Hydrogen isn’t “clean” in any sense and I dislike that adjective is used so commonly with hydrogen.

When burned in air it produces far more NOx than burning methane due to higher temperatures. For example, one popular idea (hydrogen blending - HENG) is to mix it into the natural gas people burn in their homes. But burning a 15% hydrogen blend leads to a ten fold increases in health damaging NOx over burning natural gas.

And leakage during transportation is much worse than NG - particularly in liquid form. Combined with fact that leaked hydrogen is an extremely potent (indirect) greenhouse gas with more and more studies arriving at a number between 10 and 13 for its GWP100 (https://cicero.oslo.no/en/hydrogen-leaks-add-to-global-warmi... for example).

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rhubarbtree 10 hours ago | parent [-]

Hydrogen isn’t burned in fuel cells, though? So hydrogen used in fuel cell, such as hydrogen powered vehicles, is indeed clean.

	▲	derriz 10 hours ago \| parent [-]
		Sure - but I wasn’t claiming that consuming it always produced huge amounts of NOx - I was pointing out that having hydrogen involved doesn’t make a process “clean”. And burning hydrogen in air is being pushed/proposed - not just domestically in the form of hydrogen enriched NG but also for grid scale electricity generation in gas turbines.