Electrochemical cells (especially PEM electrolyzers) are notorious for containing materials far more expensive than copper (noble metals). But they pay for themselves much more quickly than you might think, if you can get offtakers to actually purchase and use the resulting products.

The biggest challenge facing these climate tech industries right now is the chicken-and-egg problem. You can't make anything cheaper than the centuries-old fossil-based competition unless you do it at scale; you can't scale it without offtakers; offtakers won't participate unless it is cheaper than the status quo.

There are compounding issues with expensive infrastructure upgrades (e.g. airplane or maritime engines that need to be upgraded to handle new fuels; pipelines or fuel trucks that need to be build to handle hydrogen, etc) that further push out the break even date. And then you have oil & gas companies inserting themselves into these efforts in order to greenwash their businesses, causing many would-be supporters to oppose entire clean technologies due to the perception that green tech startups are in bed with the fossil industry.