"Blue Hydrogen" Has Been Touted As A Clean Fuel. In Fact, It May Be Even Dirtier Than Coal


Dr. Katie Spalding

Katie has a PhD in maths, specializing in the intersection of dynamical systems and number theory.

Freelance Writer


If that gas station was green instead it wouldn't be a problem. Image credit: Scharfsinn/

As you may have heard, the planet is burning and catastrophe is looming. Humanity’s only hope is to make some big changes to the way we live, and fast. Unfortunately, a new analysis published in Energy Science and Engineering has suggested that one of the major ways we might have tackled the climate crisis – using so-called “blue” hydrogen – may not be as green as we thought. In fact, according to the study, the carbon footprint of this purported “clean” energy source may be as much as 20 percent more than simply burning natural gas or coal.


Hydrogen has been touted by scientists and governments alike as an answer to the world’s energy and environmental crisis. After all, it’s got a lot going for it. Unlike fossil fuels, it doesn’t release harmful carbon emissions when it burns – just water – and it’s not like we’re running out any time soon either, since it’s literally the most abundant substance in the universe. In fact, there’s really only one major problem with hydrogen: actually getting hold of it.


While it accounts for about three-quarters of the mass of, well, everything in existence, here on Earth hydrogen very rarely turns up on its own. Instead, it has to be extracted from water molecules – a process that leaves us in the strange situation of having 96 percent of our “clean” alternative to fossil fuels being produced by fossil fuels. 

“Most of the hydrogen in the U.S. and Europe comes from natural gas, using steam and pressure to convert the methane from natural gas into a so-called ‘gray’ hydrogen and carbon dioxide,” explained Robert Howarth, co-author of the study. “In the past, no effort was made to capture the carbon dioxide byproduct of gray hydrogen, and the greenhouse gas emissions have been huge.”

To combat this, the fossil fuel industry has recently been promoting what it calls “blue hydrogen” – it’s made in essentially the exact same way, but more effort is made to catch the resulting carbon dioxide. On the face of it, that may sound like problem solved, but in practice only 85 to 90 percent of the CO2 is actually captured. If blue hydrogen becomes the future, the paper warns, it can “only [work] to the extent it is possible to store carbon dioxide long-term indefinitely into the future without leakage back to the atmosphere.”

Blue hydrogen may be a cleaner alternative, but it’s not much cleaner – it releases maybe 10 percent fewer emissions than its gray counterpart, which, the paper notes, is “hardly emissions free”. When you take into account the “fugitive” methane emissions which are an unavoidable part of dealing with natural gas, blue hydrogen ends up with a carbon footprint 20 percent higher than just burning that same natural gas directly. It releases 60 percent more emissions than burning diesel oil.


“[The energy] industry promotes blue hydrogen as a solution,” said Howarth. “Unfortunately, emissions remain very large.”


There is an alternative to gray and blue hydrogen: green hydrogen, which is produced by water electrolysis and renewable energy. But it’s a tiny sector, accounting for just one-twenty-fifth of the hydrogen in use today, and it’s comparatively expensive. While gray hydrogen costs about a dollar per kilogram and blue hydrogen comes in at around $2 for the same, green hydrogen can currently cost more than $4 per kilogram. But according to Howarth, that’s just the price we must pay for a carbon-free future.

“The best hydrogen, the green hydrogen derived from electrolysis – if used wisely and efficiently – can be that path to a sustainable future,” Howarth said. “Blue hydrogen is totally different.”

The ominous paper comes just days after the US Senate passed its $1 trillion Infrastructure Investment and Jobs Act, with $8 billion of that earmarked for hydrogen energy development. At the same time, governments in the UK, Canada, the EU, China, and many more are ramping up their commitment to hydrogen as a clean fuel source. That makes it all the more important that people understand the consequences of using blue hydrogen, Howarth says – and that they don’t accept the industry’s tenuous claims of the fuel’s low- or zero-emissions status.


“Political forces may not have caught up with the science yet ... Even progressive politicians may not understand what they’re voting [for],” he warned.

“Blue hydrogen sounds good, sounds modern and sounds like a path to our energy future. It is not.”

 This Week in IFLScience

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  • climate change,

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