Hacker News Reader

Comment by Incipient | Hacker News Reader

With the amount of lithium required in batteries for ships, and the issues with recycling them, is green hydrogen/synthetic fuel not a better option overall? Or are these options too expensive?

View on HN

Green hydrogen has terrible economics. With green hydrogen you take $1 of electricity to get $.50 of hydrogen bond energy and then run it through a fuel cell to get $.25 of propulsion. It is worse when you account for compressing the hydrogen, and much worse if you burn or convert the hydrogen to liquid fuel. With batteries, you take $1 of electricity and get $.90 of propulsion. Hydrogen is not realistic.

Not really, electricity prices only need to fluctuate by a factor of four for this to be economically viable.

I agree, it only make sense if you have so much excess solar that you don’t know what to do with it in peak production. Even then, you need to factor in the depreciation of the hydrogen facilities.

But is it completely green? I live fairly close to a huge lithium deposit, and while people from western world are enjoying the benefits of EVs, people around here might get their habitat destroyed.

In my book it’s not green if it’s not completely green. And EVs are certainly not.

Yeah, shipping does seem to be one of the main applications where green hydrogen actually makes sense. Battery chemistry should improve to the point where basically no road transport should need anything else over the next 20 years (we're basically already there for most car applications, still some improvement needed for trucking etc., although maybe battery swaps is a better model there anyway). Ships need huge amounts of energy, but have the space to deal with hydrogen's poor volumetric density, unlike aviation, where I think synthetic fuel is a better option.

Agreed. Why not liquid natural gas?

https://www.freightwaves.com/news/largest-lng-powered-contai...

https://afdc.energy.gov/fuels/natural_gas_renewable.html

Ammonia or methane would be a better choice. Hydrogen is a bit awkward for mobile applications, at least while metal hydrides are expensive and made of scarce materials.

Maybe we need smaller hydrofoil container ships

Well Boundary Layer Technologies (a Y Combinator portfolio company) is working on that. But it will never be more than a small niche market for high-value, time-sensitive cargoes.

https://www.boundarylayer.tech/

> small niche market for high-value, time-sensitive cargoes.

You mean air freight, right?

They're aiming for the niche market that's slower than air freight but faster than displacement hull cargo ships. Not sure if that market is really large enough for a viable business, but we'll see.

Reply on news.ycombinator.com