Reducing greenhouse gas emissions and addressing the gradual disappearance of fossil fuels figure among the challenges the planet must face in the years to come. Hydrogen can and indeed must play an important role in the energy transition.
When an electric current is passed through water using two electrodes, the water molecules are decomposed into oxygen and hydrogen gas, in a process known as “electrolysis”.
Water electrolysis of is a non-spontaneous chemical reaction that consumes electricity to produce hydrogen and oxygen.
The electric current decomposes the water molecule into ions of hydroxide (OH)- at the cathode and into H+ protons at the anode. The protons accept electrons in an oxidation reaction thus forming hydrogen gas.
In and of itself, water electrolysis does not release any CO2. But in the overall calculation, the production of electricity must be taken into account. In the case where the electricity used is produced from sources that do not emit CO2 (renewables, etc.), hydrogen will be produced without releasing any greenhouse gas.
High-temperature steam electrolysis uses less energy because, since the reaction takes place between 700°C and 1,000°C, cell performance (kinetics) is vastly improved. This technology could, for example, be coupled with a set of solar mirrors that concentrate the Sun’s rays to reach these very high temperatures, which would enable to produce hydrogen cleanly (i.e., releasing virtually no greenhouse gas).
Did you know? ? Water electrolysis is an experiment that is often performed by high school students. An electric current passed through water produces 1 volume of O2 and 2 volumes of H2.
Through the process of photosynthesis, living organisms manage to produce hydrogen by using sunlight only.
Producing hydrogen using only sunlight and water may sound like the stuff of science fiction. But in fact, many microorganisms naturally produce hydrogen using light, in a process known as photosynthesis.
This is true of various single-celled green algae and some cyanobacteria, which have the advantage of producing hydrogen from solar energy using only water.
Thismethod for producing hydrogen does not result in any direct greenhouse gas emissions. Today, it is in the stage of laboratory experimentation. Researchers are trying to understand, copy and optimize this natural process in the hope of possibly industrializing it.
Elaboration selon les principes de ACV des bilans énergétiques, des émissions de gaz à effet de serre et des autres impacts environnementaux induits par l'ensemble des filières de véhicules électriques et de véhicules thermiques, VP de sement B (citadine polyvalente) et vul à l'horizon 2012 et 2020. Source : ADEME
Type : Documents and reports Theme : Politics, economy / sciences Release : 29-10-2015 Summary: Reducing greenhouse gas emissions and addressing the gradual disappearance of fossil fuels figure among the challenges the planet must face in the years to come. Hydrogen can and indeed must play an important role in the energy transition. Since the technologies that allow for the safe production and use of hydrogen are now mature, this carbon-free molecule can enable the shift to a "clean" world. Hydrogen has the capacity to store primary energy, particularly renewable energies. Combined with a fuel cell battery, it can also make this energy available in the form of electricity in a large number of applications, starting with those that pertain to mobility. But while the technical difficulties are in the process of being resolved today, responses to the economic and financial challenges have yet to be found: going forward, it will be necessary to structure large-scale industrial and commercial deployments. And doing so will require new forms of global cooperation between the private sector and public policymakers at the international level. In a word, launching the energy transition requires a paradigm shift.