Hydrogen shows a lot of promise as a powerful, clean fuel source – as long as the process that creates it is also green. A new report shows how tough it might be to get to truly green hydrogen, while a new study removes a barrier to its creation.

According to a paper published today in the journal Nature Energy, by researcher Kiane de Kleijne from Radboud University and Eindhoven University of Technology in the Netherlands, the production of hydrogen more often than not leads to gains in atmospheric carbon dioxide (CO2). That's only in part because some of it comes from natural gas production.

There are greener ways to produce hydrogen such as using solar or wind to power the process that splits it off from water molecules, but De Kleijne argues that in such cases, the carbon footprint of creating those facilities needs to be considered. So does the fact that green power is most effective in places with lots of sun and wind like Africa or Brazil, which means that hydrogen produced there then needs to be transported to the rest of the world for use, which again, raises its carbon footprint.

"If you look at the entire life cycle in this way, green hydrogen often, but certainly not always, leads to CO2 gains," De Kliejne said. "CO2 gains are usually higher when using wind power rather than solar power. This will improve further in the future as more renewable energy will be used to manufacture the wind turbines, solar panels and steel for the electrolyzer, for example.”

Aquatic elephant in the room

Until that time, a new breakthrough in a popular hydrogen-production process called a proton-exchange-membrane (PEM) may help.

PEM is a water electrolysis process that splits off hydrogen from water molecules. Aside from the carbon cost of the electricity that powers the process, PEM is considered a green technology because its only output is oxygen, rather than carbon dioxide. The problem is that iridium is one of the only elements that can stand up to the harsh acidic environment in which water molecules are sheared apart. And iridium is very hard to find, as it's one of the rarest metals on Earth, so PEM facilities are difficult to create at scale.

Enter a new study from the Institute of Photonic Sciences (ICFO) in Spain, explained in detail in the following video.

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