Did you consider the Honda Clarity before your Prius Prime?

Yes, very, if it had a silent electricity generator that could generate 100+kWh of electricity (which could come from as little as 6kg of H2 - at 1000Wh/kg).

 

All that complexity and cost to end up with throughput efficiency of 20-25%

Thanks, but I'll pass.

 

You end up about break even energy-wise with a BEV because the BEV has to haul that heavy battery around 100% of the time when you only need it a few percent of the time.

And fuel cells are like a thousand times less complex than an ICE, with about the same energy density, both of which are like 5 times better than current day batteries.

 

As you've found with your Prime and I'd already experienced with our BMW i3-REx and Prime, 6-18 kWh battery capacity works great for ordinary urban driving. The BMW i3-REx has shown the ICE or fuel-cell equivalent doesn't have to be that large. But my problem remains with high pressure, hydrogen gas.

Generate the hydrogen on the fly from a liquid or solid carrier and my objections vanish. The chemistry is well known:

• hydrides - these can store a lot of hydrogen and release it at modest rates. They don't charge fast but there is no reason why a standard hydride could be 'exchanged' at a filling station where re-hydrogen generation is not time limited.
• alcohols - there are several promising technologies and they look to be carbon neutral.
• anhydrous ammonia - my favorite.

It is compressed, 10,000 psi, hydrogen that just doesn't make sense.

Bob Wilson

 

What's wrong with high pressure gas?

Hydrides are thermally inefficient and mass inefficient. That's why Nickel Metal Hydride batteries (technically nickel hydrogen batteries with hydride storage for the hydrogen) are so mediocre.
Direct ethanol or methanol fuel cells are promising, but currently have very low power density.
Ammonia is highly toxic.

 

A high pressure leak becomes an invisible knife. The fueling is mechanically complex due to high strength, accurate machined connectors that are needed and will wear out. The need for large , high pressure tanks, another problem that has a built-in age limit due to the cycling mechanical strain.

Just it is so safe compared to the alternatives.

I spent a summer working in an ammonia cooled, ice plant. I've smelled a lot and the foul odor is a safety feature. Exposed to the atmosphere, it quickly dissipates and a water mist sucks it into solution. Compared to a gasoline spill, liquid ammonia soon 'cleans itself up.' Farmers already deal with it.

Bob Wilson

 

No, it cannot with hydrogen. Too light, diffuses too rapidly. Big difference between H2 and steam.

You mean like the stuff in our engines? Compressors can be designed (and have been) with decades of lifetime. We already know how to do this because we already use a huge amount of hydrogen industrially.

No, you just design the tank cycling stress to be under the endurance limit. Not an issue. There is one, but that's not it.

And hydrogen is even safer because it diffuses upward so forcefully, and is non-toxic.

 

Hydrogen has a very wide range of flammability. That's a major reason why it's so dangerous.

 

It's not nearly as dangerous as gasoline.

 

And as always,,, It's not a fossil fuel. At least it doesn't need to be produced that way.
It's a great way to store solar and wind 'Peak Production' during long summer days and long windy winter nights.

 

Hydrogen tanks are not light weights. The goal is to get them to the point that the tanks makes of 95% of the tank plus hydrogen weight. So a 5kg tank will weight 95kg when empty. That's the goal, they weigh more per amount of hydrogen now. They also have life spans that aren't much longer than BEV battery packs.

Then the requirements for containing high pressure gases means these tanks take up more space within a car than their volume would imply. The Mirai and Clarity FCEV don't have great trunk space. A plug in hydrogen FCEV will need the space for the tank and large battery.

Farming is not a safe job.

A gasoline spill resulted in minor irritation to my arm that subsided once washed off. If it had been Anhydrous ammonia, it would have been a trip to the hospital for chemical burns with scarring and rehab, with a good chance of burning to the respiratory system.

Which is where hydrogen FCEV might find a niche, though batteries seem to be winning. Then if water is available, the excess renewable electric could be used to make natural gas or even a syn-crude instead.

While I think the hydrogen lobby could be overpromising the public on quick refill times, my main reason against it is the infrastructure. It needs to be built from the scratch, and it will cost more than NG infrastructure. On site production could reduce, but it isn't has efficient.

Renewable hydrogen, and other fuels, will only happen with government intervention, and needs to public behind it.

 

We were at 6% in 2002 with a 7.5% goal. We're well over 5% now. And remember what that means - 5% means you are at about 1,000Wh/kg including the tank and fuel cell. Packaged batteries are 5x worse than that.

 

That internet meme has been debunked. Just look at the fuel economy ratings of the Tesla compared to the Prime, and remember that the Prime is exceptional.

 

What internet meme? That was my own analysis.

 

I know, but you mention it often enough and it so wrong, it reaches the stature of an idiotic internet meme.

The mentioned device uses AT LEAST* 68 kWh of electricity to move a hydrogen clarity an EPA 67 miles.
For the arithmetic challenged, call that 1 mile a kWh. Are you seriously trying to convince us that a Tesla Model S LR consumes 1 metered kWh every EPA mile ? That would be ~ 33 MPGe, but the EPA reports 130 MPGe.

As for your "analysis" that purports to model fuel consumption rate increases as kWh are added, actual results turn it into a joke. ~ 40 more kWh increased fuel consumption per mile less than 2%.
And that difference was all on the highway; the city fuel economy is the same -- the cycle where increased mass should matter the most.



*The 68 kWh per Kg hydrogen figure does not include the energy required to make 4 liters of RO water (presumably < 10 ppm grade) per Kg hydrogen

 

This is snapshot of fuel cell vehicles in time and by no means a call to end research. I also support fusion and nuclear power reactor research. Rather, it is a call to look clearly at where we are today from www.fueleconomy.gov :

• Compared to ICE and ordinary hybrids, 99% of the market, fuel cell vehicles have superior performance.
• Compared to BEC and plugin hybrids, 1% of the market, fuel cell vehicles have a problem.

If fuel cell vehicles can displace ICE and ordinary hybrids, they are friends. But this snapshot in time doesn't bode well. The FCV operational costs are ~2.5 times higher than the Model 3 and ~1.7 times higher than our favorite plug-in hybrids. For customer's motivated by operational cost, FCVs have a long way to go.

Bob Wilson

 

How so?

How is a 10,000 psi pressure vessel filled with hydrogen safer than an unpressurized gasoline tank in a car? What if that tank ruptures in an accident or is engulfed in flame? Instead of something that just burns you now have an explosion. Sounds real safe to me.

 

And what are the costs and lifespan for those tanks? The Mirai is using 5.7% tanks that appear to be 15 years before end of use date. https://ssl.toyota.com/mirai/assets/core/Docs/Mirai%20Specs.pdf

Then there is still the bulkiness of the tank to to address. Still need space for a battery. Which will be sizeable if the car is a plug in.

Without subsidies, those FCEVs cost much more than most PHEVs available.

The tanks are quite robust, and an explosive rupture isn't likely to happen. Which doesn't mean the tank can't take off like a rocket under the right conditions. Extended time in a fire would be bad, but they are carbon fiber which is an insulator. The hydrogen won't heat up as rapidly as when it is in a steel tank.

 

Does anybody know what PSI is required for hydrolysis grade water made from RO ?

 

Gasoline tanks are not tough at all, leak easily, the liquid goes under the car and then sets the entire car on fire.


Vehicles


Hydrogen tanks are tough, a leak diffuses like crazy, the leak goes up and away and any fire is above the car where it does no harm.