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Comment by kylebenzle | Hacker News Reader

The idea endures because produce fuel from nothing but water and sun light and left with no emissions is incredibly promising.

I would ask why nearly everyone has contentedly continued using rare earth mineral, cobalt and fossil fuel to power out vehicles when a clean renewalabl source is right here.

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Hydrogen is not a source of energy, it is a carrier. You have to create hydrogen gas from water (or as is done today, from fossil gas). This takes energy. This energy can just as well be used to power the thing directly. Which is significantly more efficient.

https://pbs.twimg.com/media/D0MuwO9V4AEGbUo.jpg

Hydrogen is brought up as a potential storage method which may work, but it makes metals it touches brittle. It is not like storing fossil gas. There are ways to limit it, but it has costs.

https://en.wikipedia.org/wiki/Hydrogen_embrittlement

Hydrogen in cars also uses expensive metals, platinum in the fuel cell.

https://www.sciencedirect.com/science/article/abs/pii/S03603...

Because "rare earth minerals" aren't that rare, are pretty easy to recycle (making them renewable), and batteries have end to end efficiency of ~80% compared to ~20% for hydrogen.

Also, Li-ion batteries don't really use rare earth metals (there's a little yttrium in some varieties of LFP cells). The idea that REs are needed for batteries dates back to nickel metal hydride batteries, which Li-ion batteries supplanted.

> easy to recycle

Maybe. But IIRC practical reality is that no one actually does this, and there is no infrastructure setup for this. Something like <1% of rare earths in product are recycled.

Please correct me if I'm outdated.

They’re currently so cheap and plentiful that it doesn’t really make economic sense to recycle them. They’re recyclable in the sense that it would become a realistic option if supplies became limited, which isn’t true of everything.

EVs (and their resulting large battery packs) haven't been available at scale long enough, but there are already established businesses for recycling standard car batteries and it's why you pay a separate "core" deposit in the US to ensure they go back into the system.

People are starting these businesses already, it's yet another logistics problem to solve. Right now there is more money in pulling apart the packs the using the cells as salvage than there is recycling, but as more and more EVs reach end of life you can bet it will be a sizable market.

Everyone compares Li-ion recycling to starter battery recycling, but starter battery recycling is extracting a single element that makes up almost all of the mass of the battery. There are many different cathode chemistries all in use for lithium ion cells, so the logistics problem is significantly more complicated.

Presumably a specific chemistry will end up winning out for chars, but, IMO, most of the cars on the road now will never have their cells recycled.

basically all batteries now are 1 of 2 types, and the differences within those types largely relate to manufacturing methods and trace elements that probably aren't worth recycling anyway.

Pretty sure this is what Redwood does: https://www.redwoodmaterials.com/

The difficulty with getting LPG fueled vehicles off the ground should have demonstrated the foolishness of pursuing a fuel even more difficult to handle and with no large scale delivery mechanism already in place.

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