"Until now, to create large quantities of hydrogen, the most widespread method consisted in using hydrocarbons by dissociating the hydrogen atoms from the carbon atoms"
Oxygen point in a molecule of CH4 … Now, the reaction described in this sentence has nothing to do with hydrocarbons like … GAS, but everything to do with the electrolysis of water. You are therefore mistaken about the chemical reaction between the electrolysis of water and the CRACKING of natural gas (see links below). And it is with GAS that hydrogen is currently mass produced, thus rejecting large CO2 quantities
"The other method is to break up the water molecules to separate the components, but the latter requires a lot of energy."
More precisely, it requires electricity (electrolysis) OR high heat (pyrolysis), such as that which occurred inside the Fukushima reactors and which caused the explosion of concrete containments. several meters thick. Yes, that's what blew up the nuclear reactors, not the nuclear reaction directly. The cold source no longer existed and the residual heat began to increase until it was sufficient to separate the oxygen and hydrogen atoms from the water of the boiling water reactor (our reactors are different because under PRESSURE WATER). The zirconium tubes (aluminum and zircon alloy) which contain the MOX pellets (actually cylinders) have heated and a gas envelope (oxygen and hydrogen) has formed around them because they were immersed in water to boil. This is exactly what created the overpressure in the tanks and led to them exploding by OVERPRESSION. For information, our PWRs are fitted with hydrogen fuel cells to compensate for this possibility of the loss of the cold source. Remember that the same can happen with any pressure vessel, including including coal plants! With this ready that with coal, the fuel is outside and it is therefore simpler and easier to cut the supply of fuel which provides heat.
"Solar energy can be used in this method, but it is particularly long and tedious."
Again, and in the same paragraph, you confuse energy and electricity. Which is not quite the same thing. Hydrogen and electricity are ENERGY VECTORS, not primary energies. These are final energies obtained by machines which had to be manufactured and which use primary energy, more often than not, heat, therefore Saadi Carnot machines which are therefore subject to the laws of thermodynamics. Laws that tell us that the maximum efficiency cannot exceed 50% for the thermal machine to operate (TC / TF = 0.5 max).
For the rest, it would have been good to give the source of the information. I?ve already read it on other scientific and technical news sites, but the returns are not huge. And then, the bp is always the same: as long as the gas is so inexpensive and that cracking is much more profitable than this kind of techniques, they can only exist economically with subsidies. And who pays the subsidies? The state through our taxes and / or our direct consumption (CSPE and TICPE with us). That is to say, TAXES in addition.
Another way to mass produce hydrogen: http: //www.rtflash.fr/reacteurs-4eme-generation-produire-l-hydrogene-avec-nucleaire/article
Some explanations on the essentials of hydrogen: http: //www.cea.fr/jeunes/themes/les-energies-renouvelables/l-essentiel-sur-l-hydrogene
Production from carbon sources: http: //www.promes.cnrs.fr/index.php? Page = production-of-hydrogen-from-hydrocarbon-based resources
Conclusion, the author (Mathieu.M) posts an article without giving the source and in addition does not know and does not understand well the energy, chemical and economic chains for the current production of hydrogen. This will only make readers think that a miracle solution has been found, but by reading the source, they will realize that we are far from it.