9
votes
Hydrogen cars have gotten a lot of hate lately, and only some of that is deserved
Link information
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- Title
- You're Wrong About Hydrogen Cars
- Authors
- Linus Tech Tips
- Duration
- 14:15
- Published
- Jan 11 2022
I saw this yesterday. In my opinion the author has drunk just a little bit too much of of that Toyota Tea. I do think that he's right that it's a way better option for trucking, where you do need the ability to refuel quickly and travel long distances, but it doesn't really make sense for consumer cars. Hydrogen is expensive, inefficient compared to batteries, and more importantly there's practically zero infrastructure for Hydrogen across the country (though that last bit can and ideally will change, at least for commercial trucking).
I do like the idea of using hydrogen generation via electrolysis as a potential solution for the overproduction of electricity from renewable sources during off hours, but I wonder how good an idea it is really; even if there is more power to be made there are real costs for it to be generated; turbines and solar cells will all eventually wear out after all. And I wonder if there aren't other industries who would be willing to buy up those extra kilowatts who can stand the mixed availability.
From what I've read, it's ridiculously inefficient, to the degree that it's used almost nowhere industrially, as it's so much cheaper and easier to harvest it as part of the petroleum refining process. I kind of have doubts about how viable it would be costwise because of that.
You can also use it to generate synthetic methane as a fuel reserve for when things get dark and calm. In that case, you'll need so little of it (only once all the batteries are dry) that the efficiency of the process is going to be a non-factor compared to the infrastructure cost of such a system. Going for synthetic methane also simplifies the infrastructure part, as you'll just use the natural gas pipes we already have.
Another problem is hydrogen is being pushed by existing fossil fuel companies as a solution, instead of sourcing hydrogen from a non-fossil fuel source.
There's actually a really big drop in efficiency to use hydrogen instead of batteries, and the video has a whole segment about it. From electricity generation to your car's battery and back again is 70-90% efficient, vs from power to hydrogen, compression, filling, and going back to electricity again you're looking at 25-35% efficiency. There's dramatically more infrastructure needed to switch all of the US to hydrogen than there would be to switch to batteries.
I really love hydrogen fuel cell technology - it's literally the only 'new' tech that's come out in the past 20 that actually feels like the magic. The only real problem is that implementing it has a lot of real-world complexity, so it's not the panacea that Toyota pretends it is. That's why I find it so much more compelling for commercial trucking rather than personal vehicles.
This discounts the efficiency with which the electricity was made, transmission and storage. If you’re going full renewable generation than maybe we don’t care, but if it’s some large scale top-of-the line power plant, that might be 60%. So you’re looking at 70-90% of 60%, or roughly 40-55% net efficiency. Add in some more (smaller) transmission losses, or any losses due to energy storage (optional, but highly recommended for renewable) and it doesn’t seem so wildly different anymore
Both of those figures I quoted included transmission and storage losses and did not include the efficiency with which the electricity was first generated (which is irrelevant in this conversation).
Did neither of you watch the video? For the record here is everything wrapped into one diagram, and here is the start of the segment where he talks about energy efficiency.
Now that I have re-read my comment, I realize I may not have been accurate enough; that 70-90 figure also includes the loss of efficiency from storing it in the battery. I'll correct it now.
I'll point out that the source of that diagram is a Volkswagen press release. Last year Volkswagen vocally came out against hydrogen fuel cells in favor of the battery-based vehicles it is currently developing.
I should have been clearer (but it was late, and I was on my phone :P) -- my point is more that you can't decouple the generation efficiency, particularly for renewable electricity generation specifically because without redesign of the grid, you need energy storage solutions in order for renewables to actually meet power demand when the source is not generating.
So either: you have a fossil-fuel based generation mechanism, which can give some efficiency at cost of CO2 emission, but reliably produce power, or you need to have (something) like "pump water up a hill", "use LHTES to store solar thermal energy", "ludicrously large batteries", etc., etc.
Whereas, the generation of hydrogen itself is the energy storage mechanism. Granted, if the hydrogen generation is say 1% efficient, maybe it would be better net efficiency to go with renewables + an energy storage mechanism. But, as we've seen with Solar -- the efficiency, cost, and accessibility of a technology can wildly improve as it starts to catch on.
/u/dubteedub said it well, I think
The reason why I was trying to decouple the generational efficiency was to make sure that we were comparing apples to apples; the efficiency problem exists for both the present, where we are dependant on combustion fuels for the majority of our energy, or if we are in a future utopian 100% renewable energy power grid.
Your argument does make more sense when you talk about power availability; that's a topic I'm already well aware of. The one thing you are forgetting is that BEVs already have batteries - in other words, they are already storing the energy for when it's needed most! Most BEV and even plug-in hybrid owners take advantage of that fact by charging their car's battery when the cost is lower. That being said, a more centralized control of when the energy is to be stored and released is probably a more ideal solution in the long run.
But I think that both you and @dubteedub might have misunderstood what I meant by my original comment; when I was talking about hydrogen being a bad idea, I was talking about it being a bad idea in the context of today. I've got essentially the same takeaway as the video - There's just too many negative aspects to buying one vs. a BEV.
In the "technology is ready for deployment" state, efficiency really does matter even for renewables.
If you have a fixed energy budget, for a less net efficient generation process, you have to build more renewables (which then requires more extraction, manufacturing, etc., and all the fun that comes with that) just to meet the demand.
Alternatively, you must reduce energy use, which ... is hard, but should be pursued regardless.
I totally agree though that the beginning of a technology is not the time to quibble about where the efficiency is though. If we had, Solar would still be < 1% efficient.