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Current Hydrogen Production Methods

[Mohammed bin Rashid Al Maktoum Solar Park is a solar park spread over a total area of 77 km2 in Seih Al-Dahal, about 50 kilometers south of the city of Dubai]

- Overview

Although abundant on earth as an element, hydrogen is almost always found as part of another compound, such as water (H2O) or methane (CH4), and must be separated into pure hydrogen (H2) for use in fuel cell electric vehicles. Hydrogen fuel combines with oxygen from the air through a fuel cell, creating electricity and water through an electrochemical process. 

Hydrogen can be produced using diverse, domestic resources -- including fossil fuels, such as natural gas and coal (with carbon sequestration); nuclear energy; and other renewable energy sources, such as biomass, wind, solar, geothermal, and hydro-electric power -- using a wide range of processes.

About 95% of the hydrogen produced in the United States comes from natural gas. It’s created using steam methane reforming, which basically uses high temperatures to convert steam and methane into hydrogen gas and carbon dioxide. 

The challenge is, global demand for hydrogen and its emerging applications could increase by a factor of ten, surpassing our current infrastructure for producing and delivering hydrogen.  

- Current Production Methods

Hydrogen, in itself, is a clean fuel. Manufacturing hydrogen fuel, however, is energy-intensive and has carbon byproducts. What is now called brown hydrogen is created through coal gasification. The process for producing grey hydrogen from natural gas throws off carbon waste. 

Although there is no universal naming convention for hydrogen, almost everyone can agree on the fact that the majority of today’s H production is either green, blue or grey. Unlike green hydrogen production, which uses electricity from renewable sources to split water into its chemical components -- hydrogen and oxygen -- gray hydrogen is derived directly from fossil fuels, typically by splitting natural gas into its own chemical components, carbon and hydrogen. Blue hydrogen is derived from fossil fuels in a similar fashion as gray, but paired with sequestration to capture the carbon emissions this form of hydrogen production generates. 

Blue hydrogen uses carbon capture and storage for the greenhouse gases produced in the creation of grey hydrogen. Green hydrogen production -- the ultimate clean hydrogen resource -- uses renewable energy to create hydrogen fuel. For example, water electrolysis used to produce long-duration hydrogen energy storage requires a lot of energy. That energy could come from renewables.

Both grey and blue hydrogen are currently cheaper to produce than green hydrogen, so some countries, including China, are using gray hydrogen to prompt the development of hydrogen-compatible infrastructure. The line of thinking is that this approach will enable the development of pipelines and other infrastructure compatible with hydrogen, so that when green hydrogen does become more widely available, China will be ready for widespread distribution. But in environmentally-minded regions such as the EU, gray and blue hydrogen lack social acceptance.

Green or low-carbon hydrogen will become cost-competitive by 2040, given increased scale and lower costs of renewables, along with higher costs for producing brown, grey and blue hydrogen. Utilities will need to include all colors of hydrogen in their scenario planning, especially those with zero emissions commitments.


- Beyond Blue, Green, Brown and Grey

As with many things in life, the hydrogen world is not as simple as it first appears. We also have turquoise hydrogen. Turquoise hydrogen is a by-product of methane pyrolysis, which splits methane into hydrogen gas and solid carbon. Some consider that this makes turquoise hydrogen a low-emission hydrogen choice -- but this depends on the energy-hungry thermal process being powered with renewable energy and the carbon being permanently stored. 

After this, the colours start to get a bit blurred. Pink hydrogen also finds its place in the spectrum, referring to hydrogen generated through electrolysis powered by nuclear energy. Yellow hydrogen is used by some to refer to hydrogen made through electrolysis with solar power, while confusingly, others consider it as electrolysed hydrogen made using power of mixed origin — i.e. the mix of renewable and fossil power actually flowing through the grid. 

Finally, white hydrogen is naturally-occurring geological hydrogen found in underground deposits and created through fracking, although there aren’t viable exploitation strategies.


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