101–110 of 126 posts
Somewhat off-topic: why "2k kilometers" instead of 2 megameters? I do realize that in daily life people rarely use distances of that order of magnitude, but the semantic connections between kilobits megabits, kilowatts megawatts appears to be entirely accessible to essentially all adults, so why use the awkward "thousands of kilometers" instead?
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Why do fertilizer and steel require hydrogen in particular rather than just green-electricity-powered induction heating? Is the hydrogen meant to be a chemical component in the manufacture of fertilizer and steel rather than merely a heat fuel?
Hydrogen is needed for the Haber-Bosch process for making ammonia. For steel making, hydrogen would be used for reduction of iron ores to iron metal (currently, most of that is done with coke). There's also a large market for using hydrogen to upgrade petroleum (hydrodesulfurization), but that market continuing to exist presumes some way of dealing with the CO2. Direct air capture, perhaps. There could also be market…
Wouldn't electric reduction cells like those used in aluminium production work as well? Why would you need an input of hydrogen?
I've read Company X develops Hydrogen car for decades now. Not an expert on feasibility, but I doubt any of these cos. have the guts to start a new category like this, and will wait for somebody else to prove value first. This is how Tesla prospered in the first place.
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To add, LPG stations are pretty much everywhere in both Canada and the UK as well.
I found it interesting how Canada uses LPG even though the winters get cold enough that LPG isn't usable. I lived in Alberta for a year and they had a warning that when it got below -40 the buses would not run. School was not cancelled when this happened, you had to find an alternate way to get there. They did helpfully remind you that exposed skin would freeze in about 5 minutes.
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What about using hydrogen as a generator for an EV like in the Hyundai 74 concept? I’m far from an expert but something like that, at least intuitively, feels like a nice compromise with having portability of fuel, but still allowing for alternative power sources via electricity (like if grid power was sourced via solar, hydro, wind, etc).
I don't understand what problems the Hyundai 74 is trying to solve. It has roughly the same stats as a long range model 3 for acceleration and range, but has to carry around both a fuel cell and a 60+ kwh battery (nearly as large as the model 3's). Hydrogen mpge is already terrible (all hydrogen mirai has 75 compared to long range model 3 at 130), and an extra step here is only going to make it worse. Is there someth…
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Batteries needed electric vehicles are still expensive and seem to essentially be the bottleneck for mass change to EV. The infrastructure needed to support battery electric vehicles seem to be expensive/complex to run sufficiently well in practice. In the US Tesla's supercharger network is often cited as a moat against other manufacturers. It's not even building the chargers - it's maintenance and compatibility. Cha…
The Tesla network in Europe is compatible with everything else. All vendors are using CCS2. I know it's different in the US, but even there it seems to be changing. The main advantage Tesla currently has is the size of the network as well as the seamless integration into their navigation system and automatic payment without a custom card. However this could be easily done by competitors if they would grasp the import…
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Hydrogen is needed for the Haber-Bosch process for making ammonia. For steel making, hydrogen would be used for reduction of iron ores to iron metal (currently, most of that is done with coke). There's also a large market for using hydrogen to upgrade petroleum (hydrodesulfurization), but that market continuing to exist presumes some way of dealing with the CO2. Direct air capture, perhaps. There could also be market…
> hydrogen would be used for reduction of iron ores to iron metal Wouldn't electric reduction cells like those used in aluminium production work as well? Why would you need an input of hydrogen?
There are a few engineering difficulties arising from the high temperatures required and the chemicals around.
And note that aluminum smelting also releases quite a lot of carbon dioxide for various reasons, one of them being consumption of the graphite electrodes.
1. https://en.wikipedia.org/wiki/Electrolytic_iron
2. https://www.newscientist.com/article/dn9878-electrolysis-may... (2006)
3. https://link.springer.com/article/10.1007/s10800-017-1143-5 (2018)
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Fertilizer requires the production of ammonia NH4. That is one nitrogen bonded to 4 hydrogens. The nitrogen can come from the air but the hydrogen has to come from some other compound.
Dumb question: why can't the hydrogen also come from the water vapor in the air?
Currently nearly all ammonia is produced by "steam reformation" of methane in air (which is mainly nitrogen). Very hot steam, air, and methane are mixed. The carbon in the methane is released as carbon dioxide.
The idea is to take the methane out of the process.
Hydrogen is very appealing, but the lack of a distribution system makes it highly unlikely. It's hard to see Toyota and Honda continuing to make hydrogen cars much longer. Maybe for trucks?
If you consider the whole chain of energy conversions, hydrogen has a very poor efficiency:
- electrolysis to split water; or super heated steam to split methane. 30%-40%: at best.
- compressing it for transport at typically 300bar: not sure; but it isn't free (theromdynamics). And also, some of the hydrogen is likely to slip away. Let's be generous and call it 80%
- transporting it by truck or via pipes takes more energy. Also hydrogen trucks have a pretty pathetic energy density compared to e.g. a truck load of diesel. You need a lot of trucks. Which need fuel (and let's assume that is hydrogen) At about 18:1 ratio. And some more of it slips away. So, let's be generous again and call that 95% efficient.
- fueling the car/truck uses compressors, pumps and cooling (expanding gases produce heat). This too is not free.
- finally you have the choice of using it in a fuel cell at 70-80% efficiency or burning it in a combustion engine; which is more like 40% efficiency.
If you multiply all of that you end up with the reason why using hydrogen for transport is an absolute last resort because of all the energy losses that you still have to pay for.
25% efficient would be pretty good. It's probably much worse than that. Some of it might be fixable but the laws of thermodynamics just aren't very flexible. There is no magical solution to many of these inefficiencies.
So 4x the fuel cost, or drive an electrical truck. Easy choice for a lot of companies. Especially if they can generate their own cheap power.