Hydrogen availability

[98elise]

anonymous said:

[redacted]

Surely you know that FCEV is already a FC/BEV "Hybrid"? Hydrogen cars need a battery because a fuel cell is not suited to sudden energy demands.

anonymous said:

[redacted]

If one was 3x more efficient than the other then one would dominate. There would still be edge cases for the one that wasn't efficient, but that would be it.

[anonymous-user]

Improvements in the efficiency of hydrogen production and delivery infrastructure are there to be made, are being made and will vastly change that well to wheel efficiency.
Electrolysis of hydrogen from water will be one major factor. Dirty source to clean source too.
A localised electrolyser will improve efficiency.
Improvements in the transportation and storage techniques of hydrogen will improve that efficiency.
Economies of scale will bring the cost down.

Another little company nobody has heard of.
https://www.itm-power.com/markets/hydrogen-fuel-st...
Recent investment drive generated more investment than asked for.
£1.3 billion market cap.
British (this coming from a country that's behind the game relative to others).
Now car refuelling is one of many areas they cover. That's key, that hydrogen will be finding its way into many, many areas as well as just cars.
So the cost of hydrogen will come down and the efficiency of production and delivery will improve.

Now thinking about the car, FCEV will offer more potential for weight saving (or weight mitigation when increased range is desired) than BEV. The energy density of hydrogen is far greater than batteries. This will improve the tank to tarmac efficiency of the car.

For people who want or need the range freedom and flexibility that FCEV will offer over BEV, the well to wheel difference will be so far mitigated that that argument will just represent some adenoidal moaning minnie droning in the background.

Edited by anonymous-user on Sunday 25th October 10:43

Edited by anonymous-user on Sunday 25th October 19:29

[GT119]

You forgot to mention that the higher energy density of hydrogen is of course offset by the weight and volume of the pressure vessel and the weight and volume of the fuel cell and battery that is required.
Additionally, battery energy densities are not a fixed value like an element, they will continue to improve with the passage of time.
The energy density argument doesn't hold a lot of water.

[98elise]

GT119 said:

You forgot to mention that the higher energy density of hydrogen is of course offset by the weight and volume of the pressure vessel and the weight and volume of the fuel cell and battery that is required.
Additionally, battery energy densities are not a fixed value like an element, they will continue to improve with the passage of time.
The energy density argument doesn't hold a lot of water.

Weight is also less of an issue in BEV's due to regen. Additional energy is used to accelerate, but then additional energy is recovered.

[anonymous-user]

Do you know what the energy density difference is between the two?

[GT119]

Yes.

However, back to the engineering aspects (once again), it's the kerb weight of the vehicle that matters though, the difference between a BEV and a HFCV of equivalent range is not really that significant to the energy efficiency when regenerative braking is taken into account.

[otolith]

The opportunities for improvements in the efficiency of the hydrogen fuel cycle are limited by thermodynamics. The only technological advance I can imagine making much difference is low pressure solid state hydrogen storage, but that’s still unusably crap for road transport.

[Gary C]

SWoll said:

Is the issue not that for FCEV to be a genuine alternative for those use cases where it's suggested BEV doesn't work the infrastructure would need to expand massively and offer genuine national coverage?

But as those number of use cases is already limited and likely to become more so as EV charging options expand and range/efficiency continues to improve who is going to invest in the FCEV infra for a diminishing number of possible users?

It just seems to be too late to the party to become viable?

If there was enough of a driver for commercial HGV's to develop a hydrogen manufacturing and distribution system, then that might enable FCEV's

So, is there a big enough driver to push FCEV HGV's ?

[anonymous-user]

GT119 said:

Yes.

However, back to the engineering aspects (once again), it's the kerb weight of the vehicle that matters though, the difference between a BEV and a HFCV of equivalent range is not really that significant to the energy efficiency when regenerative braking is taken into account.

Please let me know the energy density comparison, battery Vs hydrogen.
And how effective do you think regen braking is over long distances on the motorway.?

[98elise]

anonymous said:

[redacted]

Why would a Hydrogen Car be any lighter than a BEV? The Mirai and a Model 3 are similar sized, yet the standard Model 3 is lighter.

Weight also doesn't factor much at a constant speed. All the energy used is in overcoming losses from rolling resistance and drag, not the weight of the car. The weight is a factor in acceleration and deceleration (regen)

[GT119]

anonymous said:

[redacted]

Let me try to dig out the white paper I wrote in 2009 when these discussion were relevant.
It could take me a while to find it, so bear with me.
As for your second sentence, neither weight nor regen is relevant to motorways, what's your point?

[anonymous-user]

Gary C said:

SWoll said:

Is the issue not that for FCEV to be a genuine alternative for those use cases where it's suggested BEV doesn't work the infrastructure would need to expand massively and offer genuine national coverage?

But as those number of use cases is already limited and likely to become more so as EV charging options expand and range/efficiency continues to improve who is going to invest in the FCEV infra for a diminishing number of possible users?

It just seems to be too late to the party to become viable?

If there was enough of a driver for commercial HGV's to develop a hydrogen manufacturing and distribution system, then that might enable FCEV's

So, is there a big enough driver to push FCEV HGV's ?

I think so. Decarbonisation is the driver for all EVs. There's massive decarbonisation potential with HGVs.
The nature of HGVs, operating over long distances, pulling a lot of (paid for) weight, time sensitive journeys, means that FCEV would be vastly more suitable than BEV.

To achieve longer range you could keep adding batteries but the batteries are very heavy. More and more work would be done shifting the vehicle's own weight. The chassis would need to be toughened up to take this extra weight and that would compound the issue further! This would impact efficiency, tank to wheel.
With hydrogen, to get more range, you add more or larger tanks for the hydrogen but you don't necessarily add more of the other components. So with FCEV you can get a longer range and lighter HGV.

There is also a cost advantage to the production cost of a long range FCEV where the production cost curve for BEV is steeper than for FCEV as you increase kWh capacity. I think BEV production cost overtakes FCEV somewhere near 55kWh because of the batteries.

Beyond that there's the downtime element and time flexibility requirement of the industry. FCEV refuelling for an FCEV HGV would be far, far quicker than for a BEV HGV and there's no need to factor in downtime for refuelling, hours at a time. We know fast charging reduces the working life of a BEV and slow, low current charging just wouldn't suit the HGV industry.

[jjwilde]

So has Kampff convinced anyone on this thread of hydrogen?

Because this thread has actually taught me even more about why it is a terrible idea.

[anonymous-user]

anonymous said:

[redacted]

[anonymous-user]

jjwilde said:

So has Kampff convinced anyone on this thread of hydrogen?

Because this thread has actually taught me even more about why it is a terrible idea.

You've got to be some kind of bot.
Seriously weird.

[GT119]

anonymous said:

[redacted]

Geez you mind works in a strange way.
You originally said that energy density is important, I was pointing out that it's not as important as you are making out.
Yes I know FCEV can utilise regenerative braking, it's somewhat irrelevant though to a point that the weight of either type of vehicle is not so important when regen is utilised.
So if weight isn't that important (to either) then why is energy density....

[anonymous-user]

Weight IS an important factor in the efficiency of ALL vehicles.
It's a fundamental thing!

Energy density is a factor in that consideration.

Edited by anonymous-user on Sunday 25th October 17:22

[anonymous-user]

Simple solution to motorway HGV range when they are BEV:




The Siemens eHighway:

https://www.dailymail.co.uk/news/article-7003989/T...

[Gary C]

Max_Torque said:

Simple solution to motorway HGV range when they are BEV:

We can't even electrify all our railways, let alone the motorway network

Interesting idea.

[GT119]

I'm at a loss...

You are now arguing strongly that weight is important to efficiency, which of course implies efficiency must also be important.

Yesterday you were arguing that the poor comparative efficiency of HFCVs to BEVs isn't important.

Here's a question for you, what is the airspeed velocity of an unladen swallow?

As far as weight goes, comparative kerb weight matters to some degree for start-stop driving (tempered by the ability to recover energy used to accelerate the vehicle). For constant speed, the drag coefficient and drive train efficiency are far more significant.