We have introduced you to the color classification of carbon (click here to review the article). In fact, hydrogen, widely used and considered one of the important new energy sources to achieve carbon neutrality, has a "color spectrum " similar. - Of course, hydrogen itself is colorless, and it is mainly found on Earth as chemical compounds in water and fossil fuels, which need to be "extracted" using hydrogen production technology. To easily distinguish between them, researchers around the world have assigned various "colors" to hydrogen based on how it is produced and its environmental impact. Here are a few common color terms for hydrogen.
Brown hydrogen, sometimes called "black hydrogen", is a color reminiscent of severe air pollution important. Although hydrogen is a clean fuel, if it is produced through the gasification of fossil fuels, especially coal, it will certainly create a lot of carbon emissions in the process. According to Wood Mackenzie, an energy research and consulting agency, producing 1 kg of brown hydrogen produces 20 kg of carbon dioxide, the most harmful type of hydrogen production.
Gray hydrogen is hydrogen produced by reforming distillation of natural gas, methane, etc. This production method has low requirements in terms of technology, equipment, space and cost, so the majority of hydrogen currently on the market is gray hydrogen, accounting for about 95% of global hydrogen production. Compared with brown hydrogen, the carbon emissions of gray hydrogen are lower, but the production of 1 kg of gray carbon can still yield about 9~10 kg of carbon dioxide emissions, which is only better than that of brown hydrogen.
Green hydrogen is somewhat like an "evolved" version of gray hydrogen, with the same production method, except that green hydrogen capture, utilization and storage (CCUS) technologies capture and Store carbon dioxide promptly after it is produced. However, gray hydrogen produces not only carbon dioxide but also unburned methane. Carbon capture technology cannot avoid releasing large amounts of lost methane, so the total greenhouse gas emissions of green hydrogen remain high.
Cyan Hydrogen is hydrogen produced by pyrolysis of natural gas . Because there is no oxygen in the production process, the carbon created with hydrogen is black carbon in solid form, which can be used for industrial purposes or to improve soil quality. This production process does not emit any greenhouse gases and does not require carbon capture technology, so turquoise hydrogen is considered much lower carbon than green hydrogen. However, it is important to note that the extraction and transportation of natural gas, the raw material for manufacturing, can still cause carbon emissions.
Like As the name suggests, green hydrogen is a sustainable and clean energy source, and its production method typically uses renewable energy to generate electricity for water electrolysis to produce hydrogen and oxygen, of which hydrogen is extracted as fuel and the oxygen is released into the atmosphere, achieving zero carbon dioxide emissions from the source. Currently, green hydrogen accounts for only 0.1% of total hydrogen production due to high production costs, but it is believed that its cost will gradually decrease with its popularity in the future.
Pink hydrogen, also known as red hydrogen or purple hydrogen, is similar to green hydrogen in that it is also produced by electrolysis. However, pink hydrogen does not use renewable energy sources such as solar, wind and hydroelectricity as energy like green hydrogen, but uses nuclear thermal power as energy to catalyze water at high temperature. This method can not only achieve zero carbon emission in hydrogen production, but also effectively expand the use of nuclear energy, this is one of the important exploration directions for large-scale hydrogen supply in the future.
There are two explanations for yellow hydrogen, one is branch of green hydrogen, refers to the use of solar energy for electrolysis to produce hydrogen, in this context, the main challenge of yellow hydrogen is how to reduce the cost of photovoltaic power generation and how to recycle the solar panels at the end of their life cycle; The second is to describe the electrolytic production of hydrogen produced by a mixture of renewable energy and fossil fuels, where the carbon footprint of yellow hydrogen fluctuates with different energy ratios.
White hydrogen is natural hydrogen found in underground mines, and these natural "hydrogen ores" can be mined by drilling. Because it is available through natural geological and chemical phenomena, white hydrogen is theoretically a renewable energy source and does not have as high production costs as green hydrogen. According to predictions by many agencies, white hydrogen can be continuously extracted at a low cost of less than 1 USD/kg. Of course, it is important to be aware of the environmental impact of the mining method itself.
Golden Hydrogen is also used to describe natural hydrogen, but compared to golden hydrogen, golden carbon has a more "artificially cultivated" meaning, referring to people actively injecting oil-eating microorganisms into oil reservoirs depleted crude, spurring abandoned oil fields to produce hydrogen, and then recovering the "cultivated" hydrogen. This approach provides another low-cost way to produce hydrogen, as well as reusing many abandoned and stranded oil fields, creating a new revenue stream for heavy industry companies.
Other things you need to know
● Word conversion fossil fuels to hydrogen could help us significantly slow the rate of climate change, and in addition to reducing carbon emissions, developing hydrogen could create more jobs, improve energy security, and promote promote sustainable global development. The Hydrogen Council estimates that if the world focuses on scaling up over the next decade, hydrogen could meet 18% of the world's energy needs by 2050, providing energy for more than 40 billion passenger cars, 200,000 trucks and more. and reduce CO2 emissions by about 20% to limit global warming.
● Among the many hydrogen production methods, gray hydrogen is currently trending the mainstream of the market, but this method will bring a lot of carbon emissions, and the carbon emissions of gray hydrogen production are equivalent to the carbon emissions of Indonesia and the UK combined. Therefore, not all projects involving the use of hydrogen are equivalent to "green and low carbon". Gray hydrogen needs to be combined with carbon capture technology and a variety of cleaner energy supplies.
● Green hydrogen is a truly green fuel, but it costs Its production is currently higher than most other colors. The good news is that with the decreasing cost of renewable energies and the investment and development of green hydrogen infrastructure in various countries, the threshold for green hydrogen production will gradually be lowered. Analysis by the International Energy Agency (IEA) says the cost of producing hydrogen from renewables could fall by 30% by 2030. Wood Mackenzie forecasts show green hydrogen willaccounting for about a fifth of the total hydrogen market by 2050.
● International cooperation is essential to accelerate the development of clean hydrogen worldwide world and to achieve the common goal of carbon neutrality, countries around the world need to strive to establish common development standards, actively promote investment in various types of clean hydrogen infrastructure, and share experience. practical experience and effective engineering knowledge, while scaling hydrogen energy in a coordinated way.