Saturday, 22 February, 2025
Green hydrogen is produced when we use renewable energy like wind and solar to separate water molecules into hydrogen and oxygen using an electrolyzer. The electrolyzer splits the hydrogen atoms from the oxygen atoms. Then the hydrogen can be stored and used when energy is needed.
Basically, instead of CO2, the only thing emitted by vehicles running on green hydrogen is water. These vehicles have a container where compressed hydrogen gas is stored. That hydrogen is then directed to the fuel cell, where a chemical reaction occurs that produces water vapour and the electricity that will move the vehicle.
Hydrogen can be produced by electrolysis where electricity is used to split water into hydrogen and oxygen. If renewable generation is the Reference of electricity, then renewable hydrogen is produced without greenhouse gas emissions. There are also other methods of producing renewable hydrogen including biogas, pyrolysis, solar thermal energy, and even microbes.
Green hydrogen is produced through the electrolysis of water. Electrolysis is a technique that uses direct electric current to drive an otherwise non-spontaneous chemical reaction. The Greek word "lysis" means to separate or break, so in terms, electrolysis would mean "breakdown via electricity".
Source: https://www.hydrogennewsletter.com/faq-general-green-hydrogen-knowledge/
Approximately 9 kg of pure water is needed. Oxygen is 16 times heavier than hydrogen which means 89 % of the mass of water has been taken up by Oxygen. Therefore, we can approximately take that 9 kg of water is needed to produce 1 kg of hydrogen. At standard temperature and pressure, 9 kg of water means 9 L. So practically we need to take 9 L of water.
Source: https://www.hydrogennewsletter.com/faq-general-green-hydrogen-knowledge/
When producing green hydrogen through water electrolysis, it is CO2 emission-free and the by-products are only pure oxygen and heat.
Source: https://www.norwegianhydrogen.com/green-hydrogen/faq
Hydrogen gas can be produced using many different pathways. Commercial pathways today utilize different feedstocks such as methane (currently the most
common), water, coal, and other chemical carriers (e.g., biomass). These hydrogen production pathways and other promising pathways are described in more detail below:
Some of the advanced pathways are not yet at the commercial scale but have the potential for highly efficient clean hydrogen generation. Advanced pathways currently being pursued include photoelectrochemical water-splitting, thermochemical water-splitting, biological fermentation, and photobiological hydrogen production.
Hydrogen and carbon dioxide form the building blocks for some of the most important chemicals that we need such as methanol, methane, diesel, gasoline, etc. These materials are crucial as they are used in industrial processes, used to produce other useful chemicals and in transport applications as fuels. Currently these chemicals are produced from fossil fuels.
Producing these chemicals artificially through renewable processes is a prerequisite to decarbonize this sector. This can be achieved by sourcing green hydrogen from renewable electricity/ water electrolyzer plants and capturing and utilizing the by-product carbon dioxide from industrial processes and biogas production plants.
Source: https://www.norwegianhydrogen.com/green-hydrogen/faq
By electrolysis, yes, Sea Water can be used and produced Hydrogen and Oxygen. It is environmentally friendly if we can use Sea Water for this purpose. However, chloride corrosion and precipitate formation on the electrodes is a critical problem. Many attempts have been taken in seawater electrolysis; however, long-term stability has not been demonstrated by such efforts.
Source: https://www.hydrogennewsletter.com/faq-general-green-hydrogen-knowledge/
'Clean' generally means there are very low to zero carbon emissions in the production of hydrogen. This term covers hydrogen both with and without carbon capture and storage. The colour terms denote the relative cleanness of hydrogen.
ACP’s compromise framework positions “first-mover” green hydrogen to be cost-effective in the early years of deployment. At today’s capital cost for a new electrolyzer, industry participants are confident that an initial annual time matching structure will allow them to achieve green hydrogen production at costs competitive with today’s gray hydrogen market. As the industry matures, achieving economies of scale and a robust supply chain, capital costs are expected to fall. This will enable a transition to a stricter clean energy accounting structure—i.e., hourly matching.
Source: https://cleanpower.org/wp-content/uploads/2023/06/ACP_GreenHydrogenFramework_FAQ.pdf
There are shortcomings to green hydrogen that prevent it from fully contributing to energy transformation. Obstacles include the lack of infrastructure (e.g., transport and storage) as well as the cost of production. As the International Renewable Energy Agency (IRENA) points out, green hydrogen was still up to three times more expensive in 2019 than grey hydrogen. Another difficulty is that up to 30-35 % of energy is lost in the electrolysis process. In addition, it needs to be ensured that it is sustainable and produced from fully renewable sources.
Around 300 megawatts (MW) of electrolyzer capacity was installed worldwide by mid-2021, with 18.5 MW installed and 602.6 MW firm planned capacity in the United States as on May 2022 (Arjona 2022, IEA 2021). Alkaline electrolyzer (61% of total installed capacity) is a mature technology, while solid oxide electrolysis cell electrolyzer is a relatively new but promising technology that has the potential to operate in reverse mode as a fuel cell as well, although this capability is yet to be demonstrated in a commercial application. PEM technology (31% of total installed capacity) is being used extensively in recent electrolyzer installations and has the potential to be operated more flexibly than alkaline electrolyzers.
Over the past decade, deployments of PEM electrolyzers have increased from the kilowatt to megawatt scale, with higher capacity deployments (>10 MW) under development (IEA 2021).