Hydrogen has more than one name. And although it is an odorless, tasteless and colorless gas, more shades of it have been talked about for a long time. With their help, we can distinguish methods of hydrogen production, and more specifically, highlight the importance of the energy source used in the process. Are you curious what are the different hydrogen colors? Then we invite you to read on!
Poland is a big player in the global hydrogen market
Few people know that Poland is one of the leaders in hydrogen production, ranking 3rd in Europe and 5th globally. Over a million tons of this unique gas is produced in the country every year, which corresponds with about 10-15% of the total hydrogen production on the Old Continent. Observing these statistics, one could assume that the energy transformation of the Polish economy, the increase in hydrogen use in all its sectors, and thus meeting the restrictive climate targets, is only a matter of time. Unfortunately, it is not that simple, as the current domestic production is mostly based on fossil fuels. As a result, the produced hydrogen has a high level of carbon dioxide emissions into the atmosphere. Hydrogen produced in this way is referred to as gray hydrogen.
Where did the colors of hydrogen come from?
We all know very well that under standard conditions hydrogen is a non-toxic, tasteless, odorless, and… colorless gas. Nevertheless, when talking about hydrogen, we distinguish its specific colors. What is the source of the new nomenclature?
The most important indicator for the use of hydrogen in fuel cells is its purity level (standard 5.0). This is because even the smallest traces of impurities can damage the performance and durability of a fuel cell system, particularly in hydrogen vehicles (BEV). Therefore, the method of extraction itself has so far been relegated to the background. However, due to the current emission reduction targets in every sector of the economy, not only the purity of hydrogen but also its origin takes on particular importance. To be more precise, the origin of the energy used to produce the fuel of the future.
As statistics show, currently about 96% of the total production of hydrogen in the world is based on conventional fuels, and 4% consists of water electrolysis. It should be noted that only about 1% is electrolysis, which uses energy from renewable sources, the most environmentally beneficial method in which we obtain completely zero-emission green hydrogen. This is another of the hydrogen shades highlighted. Apart from it and the grey hydrogen, the rich palette also includes blue, black, brown, pink, turquoise, yellow, and white hydrogen. Today we will try to introduce them in a little more detail.
Gray hydrogen
Produced in the steam reforming of hydrocarbons – SMR (Steam Methane Reforming) process, which is characterized by high emissions (estimated 9-12 kg CO2/kg H2). Steam reforming is one of the most important technological processes which results in obtaining synthesis gases for the production of methanol, ammonia, and hydrogen.
Synthesis gas is a mixture of carbon monoxide, hydrogen, and carbon dioxide which is produced on a mass scale and is currently one of the most important sources of hydrogen. Natural gases, coal, and even some waste fractions of crude oil processing can be used to produce it. Hydrogen obtained in this way finds its application mainly in refineries (petrochemical industry), food, nitrogen, and metallurgical industries. Its annual production in the world already exceeds 55 million tons.
The emphasis on using natural gas (methane) in the SMR process is no accident. It is a raw material that currently provides high efficiency, resource sufficiency and relatively low cost compared to other methods using conventional fuels. The reforming process itself involves the reaction of methane with steam at a temperature of 700-1000°C in the presence of a suitable metallic catalyst. Thus, it requires significant energy input and harms the environment due to its emissivity. Therefore, CO2 capture methods are constantly being developed.
Blue hydrogen
The result is the separation of blue hydrogen. This is often referred to as the most economically beneficial stage in the energy transition from grey to green hydrogen. Blue hydrogen is produced using fossil fuels, with carbon capture methods used to reduce pollution levels in the process. The most commonly used technologies are CCS (Carbon Capture Storage) and CCU (Carbon Capture Utilization).
Until recently, blue hydrogen was thought to be nearly emission-free (enabling up to 95% decarbonization). However, a study published in the middle of last year, taking into account the full life cycle of blue hydrogen, proves that its production can generate even higher emission rates than burning fossil fuels, making its use fail to meet current reduction requirements (we wrote more about it here).
Black and brown hydrogen
Black hydrogen and brown hydrogen are much less commonly distinguished in the literature. Again, both colors refer to hydrogen produced from conventional fuels. These distinctions are most often used when we want to emphasize what specific raw material was used in the production process. Black hydrogen is hydrogen extracted from synthetic gas using coal. Brown, on the other hand, refers to production methods based on lignite.
Turquoise hydrogen
Obtaining turquoise hydrogen by pyrolysis is a relatively new and still developing production method. As in the case of gray and blue hydrogen, it uses fossil fuels as the base materials. However, in this case, the process is carried out not by burning them, but with the heat generated by electricity.
The main products of methane pyrolysis are hydrogen and carbon – obtained in solid form, which eliminates the need to capture and store it. If only electricity from RES was used to carry out the process, it would have almost zero emissions. The new method is therefore an interesting field for further exploration.
Green hydrogen
The most desirable color of hydrogen in the perspective of decarbonization of the global economy. At the same time, the most supported by the new policy of the European Union, which focuses on financing projects that will enable the increase of green hydrogen production capacity in member states at the turn of the next two decades.
Green hydrogen is produced in the process of electrolysis, which uses only electric energy coming from renewable sources. Produced in this way, it is completely zero-emission and has a high potential for use in all areas of the economy, even the most difficult ones.
Electrolysis separates water into its basic components, hydrogen, and oxygen. During the process, under the influence of an electric voltage, the bond between the two is broken. At present, the efficiency of the process oscillates between 50-70%, but the technology is constantly being developed and its efficiency improved.
Already today, the EU’s strategy is to achieve 6 GW of installed electrolyzer capacity and production of one million tons of green hydrogen by 2024, and even 40 GW of installed capacity and production of 10 million tons by 2030. Experts predict that thanks to the investments already announced, this target will be exceeded in 2027.
Pink hydrogen
Often alternately referred to as purple or red hydrogen. It is produced by nuclear-powered electrolysis. Using the atom to produce hydrogen is an interesting and certainly promising concept. Already today, experts point to its low emissions, target cost-effectiveness, and emphasize that it will be able to supplement production from renewable energy sources, and thus meet the growing demand of industry and power generation.
In addition to the hydrogen colors discussed, yellow hydrogen, produced by electrolysis using direct solar energy and nanotechnology, and white hydrogen are often highlighted. The multitude of hues in this unique hydrogen palette already reinforces the belief that the potential of the new fuel is enormous and, more importantly, will be developed even more strongly in the years to come.
