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The green hydrogen is a clean, renewable and eco-friendly way to produce hydrogen. Hydrogen is a key component of fuel cells and can be used to create electricity, heat or water. Hydrogen can be produced from water using electrolysis. This process uses electricity to split the hydrogen from oxygen. The green hydrogen production process utilises renewable energy sources, such as solar or wind power, to power the electrolysis process. This means that no fossil fuels are used to produce hydrogen and there are no emissions released into the atmosphere during production. In a commercial facility the green hydrogen production process can be more efficient and cost effective than traditional methods. Currently there are limited commercial facilities that produce hydrogen using this method.

Grey hydrogen

is a process where natural gas is converted to hydrogen using steam methane reforming. This is the traditional method used in the production of hydrogen. Natural gas is converted to hydrogen by adding steam to a mixture of natural gas and air at a high temperature. The hydrogen produced in this process contains high levels of contaminants, including carbon monoxide and carbon dioxide. These contaminants must be removed from the hydrogen before it is used in the hydrogen fuel cell or other hydrogen applications. Producing clean hydrogen using a grey hydrogen process requires additional steps, equipment and chemicals to remove these contaminants from the hydrogen. These steps add to the cost and energy required to produce hydrogen and can also lead to increased emissions. The Green Hydrogen Process produces clean hydrogen without the need for these additional steps and equipment.

Blue hydrogen

The concept of “blue hydrogen” was proposed as an alternative to green hydrogen. Blue hydrogen is produced through a conventional natural gas reforming process that uses coal rather than natural gas as the fuel source. The production of blue hydrogen results in higher levels of greenhouse gas emissions when compared to the production of green hydrogen. Green hydrogen is produced by steam reforming of natural gas. This generates fewer emissions than conventional natural gas reforming processes because it only releases the energy contained in the natural gas. In contrast, blue hydrogen requires the combustion of coal to generate the heat for the reaction, resulting in greater greenhouse gas emissions.

Green hydrogen is produced by electrolysis of water, which is 50% less carbon intensive than steam reforming. The primary cost of producing green hydrogen is the cost of electricity. Under certain conditions, such as excess wind power or off-peak periods of high electricity prices, the break-even point for green hydrogen production is less than $2/kg H2, making it competitive with other hydrogen production processes.

Low-carbon hydrogen

Low-carbon hydrogen production from CO2 capture and storage (CCS)     is more costly than green hydrogen production. The cost of CCS depends on the local CCS technologies used; generally, these costs will be higher than current renewable energy costs. In addition, the high cost of CO2 capture equipment results in a low overall energy yield during the production process.

Hydrogen can be produced electrochemically from water using existing commercial electrolysis technologies, but this process is thermodynamically challenging and requires a great deal of electricity input (25-60 kWh per KG H2)    . For this reason, the production of low-carbon hydrogen from electrolysis has to date been limited to small-scale applications. The use of renewable electricity to power large-scale electrolyzers is the most promising approach for enabling industrial-scale production of low-carbon hydrogen in the near future.

What we can get from 1 KG of Hydrogen ?

Electrolysis of water to produce hydrogen consumes 62 kWh of electricity per 1 kg of hydrogen produced. When compared to green hydrogen production from steam reforming, electrolysis consumes significantly more energy and has significantly higher environmental consequences. Furthermore, there is the potential for future increases in the price of electricity, which will negatively affect the viability of electrolysis-based hydrogen production.

Reference :

1. Advantages of green hydrogen: A fuel for the clean energy transition (https://www.innovationnewsnetwork.com/advantages-green-hydrogen-fuel-clean-energy-transition/22153/)     
2. The difference between green hydrogen and blue hydrogen (https://www.petrofac.com/media/stories-and-opinion/the-difference-between-green-hydrogen-and-blue-hydrogen/)     
3. Green Hydrogen (https://www.sciencedirect.com/topics/engineering/green-hydrogen )    
4. What is green hydrogen and why do we need it? An expert explains (https://www.weforum.org/agenda/2021/12/what-is-green-hydrogen-expert-explains-benefits/ )    
5. 50 shades of (grey and blue and green)     hydrogen (https://energy-cities.eu/50-shades-of-grey-and-blue-and-green-hydrogen/)     
6. Green hydrogen (https://en.wikipedia.org/wiki/Green_hydrogen )    
7. Electrification of the chemical industry—materials innovations for a lower carbon future (https://link.springer.com/article/10.1557/s43577-021-00243-9 )    
8. Electrification of the chemical industry—materials innovations for a lower carbon future (https://link.springer.com/article/10.1557/s43577-021-00243-9 )    
9. ECONOMICS (https://www.sgh2energy.com/economics#:~:text=COST%20COMPARISON&text=Green%20hydrogen%20produced%20through%20electrolysis,to%20higher%20natural%20gas%20prices.)