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Comment by ZeroGravitas | Hacker News Reader

I wonder how much more efficient/cheaper in theory these need to be than the standard PV -> electrolyser route before they make sense.

Seems like the ability to have interchangeble electricity (which you can export and import to the system as needed) and the ability to locate the hydrogen production an aribtrary distance (with a transmission loss) from the energy gathering stage seem like a very decisive advantages, even before you consider the immense amounts of time and focus that are being put into improving PV cost and efficiency.

If this method works well, you'd probably still need to consider whether it would make more sense to generate the light artificially for similar reasons.

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A potential use for this would be to use the hydrogen as a way to cheaply store the energy to be used when the sun is not shining. I.e. Pair it with fuel cell tech to generate electricity at night.

In this scenario the price of the tech should be compared to solar + batteries per kWh, and I could imagine that at scale hydrogen storage could beat out the cost of betteries.

Energy density is another big factor. Hydrogen has a much higher energy density especially for automobile use compared to batteries.

My opinion, fwiw, is that batteries have won the day in the automobile space. The infrastructure investment required to make hydrogen work for automobiles must be astronomical vs incremental improvements required to the existing electrical network.

Couple this with the fact hydrogen distribution and storage have some significant problems, plus recharging at home/work/parking is super convenient.

The only real thing stopping battery powered electric cars from being the obvious first choice in many markets is the cost of battery packs. Conveniently this has progressively improved yer-on-year. It is simply a matter of time.

I’d imagine quite a lot. The fungibility and cheap, instant long range transmission of electricity is worth an awful lot of ungainly hydrogen in a tank somewhere else that you can’t use.

It's more of a cost than an efficiency equation. The efficiency only matters in the sense that it drives up the cost because you'd need more equipment to produce hydrogen. The equipment is fixed cost investment. So, the longer it runs, the more fuel it will produce.

Using stored energy to produce light to produce energy does not make a whole lot of sense. It's a very lossy process. If you have stored energy, maybe just use it directly?

The article mentions a 5% solar efficiency, it is my understanding that the current most efficient PV panels are around 22% solar efficient. So I would think You may be correct.

It would be nice if they compared PV panel powered electrolysis hydrogen generation against this new tech.

For many applications, efficiency is not that important. The important metric would instead be $/kwh.

I agree, but isn't that a sad state of affairs?

The Libretarian in me wants to believe that eventually the Efficiency and $/W will balance out but at what real cost?

$/W might make sense from 40,000 feet but the grounded pragmatist in me feels there are other things to consider and confirms this by the ironic inevitably of one of those other things ending up crushing the $/$ formula, and here we are now.......

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