Global Power Leader Cummins Explains the Hydrogen Rainbow

Dec 9, 2021 2:25 PM ET
abstract picture with rainbow colors and hexagons


Perhaps you’ve heard of blue hydrogen, green hydrogen, or even pink hydrogen, but what do these multi-hued descriptors actually mean?

The colors that make up the hydrogen rainbow say a lot about how various forms of hydrogen are produced and the impact each could have on the planet. Here’s a quick look:

  • GREY: Grey hydrogen is created from natural gas, most commonly methane, through a process called steam methane reformation. While it is the most common form of hydrogen production, the greenhouse gases (GHGs) made in the process aren’t captured.
  • BLUE: Blue hydrogen uses steam methane reforming, but the carbon dioxide (CO2) produced as a byproduct is captured and sequestered underground.  It is a source of clean hydrogen with a low carbon content.
  • TURQUOISE: Turquoise hydrogen is produced via a process called methane pyrolysis. Its primary outputs are hydrogen and solid carbon. It has no proven impact at scale yet but has potential as a low-emission solution if scientists discover ways to power the thermal process with renewable energy and properly use or store the carbon byproduct.
  • PINK: Pink hydrogen taps into nuclear energy to fuel the electrolysis required to produce it. The high temperatures of nuclear reactors produce steam that can be used for electrolysis or fossil gas-based steam methane reforming in other forms of hydrogen production.
  • BROWN: Brown hydrogen relies on the gasification of coal to produce hydrogen. This process releases harmful carbon emissions that can have a long-lasting negative impact on the climate.
  • GREEN: Green is the only hydrogen produced with zero GHGs. Made using renewable energy sources like solar, wind and hydropower to electrolyze water, it produces only hydrogen and oxygen, meaning zero CO2 is emitted.

Green hydrogen makes up just a small percentage of current hydrogen production. But as new advances in green hydrogen are made, the price is expected to come down, so it will become more common across the globe.

The emphasis on reducing carbon emissions has led many power leaders, including Cummins, to invest and innovate in green hydrogen production. The company is building on its industry-leading electrolyzer technology to reduce the cost of hydrogen fuel cells and make it easier to get green power solutions in customers’ hands.

When it comes to the world’s climate challenges, green hydrogen could be the gold at the end of the hydrogen rainbow.