Unveiling the Vibrant Palette Exploring the Colours of the Hydrogen Energy Rainbow

Introduction

Hydrogen is a versatile and abundant element that has the potential to revolutionize the way we produce and consume energy. As the most abundant element in the universe, hydrogen offers a clean, efficient, and sustainable alternative to traditional fossil fuels. In this section, we will explore the unique properties of hydrogen and its potential as an energy resource.

Hydrogen is a lightweight and highly reactive gas that can be produced from a variety of sources, including natural gas, biomass, and water. It can be used as a fuel in various applications, such as transportation, heating, and electricity generation. One of the key advantages of hydrogen is its ability to produce zero emissions when used in fuel cells, making it an attractive option for reducing greenhouse gas emissions.

As the world grapples with the urgent need for sustainable and clean energy sources, the concept of the hydrogen energy rainbow has emerged as a promising solution. At the heart of this rainbow lies green hydrogen, a fascinating and versatile energy carrier that has the potential to revolutionize the way we power our planet. Green hydrogen is produced through the process of electrolysis, using renewable energy sources such as wind or solar power to split water molecules into hydrogen and oxygen. This renewable and zero-emission fuel has garnered significant attention and is set to play a pivotal role in the transition towards a greener future.

The colours of the Hydrogen Rainbow

The hydrogen energy rainbow represents a spectrum of colours, each corresponding to a different production method and source of hydrogen. At one end of the rainbow, we find green hydrogen, which is produced using renewable energy sources. This clean and sustainable form of hydrogen has gained immense popularity due to its potential to decarbonize various sectors, including transportation, industry, and power generation. Beyond green hydrogen, there are other colours in the hydrogen energy rainbow, each with its own unique characteristics and potential applications.

Green Hydrogen is the energy vector of today, helping to meet our challenges in reducing the C02 emissions of industry, transport, electricity and much more. It is a clean fuel with almost limitless applications across many sectors, from fuelling transport to industry, and domestic homes.However, to use hydrogen for these applications it must be manufactured.  And unless we’re talking about ‘green hydrogen’ then the manufacturing process can be energy-intensive and have carbon by products.

So, what, and why are all the different colours of the hydrogen rainbow and what do they all mean? Hydrogen colours used represent the production method used and include black, brown, grey, blue, pink, turquoise, white and many more especially green. Hydrogen colours are used frequently when discussing various types of H2 projects their viability, and what they can do to help in broader efforts to decarbonise our economy. The "hydrogen energy rainbow" is a conceptual framework that represents the various colours associated with different methods of producing hydrogen, each with its own environmental impact and energy source. Here's a breakdown of the colours typically associated with the hydrogen energy rainbow.

• Green hydrogen, made with renewable electricity via electrolysis powered by renewable energy such as wind, solar or bio. It is the energy vector of today and is the best way to decarbonise society’s liquid and gaseous fuel needs. There are NO greenhouse gas emissions produced when making Green H2.

The benefits of green hydrogen are manifold. Firstly, it offers a clean and sustainable alternative to fossil fuels, reducing greenhouse gas emissions and mitigating climate change. Secondly, green hydrogen can be produced using abundant resources such as sunlight and water, ensuring long-term availability. Additionally, the versatility of green hydrogen allows for its integration into existing infrastructure, reducing the need for extensive modifications. Furthermore, the use of green hydrogen can enhance energy security by diversifying energy sources and reducing dependence on imported fossil fuels. Finally, the production and use of green hydrogen can drive economic growth and create job opportunities in the renewable energy sector.

• Blue hydrogen is produced mainly from natural gas using a process called steam reforming, which brings together natural gas and heated water in the form of steam. Perhaps be better described as ‘low-CO₂ hydrogen’ as the steam reforming process doesn’t avoid the creation of greenhouse gases. Manufactured in the same process as Gray Hydrogen, the only difference is that the CO2 produced alongside Hydrogen is Captured, utilised, or sequestered deep underground. If blue hydrogen is produced through autothermal reforming, whilst a more energy-intensive and expensive process it will enable up to 98% of CO₂ emissions to be captured.

• Grey hydrogen is essentially any hydrogen created from fossil fuels without capturing the greenhouse gases made in the process. CO2 is also a side product as there is combustion of natural gas. Grey hydrogen from steam reformed natural gas without CCUS accounts for around 71% of all hydrogen production today, while coal gasification makes up most of the rest. Grey hydrogen produced via SMR usually emits 9-12 kg of carbon dioxide per kilo of hydrogen. And because CCS is said to be able to only capture 70-85% of the CO₂ emissions from the SMR process, that would add a further 1.3-3.6kg of CO₂e to the total.

• Brown hydrogen or black hydrogen made from lignite (brown coal). Hydrogen has been made from coal through the process of ‘gasification’ for more than 200 years. This H2 is made using methods powered by bituminous (black) or lignite (brown) coal. The technique used for H2 production is highly polluting and releases copious carbon dioxide and carbon monoxide into the atmosphere, among other biproducts.

• 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.

• Purple, Pink, and Red Hydrogen – These hydrogen colours refer to H2 produced through electrolysis powered by nuclear energy. The purple form uses nuclear power and heat to split water via combined chemo thermal electrolysis. Pink uses the electricity produced by a nuclear plant to power water electrolysis. Red uses nuclear power thermal energy to power high-temperature catalytic water splitting. Pink hydrogen is still in its early stages of development, and its potential role in the hydrogen energy rainbow is yet to be fully explored.

• Yellow hydrogen made through electrolysis with solar power used to drive the Electrolysis of water to produce Hydrogen. Some consider it as electrolysed hydrogen made using power of mixed origin — i.e., the mix of renewable and fossil power flowing through the grid.

• White hydrogen is naturally occurring geological hydrogen found in underground deposits and created through fracking, although there aren’t viable exploitation strategies. In addition to green and pink hydrogen, white hydrogen has also garnered attention as a potential alternative. White hydrogen is produced using fossil fuels, but the carbon emissions generated during the production process are captured and stored underground through carbon capture and storage (CCS) technologies. This allows for the production of hydrogen with reduced carbon footprint. While white hydrogen may offer a transitional solution to decarbonization, it still relies on fossil fuels and does not provide a long-term sustainable alternative like green hydrogen.

Green Hydrogen is the unique energy pathway for decarbonisation

Whilst the rise of hydrogen in energy debates has been almost meteoric, there are many who are starting to highlight that there are many types of hydrogen and not all are key to our decarbonisation journey. Not all forms of hydrogen are equally clean and beneficial to climate change strategies.

Hydrogen has found itself hitting the energy headlines worldwide. Indeed, hydrogen is at the centre of many national, international, and corporate decarbonisation plans, however not all hydrogens are the same. Many energy and decarbonisation experts are critical of the wider hydrogen debate and warning that blue, grey and other colours of hydrogen are not as decarbonising as they appear on the surface.

Whilst the use of hydrogen in our energy spectrum is emission free, it is the production and transportation of several types of hydrogen that is giving rise to concern.

Green hydrogen (Green H2), as demonstrated in the GenComm project (nweurope.eu/gencomm) produced from renewable energy sources wind, solar and bio, is produced without greenhouse gas emissions so that it can then also be used without producing any emissions. However globally Green H2 only accounts for a small fraction of the global hydrogen production and use. Instead, Blue H2, hydrogen produced using fossil fuels such as natural gas, followed by carbon capture and storage methods is among those most found in national decarbonization plans with Green H2 playing a minimal role if any at all.

Companies and governments around the world are basing their decarbonisation plans on Blue Hydrogen.  Globally hydrogen is an important part of national energy infrastructure and decarbonisation plans, however what is not clear is that these decarbonisation pans, whilst a step in the right direction are not sufficient to carry us to our net zero goals.

In our transition to net zero we must communicate and highlight the differing decarbonisation gaps that exist with the range of hydrogen fuel colours. The H2 colour system used it today’s debates is too simplistic, does not convey the C02 content of the various production techniques and as such requires an update that refines the definitions. Essentially most people believe all hydrogen forms are the same and are unaware that not all hydrogen fuel is made in the same way.

Conclusion

These colours represent a spectrum of hydrogen production methods, ranging from highly carbon-intensive (grey) to completely clean and sustainable (green). The goal is to shift towards cleaner forms of hydrogen production to mitigate climate change and reduce dependence on fossil fuels. It is important to highlight that these terms and colours are used widely, without standard definitions and are commonly misused and creating confusion as a result.

To best understand what investments, projects, and opinions have to say about this alternative energy source, it’s best to know what the hydrogen colours really mean. After all, the technique used to produce the H2 is what determines how polluting it is. The use of this colourless gas (or liquid) typically results only in water vapor, without any carbon or greenhouse gas emissions. The same cannot be said about all methods of producing it.

As we plot a global transition to net zero the future of the hydrogen energy rainbow looks promising, with green hydrogen leading the way towards a sustainable and vibrant future. As renewable energy technologies continue to advance and become more affordable, the production of green hydrogen is expected to increase exponentially. The integration of green hydrogen into various sectors, such as transportation and industry, will help reduce greenhouse gas emissions and create a more sustainable energy system. Furthermore, ongoing research and development efforts aim to enhance the efficiency and cost-effectiveness of green hydrogen production, making it an even more viable option for widespread adoption.

Whilst green hydrogen holds immense promise as a clean and sustainable energy carrier. Its potential to decarbonize various sectors, reduce greenhouse gas emissions, and promote economic growth makes it a key player in the transition towards a greener future. While challenges and limitations exist, ongoing advancements in renewable energy technologies and supportive policies provide a pathway for the widespread adoption of green hydrogen.