The colours that make up the hydrogen rainbow tell us a lot about how each specific kind of hydrogen is produced.
Hydrogen might be the most abundant element in the universe, but it doesn’t exist on its own. Instead, it is produced through a number of processes that each yield different types of energy, which come with their own sets of benefits, byproducts and uses. The production method is what gives each kind of hydrogen its colourful moniker — though there is no universal naming convention, so definitions can change over time and vary between countries.
- Grey hydrogen: Grey hydrogen is created from natural gas, most commonly methane, through a process called steam methane reformation. While it is currently the most common form of hydrogen production, the greenhouse gases made in the process aren’t captured.
- Blue hydrogen: Blue hydrogen relies on the conventional process of steam methane reforming, but the carbon dioxide produced as a byproduct is captured and sequestered underground. It is a source of clean hydrogen with a low carbon content.
- Turquoise hydrogen: One of the newer colours to join the hydrogen spectrum, turquoise hydrogen is produced via a process called methane pyrolysis. Its primary outputs are hydrogen and solid carbon. While turquoise hydrogen has no proven impact at scale yet, it has potential as a low-emission solution if scientists can find ways to power the thermal process with renewable energy and properly use or store the carbon byproduct.
- Pink hydrogen: Pink hydrogen taps into nuclear energy to fuel the electrolysis required to produce it. The high temperatures of the nuclear reactors provide an additional benefit — the extreme heat produces steam that can be used for electrolysis or fossil gas-based steam methane reforming in other forms of hydrogen production.
- Brown/black hydrogen: If green and blue hydrogen hold the key to cleaner hydrogen production, brown or black hydrogen are the exact opposite and the most environmentally damaging. Relying on gasification of coal to produce hydrogen, this process releases harmful carbon emissions that can have a long-lasting impact on our climate.
- Green hydrogen: Amidst the hydrogen rainbow, green hydrogen is the only variety produced with zero harmful greenhouse gas emissions. It is created using renewable energy sources like solar, wind and hydropower to electrolyze water. The resulting reaction produces only hydrogen and oxygen, meaning zero carbon dioxide is emitted in the process. While the benefits of green hydrogen are significant, its production is more expensive today. Consequently, green hydrogen makes up just a small percentage of current hydrogen production. But as new advances and innovations in green hydrogen are made, the price will come down, and it will hopefully become common across the globe.
Hydrogen has been used as fuel for more than two centuries. Today, thousands of vehicles and machines around the world are powered by hydrogen fuel cells. The emphasis on reducing carbon emissions and working towards a greener, sustainable future has shifted the focus of many power leaders, including Cummins, to investment and innovation in green hydrogen production. It could prove to be the gold at the end of the hydrogen rainbow.
The cost of production has slowed the wide-scale adoption of hydrogen power. Many leaders in the power industry are now putting an emphasis on making hydrogen fuel cells more readily available to consumers. Cummins is building on our industry-leading electrolyzer technology to reduce the cost of hydrogen fuel cells and make it easier to get green power solutions into our customers’ hands. Source