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“Battery EV” vs “Hydrogen Fuel cell EV”

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coppice:

--- Quote from: Miyuki on March 30, 2022, 07:21:04 pm ---
--- Quote from: tom66 on March 29, 2022, 10:32:38 pm ---
--- Quote from: emece67 on March 29, 2022, 10:25:58 pm ---I wonder if, someday, I could trickle H2 into my car, H2 that I produced locally from my PV panels (or wind generator, or...).

--- End quote ---

H2 cars are 35MPa or 70MPa fuelled, so require equipment about the size of a car to just pressurise that.  Rather difficult to imagine that happening at home.

One method would be to charge up the small battery that most H2 cars have, if you didn't expect to produce much energy.  I seem to recall the Toyota Mirai has a 2kWh Li-Ion battery on board which is used to buffer the output from the fuel cell.  Fuel cells tend to be rather lethargic in ramping up production so the battery fills in the demand, and of course offers regen braking too.

...but then that's basically just a plug in hydrogen EV, which is a weird concept.

--- End quote ---
35MPa is not a huge issue
Look at Scuba tanks, they are commonly pressured to 30MPa with a small portable unit
I know it works with air so it is a safer medium
But technically it is not an issue at all

--- End quote ---
Have you seen the tanks in the Mirai and Nexo? They operate at 70MPa, rather than 35, but they are huge tanks with a small capacity. Hydrogen is much harder to deal with than air for scuba tanks. Those tiny hydrogen molecules leak through things that seal up tightly for air. The safety requirements are on a different scale, too. If an air tank blows up its dangerous, but leaks are mostly harmless. Anything that isn't just right with hydrogen is dangerous.

tom66:

--- Quote from: Miyuki on March 30, 2022, 07:21:04 pm ---35MPa is not a huge issue
Look at Scuba tanks, they are commonly pressured to 30MPa with a small portable unit
I know it works with air so it is a safer medium
But technically it is not an issue at all

--- End quote ---

Hydrogen is cryogenic at 35/70MPa.  That's nothing like air.

Have you seen the equipment at hydrogen stations?   The equipment is enormous - and expensive. Could it be reduced in size?  Almost certainly, but it is still not a trivial piece of equipment.  Not to mention the power consumption.  This source suggests a power consumption of 140-300kW for a compressor motor.  https://www.nrel.gov/docs/fy14osti/58564.pdf  (pg 24)  Perhaps you could reduce that by reducing the hydrogen production rate, but it is still likely to be substantial.

nctnico:

--- Quote from: tom66 on March 30, 2022, 07:49:56 pm ---
--- Quote from: Miyuki on March 30, 2022, 07:21:04 pm ---35MPa is not a huge issue
Look at Scuba tanks, they are commonly pressured to 30MPa with a small portable unit
I know it works with air so it is a safer medium
But technically it is not an issue at all

--- End quote ---

Hydrogen is cryogenic at 35/70MPa.  That's nothing like air.

Have you seen the equipment at hydrogen stations?   The equipment is enormous - and expensive. Could it be reduced in size?  Almost certainly, but it is still not a trivial piece of equipment.  Not to mention the power consumption.  This source suggests a power consumption of 140-300kW for a compressor motor.  https://www.nrel.gov/docs/fy14osti/58564.pdf  (pg 24)  Perhaps you could reduce that by reducing the hydrogen production rate, but it is still likely to be substantial.

--- End quote ---
But these installations are setup for large amounts of hydrogen. You can buy >2MW air compressors as well. It just depends on how much volume you need to compress in which amount of time. The report also lists costs per kg of hydrogen. Those are much more interesting but are likely outdated due to the age of the report. The high number is US $1.5 per kg which translates to about US $0.02 per km assuming travelling a conservative 80km (*) per kg of hydrogen.

* Toyota claims their hydrogen fuel cell vehicles travel 100km on 1kg of hydrogen. WLTP results for Mirai show 0.79kg per 100km.

rstofer:
I view the fuel cell as the same as LPG (propane):  Fine for fleet use from a central service yard, not very practical elsewhere.  City buses, maybe taxis (if Uber doesn't wipe them out), other governmental vehicles - these will all work fine on a fuel cell.  I don't see the day when there will be fuel cell charging stations on street corners.

Even our grocery store has installed about a dozen charging stations.  I haven't been to the store since COVID started but one day I'll look into it.

With an 8 kW solar array, I was driving my Spark EV for $0.05/mile.

Marco:
If no other solution is found, I could see cryogenic hydrogen replace cryogenic LNG for long distance trucking.

Cryogenic LNG is a proven system, the increased losses and cooling requirements for hydrogen will make it more expensive, but it's still all in the same ballpark. If push comes to shove and fossil is plain banned the options are limited.

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