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Comment by b112 | Hacker News Reader

Not any more than electricity.

With electricity, each thing we convert from petrochemicals to electricity, prevents us from offlining the first power source we'd otherwise decommission.

And the first thing we'd decommission would be the dirtiest power plants, eg Ng, coal, or some such.

H2 can be made clean, and so can electricity. No difference.

What we need to do is scale up clean h2, and support it. More clean tech is better, it's not a competition.

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H2 has higher losses in converting energy into hydrogen and hydrogen back in to energy though. And currently like 99% of hydrogen is obtained via fossil fuels, not split from water. Hydrogen could at some point be the equivalent of electricity and batteries, but currently it isn't any different than using straight fossil fuels.

Its a lot cleaner than directly burning fossil fuels, and carbon capture is possible. If the fossil fuel is methane then by product is solid carbon, not CO2.

Also, if we have hydrogen supply chains we can use them to hand hydrogen from different sources in the future.

The technology is not here yet, but it is being developed. Battery EVs were completely impractical not long ago.

I think they still are.

Third world countries can't make sweaters without violating 100 EPA and civil rights regulations. But they mine lithium cleanly? I don't believe it.

The problem with h2 compared to electricity is that it has abysmal round trip efficiency. It makes sense for a few, limited use cases and an excavator may be one of them - if they’re used in places where no electric grid is available. In almost all other use cases, batteries provide a better efficiency.

The biggest problem with electricity is the batteries. Right now an EV pollutes more an ICE engine, the pollution is just moved to the power plants. But then you have to take into account the batteries. Making them pollutes a lot and they don't last forever.

We should be minimizing the use of cars instead.

Commuter EVs are the rare kind of electric consumers that can efficiently absorb the unstable solar-generated electricity. Having your car charged while you're in the office during daytime can effectively be free in many places.

Fully agree on minimizing the use of cars. But I still wanted to do this computation to compare:

EPA says a gallon produces 8.8 kg CO2/gal tailpipe emissions [0]. A best-case sedan does about 50 mi/gal [1]. That's 17.6 kg CO2/100 mi for a best case sedan.

A Tesla Model 3 uses about 25 kWh/100 mi [2]. 1 kWh produces about 1 kg CO2 when produced in the dirtiest way (coal), but in the US it's currently about 0.4 kg CO2/kWh on average [4]. That gives you 10-25 kg CO2/100 mi.

So the best case ICE is better only if you are producing the electricity from coal (even gas power is better than ICE). The nice thing about EVs is that you can often charge them with the cleanest power (e.g. solar), but I'm not sure how common that optimization is.

[0]: https://www.epa.gov/greenvehicles/greenhouse-gas-emissions-t... [1]: https://www.fueleconomy.gov/feg/findacar.shtml [2]: https://www.fueleconomy.gov/feg/Find.do?action=sbs&id=46206 [3]: https://www.eia.gov/tools/faqs/faq.php?id=74&t=11 [4]: https://app.electricitymaps.com/zone/US/12mo/monthly

CO2 emissions from the gasoline does not account for the energy necessary to refine the oil to produce it. These days refineries use electricity for that so if that comes from a coal plant, it adds like 25% of CO2 emission. So the best sedan is pretty much equivalent in the carbon emission to Tesla when that car uses electricity from an old coal plant with 30% efficiency.

A statement like "EVs pollute more than ICE engines" needs substantiation.

Large power generation systems (even messy ones like coal) are tremendously more efficient per unit CO2 produced than a car engine[1]. You could make a case, though it's been proven wrong many times, that the production of the battery in an EV generates more waste than a comparable ICE vehicle.

https://www.cotes.com/blog/greenhouse-gas-emissions-from-ev-...

And electric motors are way more efficient than ICE motors that hardly reach 40% efficiency.

This is a common myth. Most of the pollution of a vehicle is in its use, both for EVs and ICE [0]. The average EV, even on the dirtiest fuel, still has much higher efficiency than the average ICE. On top of that, things are only going to get better:

- more of our electricity is coming from clean (renewable/nuclear) sources every year. We reached 40% in 2023. [1] Solar and wind are dominating fossil fuel in new generation. [2]

- we're evolving battery materials for cleaner batteries, and more new battery materials will be sourced from recycled batteries instead of new mining. (EVs are still so relatively new and batteries live long enough that we haven't yet reached that point).

0) https://www.epa.gov/greenvehicles/electric-vehicle-myths#Myt... 1) https://www.wri.org/insights/clean-energy-progress-united-st... 2) https://www.eia.gov/tools/faqs/faq.php?id=427&t=3

H2 could solve intermittence, on-vehicle batteries can't. Not if the charging has to be squeezed into a tight work schedule.

The biggest challenge, besides the obvious one of just building a huge quantity of wind and sun harvesting installations, is hydrolysers that make sense technically and economically when they operate far from 24/7, as the inverse of peaker plants.

H2 is a terrible substance; it destroys whatever you use to store it, it leaks like crazy, you need to compress and chill it to get any kind of density, you need to store it at crazy low temperatures.

For instance, the toyota Mirai's tank has a finite lifetime of 15 years from when it was made before it has to be replaced.

A good setup might be a nuke plant with a couple huge batteries along side, mixed with some grid PV and wind, and per-home battery, smart hot water heaters, and local PV.

H2 is just a silly fuel and a silly battery. Except on rockets where it's still silly but not quite as silly.

That's why you'd usually want to only use the H2 as an intermediate step on the way to some other e-fuel. Which can be as simple as iron powder to be oxidized at the application site. But the first step, in all e-fuel processes, is always the hydrolyser. Coupled with with local H2 storage so that at least the downstream processes can operate closer to 24/7 than the hydrolyser. Batteries don't scale to seasonal, fuels created downstream of a hydrolyser do. The trick is to build the hydrolysers (and downstream processors) at sites where that H2 buffer is easily created. Salt caverns are the usual candidate.

(yes, this is a little off topic under an article about an H2 excavator. But if they solve all those problems, I'll applaude them, because at one point we'll either have green H2 available or we'll cease to be an industrial society, of they don't, well it's their problem they tried, not mine)

>Not any more than electricity

>H2 can be made clean, and so can electricity. No difference.

Which electricity is clean? If you have clean electricity then you don't need hydrogen.

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