that have removed more carbon from the soil
> > than all the carbon that has been added to the environment from fossil > > fuels.
> > The effect of depleted soil carbon may in the long term be worse for
> > man's future than loading the atmosphere with excess carbon. The main
> > difference between arable soil and desert soil is the amount of carbon
> > it contains. Soil depletion of carbon reduces the capability of plant
> > growth. Plants remove carbon from the atmosphere. In other words
> > hydrogen as a fuel could be a part of a process of reversing what has
> > really has been a trend over the last 3000-5000 years of turning the
> > entire land mass of the globe slowly into a desert by removing carbon
> > from the soil.
> >
> > -jim
>
> What is the reaction that seperates the hydrogen from the carbon and
> other materials, and in what form (graphite?) is the released carbon?
formatting link
The reaction is called pyrolysis. The carbon produced from plant residue is a spongy charcoal that is nowadays given the name "biochar". But there is nothing new about the process. Basically you just heat the plant residue to 550F and you get C + CO + H2. There are simple processes for separating those components. I know of at least one commercially available system that uses CO output as the energy source for the heating and the H2 and carbon are the products.
The charcoal can be used as an energy source also. But as a soil amendment it may be far more valuable. When added to soil it has been shown to significantly increase yields and reduce need for fertilizer, water and energy inputs. Plus it also has the effect of reducing CO2, NO2 and CH4 emissions from farmed soils. Agriculture (tilling the soil in particular) is a leading sources of the release of those gasses into the atmosphere.
-jim