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Comment by hatthew | Hacker News Reader

> Fuel cell buses do produce sufficient waste heat, but here’s the problem: it’s exceptionally expensive heat. Every degree of warmth comes from hydrogen — a fuel that’s costly to produce, store, and transport. Unlike diesel, heating with hydrogen’s waste heat is technically easy but economically painful.

Isn't waste heat pretty much free by definition?

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Within one technology, that'd be true. But not if you have the option to choose another technology that produces a lot less waste heat.

Yeah, I just find the framing very weird. It's talked about as if it's somehow worse than diesel. But then isn't the issue that hydrogen fuel is less economical than diesel in general, regardless of whether the fuel is used for locomotion or for passenger heating? In the context of passenger heating specifically, waste heat is either free for both diesel and hydrogen, or equally non-free for both.

Also the article appears to be arguing for electric instead of hydrogen buses, but for some reason seems to try to frame "winter range" as being an issue for hydrogen buses specifically, and then says "electric buses face a different challenge" -- winter range.

I feel like there are two separate points that can be made:

- Hydrogen fuel is more costly than diesel or electric (not even sure how true this is, but it's what the article seems to indirectly imply).

- Hydrogen fuel doesn't have winter range issues the way electric buses do, but regardless electric is still better for other reasons.

Hydrogen fuel (gray) is often about $8-10/kg, which is about an 80% increase in costs per mile over diesel. Green hydrogen is like $14/kg.

Additionally, agencies are experiencing vapor losses of fuel, which results in an overall increase in fuel costs. These losses can occur in different circumstances, but often occur after fueling when the gaseous fuel left in the hose (that cannot be returned to the liquid tank) evaporates. One agency reported double the cost of fuel due to these losses.

Anyway, yeah I think the argument in the article was that this waste heat isn't "free" because you're paying such a premium for it via the fuel costs.

Yes it is. You've accounted the price of the heat in efficiency/fuel cost already, the heating is free, and not "exceptionally expensive heat".

I wish there were a common framework for this lose and hand-wavy accounting. For some people this is painfully wrong, while the rest are not even convincible about it.

Anyway winter or cold temperature is an advantage for hydrogen in hydrogen vs electric, precisely because heating is free. They get the reasoning wrong. I think "exceptionally expensive heat" is just made up to illustrate their point. Trash "article" either way.

Thanks, you beat me to it. While it is more expensive per watt, that's a sunk cost: you've already paid it when you were consuming the hydrogen to make the bus move.

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