Hydrogen is the most abundant element in the universe. Its structure is extremely simple, consisting of one proton and one electron. It is commonly found bonded as H2 on Earth but is rare in its pure gaseous form. Despite this, hydrogen is increasingly seen as a game-changing fuel that could help transform the global energy landscape. This article will explore the different types of hydrogen and their potential roles in creating a sustainable energy future.
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The Importance of Hydrogen in Clean Energy
Fossil fuels have powered industry, commerce, and our daily lives for decades. However, the negative environmental impacts of these energy sources have driven the search for alternatives.
Hydrogen is not an energy source but an energy carrier capable of storing and delivering clean energy. Unlike fossil fuels, burning hydrogen only produces water and energy without releasing harmful carbon emissions.
Hydrogen is also highly effective for energy storage, boasting a better energy-to-weight ratio than traditional fuels like gasoline and natural gas. It is well-suited for industries where decarbonization using solar or wind power is difficult. Hydrogen is crucial as an energy storage solution and a chemical feedstock, making it essential for many sectors. Its potential to boost energy security, enhance air quality, combat climate change, and support industrial strategy is significant.
However, hydrogen production is often expensive, technically challenging, and inefficient. Most commercial hydrogen is still derived from fossil fuels, limiting its environmental benefits. Despite these hurdles, hydrogen holds enormous promise for the future of clean energy.1
The Different "Colors" of Hydrogen
Though hydrogen is colorless, different types of hydrogen are classified by colors to denote the energy source or production method used. The most common types are black, grey, green, and blue hydrogen, but other varieties also exist.
Grey, Black, and Brown Hydrogen
Grey, black, and brown hydrogen are all produced using fossil fuels through steam reforming. Grey hydrogen is derived from natural gas, while black and brown hydrogen come from coal. These methods release significant carbon emissions, making them environmentally damaging.2
Some companies, such as Air Products, Shell, and BP, produce grey hydrogen on a large scale.3 Many are investing in greener alternatives, but most hydrogen production relies on fossil fuels.
Green Hydrogen
Green hydrogen is produced using renewable energy sources through electrolysis, which splits water into hydrogen and oxygen. As it does not rely on fossil fuels, green hydrogen is far cleaner than its grey, black, or brown counterparts. While green hydrogen production is currently more costly and technically challenging, it has the potential to significantly decarbonize industries and help achieve net-zero emissions significantly. Realizing full-scale commercial production of green hydrogen is a key aim for multiple stakeholders in the energy sector and related fields such as transportation.2
There have been some key developments in the field of green hydrogen in recent years. Global production reached 109,000 tonnes in 2022, a 41% increase over production in 2021. AMEA Power are developing a 10,000 MW project in Egypt, supporting the government’s long-term vision of the nation as a green energy production hub.3
First Hydrogen is working on zero-emission fleets with modular EV capability and hydrogen fuel cell technologies as well as advanced hydrogen refueling stations. Lhyfe, a European group, has announced plans to create floating hydrogen production plants that can be used to make green hydrogen at sea.3
Siemens Energy has developed an innovative technology using Proton Electron Membrane (PEM) electrolysis to produce green hydrogen efficiently and cheaply. 100-2000 kg of green hydrogen can be generated using the company’s technology, with only 10 liters of water consumed per kilogram of green hydrogen produced.3
Blue Hydrogen
Blue hydrogen is similar to grey hydrogen, with one key difference: the carbon emissions produced during steam reforming are captured and sequestered using carbon capture and storage in underground locations. While it is considered carbon neutral due to no atmospheric emissions release, around 10-20% cannot be captured.2
While not ideal for environmental friendliness, it is nevertheless a better option than grey, black, or brown hydrogen. Some interesting developments have been announced in the past few years, such as Air Product’s plans to build Europe's largest blue hydrogen plant.4 The plant is expected to be operational by 2026.
White or Gold Hydrogen
White hydrogen, also called gold hydrogen, is naturally occurring and can be found in underground reservoirs.
The U.S. Geological Survey estimates that billions of megatons of white hydrogen exist, which could supply global energy needs for centuries. However, extracting this pure hydrogen is complex and potentially expensive, particularly when deposits are located in hard-to-reach areas like the deep sea.
The Bill Gates Breakthrough Energy Ventures firm recently announced that it would be investing in US start-up Koloma’s US plans to produce white hydrogen. Companies like Getech are exploring potential deposits in Togo and South Africa. Jacque Pironon’s team has discovered a large deposit of natural hydrogen in France.5
Other Hydrogen Types
Beyond these primary colors, other forms of hydrogen also exist. Turquoise hydrogen uses methane pyrolysis to produce hydrogen and solid carbon, eliminating the need for carbon capture and storage. Pink hydrogen is produced using nuclear power, while yellow hydrogen refers to hydrogen generated from solar power or a mix of renewable energy sources.
Biomass can also produce hydrogen, producing fewer emissions than fossil fuel-based methods.
The Road Ahead for Hydrogen
Hydrogen has the potential to transform energy, industry, and transportation, helping to reduce carbon emissions and address climate change significantly. Despite the technical and economic challenges today, hydrogen's enormous benefits outweigh these drawbacks, driving further innovation and investment.
With continued development in production technologies and infrastructure, hydrogen could be a key component in transitioning from harmful fossil fuels to a cleaner, more sustainable future.
References and Further Reading
- Hector, G. (2021). Why is hydrogen important to the Energy Transition? - Westwood. [online] Westwood. Available at: https://www.westwoodenergy.com/sectors/energy-transition/why-is-hydrogen-important-to-the-energy-transition [Accessed 5 Nov. 2024].
- Marchant, N. (2021). Grey, blue, green – why are there so many colours of hydrogen? [online] World Economic Forum. Available at: https://www.weforum.org/agenda/2021/07/clean-energy-green-hydrogen/.
- King, C. (2023). Top 10: Hydrogen Companies. [online] energydigital.com. Available at: https://energydigital.com/articles/top-10-hydrogen-companies.
- Air products to build Europe’s largest blue hydrogen plant and strengthens long-term agreement (2023). https://www.airproducts.co.uk/company/news-center/2023/11/1106-air-products-blue-hydrogen-plant-europe-and-exxonmobil-long-term-agreement.
- Woollacott, E. (2023). Could there be a gold rush for buried hydrogen? BBC News. [online] 12 Dec. Available at: https://www.bbc.co.uk/news/business-67541581.
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