What is Green Hydrogen and How is it Made?

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What is green hydrogen and how is it produced? It is often cited as one of the key elements in the global decarbonisation process, yet it still accounts for a tiny share of clean energy production.

Hydrogen has all the potential to be included in the energy sources of the future. The problem is that its production is still almost entirely done with CO2-emitting natural gas and coal plants.

In this JOurnal article we’ll take a look at how green hydrogen is produced and what the difference is between green, blue and grey hydrogen.


Our lifestyles are sustained by large amounts of watts, which are increasing every year. According to a report by the International Energy Agency (IEA) published in late 2019, global energy demand will grow by 25% to 30% by 2040. In a global economy dependent on fossil fuels such as coal and oil, this means an increase in greenhouse gas emissions and climate change.

Electrification is therefore one of the key steps towards achieving the decarbonisation goal that several governments and supranational entities, including the European Union, have set themselves. When electrification is not possible, the option would be to use clean energies such as green hydrogen. However, this technology is still in its infancy because production costs are still very high.


Green hydrogen is hydrogen produced from clean sources and currently accounts for only 1% of total hydrogen production. The European Commission intends to change this and has built an entire strategy to support hydrogen, putting it at the heart of the Green Deal and its substantial funding. For Brussels, the development of hydrogen technologies is key to achieving climate neutrality on the continent.

Hydrogen is the most abundant element in the universe and can be used as a particularly light and clean universal fuel. Its advantages are so numerous that some people envisage a hydrogen economy in the near future, i.e. energy consumption based entirely on hydrogen. However, there are still major problems relating to the availability of the element in nature and the level of technology development.


Molecular hydrogen is very scarce on our planet and is mainly found combined with other elements. The most common way to obtain green hydrogen is through the chemical process of electrolysis. To obtain hydrogen using this method, water is split into oxygen and hydrogen by an electric current, usually produced by photovoltaic systems. The photovoltaic industry is currently developing more efficient multi-junction cells to reduce the costs of this technology.


There are several ways of obtaining H2, with as many types (and colours) of hydrogen: green, blue, grey, violet and black. Black hydrogen is produced with a conventional diesel or coal-fired power plant, purple hydrogen with nuclear power. In Europe, only France produces purple hydrogen, while Germany and the UK, which also have nuclear power plants, prefer green hydrogen.

Hydrogen is called grey when it is produced through a chemical combination with methane gas. Blue hydrogen uses the same system, only the emissions are captured and stored underground, so they are not released into the atmosphere. Only green hydrogen is totally clean.


When the electricity used in electrolysis is generated from a renewable energy source, it is called green hydrogen.

Green has nothing to do with the colour of hydrogen (which is colourless and in gas form completely invisible), but merely serves to indicate the way in which it has been produced.

Some distinctions are already being made within green hydrogen: for example, electrolysis generated by a wind or photovoltaic system is greener than that produced by a biomass power plant. Although the latter is renewable energy, it still has an environmental impact.


Grey hydrogen is by far the most common and is produced by a method called steam reforming. The waste from this process contains CO2. According to studies, steam reforming produces about 9.3 kg of CO2 for every kilogram of hydrogen produced.


Blue hydrogen is made from methane, but the plant has a carbon capture and storage (CCS) system. Its proponents see it as a necessary step until technologies allow a full transition to green hydrogen. However, at least 10-20% of the CO2 generated always escapes capture systems, so blue hydrogen cannot be considered a clean, low-carbon form of energy.

The European Commission is one of the bodies that has given it a role in the transition under the hydrogen support programme. The UK also made a similar choice in August 2021. This decision was widely criticised by the green hydrogen industry and led to the resignation of the chairman of the UK Hydrogen Association.


What is green hydrogen used for? As a clean fuel, it has many uses, from cars and buses to space rocket propulsion. It can form the basis of both batteries and internal combustion systems.

Hydrogen batteries are an opportunity to convert hydrogen energy directly into electricity. They can be used for both stationary and mobile power generation.

As a fuel, hydrogen is less interesting because in contact with air it produces nitrogen oxide, a polluting gas. The engines are therefore not considered zero-emission, and vehicles would not be allowed to circulate in areas of the city where only clean vehicles are allowed.


Like any other form of energy, green hydrogen has advantages and disadvantages of which it is important to be aware. The positive aspects are:

The negative aspects are:


As mentioned above, Europe wants to boost the decarbonisation of H2 production, identifying blue and green hydrogen as two of the cornerstones of the Green Deal. In a Q&A published in July 2020, the Commission pointed out how falling costs of renewables and technological developments are enabling the expansion of green hydrogen use in sectors where fossil fuels need to be replaced.

Brussels distinguished three phases for the development of the clean hydrogen economy.


In the first phase, from 2020 to 2024, the aim is to decarbonise all existing hydrogen production and promote new applications. In this phase, at least 6 Gigawatts of green hydrogen electrolysers will have to be installed in Europe. Currently, production stands at 1 Gigawatt.


In the second phase (2024-2030), hydrogen will become part of an integrated energy system. The aim will be to install at least 40 Gigawatts of green hydrogen electrolysers by 2030 and to increase production to 10 million tonnes. In this phase, the use of green hydrogen will be extended to sectors such as steel production, heavy transport, railways and some segments of maritime transport.


From 2030 to 2050, renewable hydrogen technologies are expected to reach maturity, with large-scale deployment to decarbonise all sectors where the use of other alternative energies is unsuitable or more expensive.


According to the EU, investment in hydrogen will play a crucial role in the recovery from the COVID-19 pandemic. Indeed, the Commission’s Recovery Plan highlights the need to unlock investment in value chains and clean technologies to foster sustainable growth.

Europe’s hydrogen research sector is at the forefront and well positioned for global development. Estimates of cumulative investment in green hydrogen by 2050 range from 180-470 billion euros, with an expanding labour market of up to 1 million direct and indirect jobs.

According to estimates cited by Brussels, renewable hydrogen could cover 24% of global energy demand by 2050, with annual sales in the region of EUR 630 billion.

To date, neither renewable hydrogen (green) nor hydrogen produced from fossil fuels with CO2 capture systems (blue) can compete with the production costs of hydrogen generated from fossil fuels (grey). The estimated costs of green hydrogen range between €2.5 and €5.5 per kilogram, compared to €2/kg for blue hydrogen and €1.5/kg for grey hydrogen.

Blue hydrogen is therefore cheaper than green hydrogen, but the green industry claims investments on the latter should be much greater.

However, the costs of green hydrogen are falling rapidly. Over the past 10 years, electrolyser costs have fallen by 60% and are expected to halve by 2030. The sector surely promises interesting developments. If you want to keep up to date with news about alternative energy sources, keep following our JOurnal.

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