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Discussion Starter #1
Many specifics on hydrogen are frustratingly opaque, so I thought this discovery was worth sharing. It's a document from the NREL showing statistics for all the American H2 filling stations, compiled November 2017.

https://www.nrel.gov/docs/fy18osti/70527.pdf

The highlights are on page 25.
Some interesting points:
  • Producing hydrogen via electrolysis uses an average 62 kWh per kilogram. This means that the Honda Clarity Fuel Cell uses 3.13 times as much electricity as the BEV version, before even looking at other electricity uses such as compression and cooling in the storage tank.
  • Compressor averages 1.67 kWh electricity used per kilogram of hydrogen, which is better than I'd seen elsewhere.
  • Average filling rate is 0.83 kilograms per minute, so it would take an average 6 and a half minutes to completely fill a Clarity tank from empty (5.46 kg, 366 miles). Obviously that's still very fast compared with any BEV on the market today (by my calculation it's equivalent to just under 1MW charging), but surprisingly it's several times longer than filling a petrol/diesel.
  • There's some data on the maintenance that goes into the stations, although I think this is muddied by comparing on-site electrolysis retailers with delivery retailers (and even then, some deliveries use liquefaction and others compression). It amounts to 91 hours' maintenance per station per quarter, or $10,578 per station per quarter.
  • Safety reports are logged. No actual incidents happened, but there are several "near misses" - a hydrogen release sufficient to sustain a flame if ignited. On average there was an H2 leak for every 505 fills.
  • Last point is something that's a bit mystifying to me, would appreciate if someone could clarify. There's a log of electricity costs at delivery retailers (as opposed to on-site electrolysis), both in terms of $ per kWh of electricity and $ per kilogram of hydrogen supplied. For compressed delivery, it's an average $0.35/kWh, and $8.36/kg, so does that mean these stations use 23.89 kWh per kilogram of hydrogen even when it's generated off-site??
There's also a bunch of data on average filling pressure, I'm not sure if you can draw any conclusions from it. Statistics I've been wanting for ages are how much pressure is lost during a fill, how long it takes to repressurise the filling system, and whether the car can actually be filled during the interim.
 

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Last point is something that's a bit mystifying to me, would appreciate if someone could clarify. There's a log of electricity costs at delivery retailers (as opposed to on-site electrolysis), both in terms of $ per kWh of electricity and $ per kilogram of hydrogen supplied. For compressed delivery, it's an average $0.35/kWh, and $8.36/kg, so does that mean these stations use 23.89 kWh per kilogram of hydrogen even when it's generated off-site??
Part of it may be that there's refrigeration involved as well as compression ("chiller" mentioned in some slides), which may not be in the 'compressor' 1.67 kWh/kg.

Also, those electricity costs are over a huge range, some of them very expensive, so I suspect there's demand charges and similar included; depending how they have done the averaging, that may render your calculation invalid: quite likely the lower users are paying the higher prices per kWh (using the same gear, so same demand charges for when it's turned on, but less kWh total to spread it over). It's a shame they obfuscate it by turning everything into dollars rather than just showing the kWh used.
 

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Discussion Starter #3
The figures I've previously found for cooling are even lower than compression, so that's probably not it. I agree that there's likely some weird complication with how the costs are compiled.
 
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