An Analysis on Hydrogen Colours And Their Sustainability Potential

The Hydrogen Colour Wheel

Promising and Technologically Accessible Hydrogen Colours

Green hydrogen originates from renewable energy sources like wind or solar through a process known as water electrolysis, where an electrolyser splits water molecules into oxygen. This process generates between 0-2.5kg CO2 per kg H2,¹¹ depending on the source of electricity and efficiency of the electrolysis process, making it the cleanest form of hydrogen we have nowadays. Currently, the costs of green hydrogen are high ($3-$8 per kilogram H₂),¹² which can explain why it accounts for less than 0.1% of the world’s hydrogen production.¹³ To change that, green hydrogen production facilities need to be developed. In Saudi Arabia, the NEOM project aims to build the world’s largest green hydrogen plant. Only by expanding these structures can the production of green hydrogen become accessible on a global scale.

Yellow hydrogen is also developed using water electrolysis and uses electricity from the general power grid, which is typically a mix of fossil fuels, renewables, and nuclear. As power grids modernise, yellow hydrogen could become the cheapest form of renewable hydrogen in the medium term. Sweden is a great example to follow: approximately 99% of its energy mix is based on clean sources as of 2024.

Purple, pink, and red hydrogen can also be seen as clean energy sources, as they do not emit CO₂ during their production. Like green hydrogen, they are products of water electrolysis but powered by nuclear power and heat instead of renewable energy sources. This means that they are zero-carbon emitters if the nuclear source is emissions-free. These hydrogen colours are currently easier to access than green hydrogen, as the production facilities (nuclear plants) are more frequent. However, the price of production can vary significantly from one region to another depending on the political and public acceptance of nuclear plants. 

NEOM's Green Hydrogen Production Explained

 

Potentially Clean Hydrogen Colours in Early Development Stages

Orange Hydrogen targets the production of hydrogen out of plastic waste through pyrolysis, microwave catalysis and photo-reforming. These technical and chemical processes decompose plastic waste in the absence of oxygen using microwave energy and light-activated catalysts. The target is to extract hydrogen from plastic material to turn waste into a valuable energy source. This complex technology still requires fine-tuning and isn’t mature at industrial scale yet. Plastic varies a lot in its composition (polyethylene vs. PVC) making it difficult to extract enough hydrogen. Catalysts are an essential part to the production process but are currently very expensive, prone to errors and not optimised for large-scale production.

Turquoise Hydrogen is hydrogen produced from natural gas following a methane pyrolysis. Natural gas is decomposed into hydrogen and solid carbon at high temperatures. Because the carbon is solid, it isn’t released in the atmosphere but needs to be stored, which can cause additional logistical strains. Maintaining the high temperatures required for the production process is challenging and currently energy-intensive, as well as being expensive. Because this hydrogen still requires methane in its production phase, the supply chain leaks can undermine climate benefits. Turquoise hydrogen might need some time before proving itself as a clean solution, but could well become an alternative.

An insight into the production of turquoise hydrogen:

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What to Remember

An energy’s sustainable potential vastly depends on the production process that leads to its existence. Electric Vehicles are undeniably a way to reduce our greenhouse gas emissions, as they directly release far less carbon than cars running on natural gases. However, in order to have a definitive and positive impact on the environment, solutions to reduce our carbon footprint in the production process need further development. If the source of electric power or the batteries remain fossil fuels or other carbon-emitting materials in the long term, we are only hiding and delaying our problems, not finding solutions.

This same principle applies for the further development of hydrogen technologies. In 2023, the International Energy Agency (IEA) estimated that only 1% (!) of the global hydrogen production could be considered as clean. By 2030, projections from McKinsey claim that this number could rise to 30%. An important expansion of clean hydrogen-producing technologies will be vitally important if green hydrogen is to become a globally affordable option.

Thankfully, the technologies to develop clean hydrogen production already exist! The Solar Impulse Foundation has been monitoring and labelling innovative technologies like Ways2H’s Hydrogen Solution, where waste streams are converted into clean hydrogen without incineration. This thermochemical process produces syngas and leaves pure carbon, char, as a byproduct. The char is then collected and used as a fuel together with the remaining tail-gas to generate sufficient energy for the thermochemical conversion of the waste feedstock. This technology has been adopted by the UK to convert waste to fuel and serve as many as 1,600 fuel cell buses per day. By providing 500kg to 1 ton of renewable hydrogen fuel per day to heavy-duty trucks, lorries, or other Heavy Goods Vehicles, these vehicles will be able to cover 11,000 road kilometres!

The development of existing technologies in addition to the emergence of alternative solutions could also open new employment opportunities for workers forced to transit from the fossil fuel or oil industry to the field of clean energies, whether it be an operational or construction job for an electrolytic hydrogen facility. The UK government projects that its hydrogen strategy could lead to the creation of 64,000 jobs and generate over £7 billion in gross value added annually by the end of the decade.

ZeroAvia's Hydrogen-Powered Airplane, The First Zero-Emission Commercial Passenger Flight Between Rotterdam and London

 

Final Word

Stating that a technology has potential is one thing, but it is only by backing these words with concrete actions that important stakeholders can be convinced to invest in a transition to hydrogen solutions. Projects like Ways2H’s Hydrogen Solution or Climate Impulse could play a key role in proving to the world that hydrogen might be a path full of new opportunities from both an environmental-friendly and financial-improving perspective.

Pioneers are always the first to launch themselves on an adventure, but their acts aim to show that what was thought impossible at first can be achieved and reproduced on a larger scale!