No there are many other methods such as Photo-splitting, biomethane steam reforming, pyro-reforming of glycerine ... Electrolysis (electron splitting) of water using renewable electricity is not the only way to produce net-zero hydrogen. Few other approaches are there at the developing stages. For example, catalytic photo-splitting of water is such a concept with more tremendous potential. Steam reforming of biomethane and pyro-reforming glycerine of renewable origin are also potential ways of producing net-zero hydrogen. However, it is quite clear these concepts have not yet been adopted by investors for their investments. Most of these methods are in development at research laboratories. Neither has been included in standard definitions nor in the scopes of green hydrogen by major think tanks in the industry or academia. Anyway, we can not neglect the potentials of these alternatives, especially the Photosplitting method given it can perform without competing for electricity as in the case of electrolysers.
Steam Biomethane Reforming (SBR)
Biomethane steam reforming is a process that involves converting biogas, which is a mixture of methane and carbon dioxide, into hydrogen gas. This is typically done by passing the biogas over a catalyst, such as nickel, at high temperatures and pressures. The methane in the biogas reacts with water to produce hydrogen and carbon dioxide. Biomethane steam reforming can be considered a net-zero process because the carbon dioxide produced during the reaction is equal to the amount of carbon dioxide that was originally present in the biogas. This means that no additional carbon dioxide is released into the atmosphere. Biomethane steam reforming is considered a more sustainable option because it uses a renewable source of methane (biomass) instead of fossil fuels. However, the process of producing biomethane steam reforming may not be as energy-efficient as the process of producing blue hydrogen. Additionally, the availability of biomass for biomethane production may be limited in some areas.
Photo-splitting of water
The photo-splitting of water is a process that uses sunlight to split water molecules into hydrogen and oxygen. This process can be used to produce hydrogen gas, which can be used as a clean, renewable fuel. The concept of water photo splitting is technically feasible, and research is ongoing to develop efficient and cost-effective ways to implement it. The efficiency of the most promising set-ups is currently around 10-15%, but research is continuing to improve this. The process of water photo-splitting of water typically involves using a photoelectrochemical cell, which consists of a semiconductor material (such as silicon) coated with a catalytic material (such as platinum or iridium oxide). When sunlight hits the cell, it excites the electrons in the semiconductor material, which causes them to migrate to the catalytic material. This creates a flow of electrons, which can be used to split water molecules into hydrogen and oxygen gas. There are several advantages to using water photo-splitting to produce hydrogen, including the fact that it uses a renewable source of energy (sunlight) and does not produce any greenhouse gases or other pollutants. However, one disadvantage is that the process is currently not very efficient, and it may be challenging to scale up to industrial levels. Additionally, the cost of the catalytic materials used in the process can be relatively high.
Pyro-reforming of glycerine
Pyro-reforming of glycerine is a process that involves using high temperatures and a catalyst to convert glycerine (a byproduct of biodiesel production) into hydrogen gas. This process can be used to produce hydrogen gas, which can be used as a clean, renewable fuel. The concept of pyro-reforming of glycerine is technically feasible, and research is ongoing to develop efficient and cost-effective ways to implement it. The efficiency of the most promising set-ups is currently around 70-80% at the bench top level (laboratory set-up), but research is continuing to improve the scaling up to the commercial level. The process of pyro-reforming typically involves passing glycerine vapour over a catalyst, such as nickel or copper, at high temperatures (around 600-900°C). The glycerine reacts with the catalyst to produce hydrogen gas, carbon monoxide, and carbon dioxide. The hydrogen gas can then be collected and used as fuel. One advantage of using pyro-reforming of glycerine to produce hydrogen is that it can make use of a waste product (glycerine) that would otherwise be discarded. Additionally, the process can be relatively efficient compared to other methods of hydrogen production. However, one disadvantage is that the high temperatures and pressures required for the reaction can be challenging to achieve and maintain, and the process may not be as sustainable as other methods of hydrogen production. Additionally, the cost of the catalysts used in the process can be relatively high.
Biohydrogen production from waste
Biohydrogen production is the process of using microorganisms, such as bacteria and algae, to produce hydrogen gas from organic waste material. This process is considered a sustainable and environmentally friendly alternative to traditional hydrogen production methods, which often rely on fossil fuels. The organic waste material is first broken down by the microorganisms into simpler organic compounds, such as sugars and fatty acids, through a process known as fermentation. These compounds are then converted into hydrogen gas through a process called hydrogenogenesis. Hydrogen gas can be collected and used as a clean and renewable energy source. This process typically occurs through the action of enzymes called hydrogenases, which catalyze the reduction of protons (H+) to hydrogen gas (H2). Hydrogenogenesis is a key step in the production of biohydrogen, which is hydrogen gas produced from organic waste material through the action of microorganisms. Biohydrogen has the potential as a clean and renewable energy source and is considered a sustainable alternative to traditional hydrogen production methods, which often rely on fossil fuels.