By Robert Spénard
Hydrogen is known as the simplest and most abundant element on Earth. There are twelve recognized processes to produce hydrogen. Six using fossil fuels and six using renewable resources. Each process has great benefits and disadvantages. The twelve processes are:
From fossil fuels
- Steam Reformation
- Partial oxidization
- Auto thermal Reformation
- Water-Gas Shift, Preferential Oxidation, and Methanation
- Desulfurization
- Plasma reforming
From renewable resources
- Biomass gasification
- Pyrolysis and copyrolysis
- Aqueous phase reforming
- Electrolysis
- Photo electrolysis
- Thermochemical water splitting
Currently 95% of the world’s hydrogen is produced using steam Reformation.
Wikipedia describes steam Reformation as:
[1]Steam reforming or steam methane reforming (SMR) is a method for producing syngas (hydrogen and carbon monoxide) by reactions of hydrocarbons with water. Commonly natural gas is the feedstock. The main purpose of this technology is hydrogen production.
{\displaystyle CH_{4}+H_{2}O\rightleftharpoons CO+3H_{2}}The reaction is strongly endothermic (ΔHSR = 206 kJ/mol).
Hydrogen produced by steam reforming is termed ‘grey hydrogen’ when the waste carbon dioxide is released to the atmosphere and ‘blue hydrogen’ when the carbon dioxide is (mostly) captured and stored geologically – see carbon capture and storage. Zero carbon ‘green’ hydrogen is produced by thermochemical water splitting, using solar thermal, low- or zero-carbon electricity or waste heat, or electrolysis using low- or zero-carbon electricity. Zero carbon emissions ‘turquoise’ hydrogen is produced by one-step methane pyrolysis of natural gas. Steam reforming of natural gas produces most of the world’s hydrogen. Hydrogen is used in the industrial synthesis of ammonia and other chemicals.
[2]Photoelectrochemical Water Splitting also known as Photoelectrolysis of water is considered to be the most environmentally friendly process for producing hydrogen at this time. Wikipedia defines this process as:
Photoelectrolysis of water, also known as photoelectrochemical water splitting, occurs in a photoelectrochemical cell when light is used as the energy source for the electrolys of water, producing dihydrogen which can be used as a fuel. This process is one route to a “hydrogen economy”, in which hydrogen fuel is produced efficiently and inexpensively from natural sources without using fossil fuels. In contrast, steam reforming usually or always uses a fossil fuel to obtain hydrogen. Photoelectrolysis is sometimes known colloquially as the hydrogen holy grail for its potential to yield a viable alternative to petroleum as a source of energy; such an energy source would supposedly come without the sociopolitical undesirable effects of extracting and using petroleum.
Some researchers have practiced photoelectrolysis by means of a nanoscale process. Nanoscale photoelectrolysis of water could someday reach greater efficiency than that of “traditional” photoelectrolysis. Semiconductors with bandgaps smaller than 1.7eV would ostensibly be required for efficient nanoscale photoelectrolysis using light from the Sun.
An article dated June 17, 2022 posted on Hydrogenworld.com titled “Large-scale offshore green hydrogen production a step closer to reality”[3] Which announced a memorandum of understanding between green hydrogen producer Lhyfe[4] and shipbuilder Chantiers de l’Atlantique[5] in the creation of an offshore/onshore hydrogen fuel chain. This is an indicator of the direction mass hydrogen fuel production is headed.
Hydrogen can be mass produced in many ways, from environmentally unfriendly to environmentally beneficial. Time, economic, political and end user demands will determine which process the world will use to mass produce hydrogen fuel.
[1] Source Steam reforming – Wikipedia
[2] Source Photoelectrolysis of water – Wikipedia
[3] Source Large-scale offshore green hydrogen production a step closer to reality (hydrogentechworld.com)
[5] Chantiers de l’Atlantique – Parce que la mer est notre avenir (chantiers-atlantique.com)
