OK, so you can store 57 kg of H2 in ~ 1.03 tons of dibenzyltoluene, so ~ 5.7% h2 by weight in a liquid carrier.

This will require 570 kwh heat to get the H2 back out of it, and you re left with the dibenzyltoluene to recycle in a closed system.

Anyone care to calculate how much you would need to drive a fuel cell car 500km?
Or how it compares to Nh3 ?

The three major constituent parts of a BEV are:
a) battery
b) e-motor
c) inverter.

Battery
Regressing to the Parthian Galvanic Cells of ancient Egypt over 2500 years ago, it can be safely stated that more progress has been achieved in the development of cells in the last thirty years than in the accumulated centuries before. Compared with modern cells, the Parthian Cell was of primitive conception, structure, and extremely inefficient. Irrelevant of the present accomplishments and SOA, there is still vast potential for the improvement of such cells. R&D has pointed out the roadmap to be followed for achieving this vast potential; worldwide competition is speeding this progress up. The first to achieve this goal will be rewarded for their efforts. The most important attributes of future cells are: three to five times more energy density, substantial increase in power density enabling faster charging, lower weight, and lower prices in comparison to cells of SOA.

E-Motor
The most commonly implemented e-motor is the radial flux type (RFM). The magnetic flux is oriented perpendicular to the axis of rotation. The axial flux type's (AFM) magnetic flux is oriented parallel to the axis of rotation. Magnetic leakage of the AFM is less than that of a RFM subequently making it more efficient. The torque of an AFM can easily be increased by increasing the radius of the location of the magnets from the center of the rotating axis. The simple formula for determining the torque is T=FxR (T=torque, F=magnetic force, R=radius).

One of the leading manufacturers of AFMs is YASA. This company has been wholly purchased from Mercedes but remains independent in its management, R&D, and production policies.

Renault has taken a 21% stake in Wylot, a french enterprise, also engaged mainly in R&D and manufacture of AFMs. Apparently, Mercedes and Renault seem to be the only automobile manufacturers that have become aware of the opportunities by employing this motor type in their production profiles. It is not only that an AFM offers higher efficiency, additionally, a simple increase in torque can eliminate a reduction transmission lowering system complexity, cost and weight.

Judging accordingly to the available information, it seems that Wylot has mirrored the rotor / stator arrangement and allows the conclusion that this demonstrates an improved solution compared to the original YASA configuration.

Inverter
Presently, many semi-conductor devices implemented in inverters are made of silicon-carbide and have contributed to an overall inverter efficiency better than 99%. There is a tendency to replace silicon-carbide with Graphene semi-conductor devices. These would lower heat losses in an inverter to a negligible level and result in an efficiency close to 100%.

It can be assumed, that once all improvements presently in the pipeline have been employed in production, H2 technology will have as much a chance in future personal mobility as ICEs or a snowball in hell.

@yoatmon is correct as far as H2 for “personal mobility”. Green H2 is more expensive than current forms and as @Davemart points out does not offer much better efficiency than current combustion technology.

However, there are at least two Mobility Areas that H2 might make sense if zero carbon is required: Rail and Maritime, and LOHC could work.

Rail could use LOHC (even Fuel Cells), though an H2 Combustion Engine with Waste Heat Recovery (WHR) to Dehydrogenate the LOHC may be more economical. This should be pursued where Rail Electrification is not feasible.

Maritime may be the best use of LOHC. Marine diesels are very efficient and WHR would work well here also.

Here are a couple of references if you would like to go deeper.
“Siemens Tests LOHC Technology For Hydrogen Trains”, https://www.environmentalleader.com/2021/07/siemens-tests-lohc-technology-for-hydrogen-trains/
“Liquid Organic Hydrogen Could Facilitate Hydrogen as Propulsion Fuel”, https://maritime-executive.com/article/liquid-organic-hydrogen-could-facilitate-hydrogen-as-propulsion-fuel

@Gryf

The dichotomy between the supposed efficiency of batteries vs fuel cell vehicles used as a sole metric is fallacious.

You need power when you need it, and factors like ease of fuelling and the ability to have a supply when you need it are equally important, as are factors like difficulties in ramping battery supplies, although I am entirely in agreement that this is temporary.

The notion that the only way of doing things is to lug around hundreds of kilos of battery or have limited range, as well as the notion that those ( the majority of the world's motorists ) who practically speaking not only cannot but will never be able to conveniently charge at home should put up with being stuffed is nonsensical.

Batteries and fuel cells go together superbly well, with none of the redundancy needed in PHEV ICE vehicles.

Hydrogen, unlike gasoline, does not sour in the tank, so is available for months or years after filling up.

The average commute here in the UK as around 8.5 miles.

So for many, who can charge at home, it may make sense to have a modest battery, perhaps of the order of 10KWh or so,, but with a fuel cell and hydrogen tanks so that you simply continue ZEV driving when that runs low.

Although keen to note that average, as opposed to exceptional, driving distances are only 30 miles or so, battery only people never seem to pick up on that that makes a nonsense of their arguments for efficiency, as you would only be using hydrogen when needed.

If efficiency is really the only, or at least the predominant metric, then those routinely going much further could have a rather bigger battery or drive a BEV, in spite of charging times.

Yep, a fuel cell vehicle is somewhat more complex, but OTOH inherently purifies the air, and if simplicity were the only metric, then construction would be using shovels only, not mechanical diggers.

If you want to go local and can conveniently charge, use a battery for your everyday running around.

If you want to go a distance, simply pump in some hydrogen.

If the figures given for average daily distances travelled by battery enthusiasts are correct, and they are, then they have blown away their own argument about the need for big batteries for long distance for most people.

A 10KWh battery pack and fuel cells in most vehicles is just fine for efficiency, and sticking in expensive batteries to knock that up to 75KWh or so is not sensible

Correction: A PEMFC requires a hundreds of kilograms of Fuel Cell, carbon fiber tank plus a 10 kWH battery.
A Toyota Mirai weighs and a Tesla Model 3 Long Range both weigh around 4300 lbs.

@mahonj,
I don't know the details of this system, but speaking broadly, this type of processes use heat exchangers to recover the heat.
Once the hydrogen has been recovered from the hot liquid, you don't need it hot any longer. So you pass it through a HX to preheat the incoming cold liquid.

To put my above argument for making fuel cells a fairly substantial part of the mix, lest I be thought a mere advocate, as so many are for BEVs, there are many places where BEVs are far better placed.

That is because most of my above arguments apply to areas like Europe, Japan, and the US/Canada, where seasonal variability is high, so supplying renewables on demand is tough, and cold weather etc is a real range problem.

That is where most pricy cars are bought at the moment.

The situation out to around 2050 and on is very different.

Most of the world's new motorists will be added there, where seasonal variability is low, from India to South America and Indonesia to Africa.

And by some time before then, battery hassles should be overcome.

So:

ttps://techxplore.com/news/2023-01-solarev-cities-pathways-decarbonize-equitably.html

' A research group has recently crunched the numbers on implementing an energy system employing solar photovoltaics (PV) on rooftops combined with electric vehicles (EV) in Jakarta, finding a wealth of economical and environmental benefits. In the analysis, EVs were used as batteries for the variable PV generation.

"Through the widespread usage of rooftop PVs combined with EVs as batteries, there will likely be a 75–76% reduction in CO2 emissions, and the PV/EV system can provide electricity to the city at a price 33–34% cheaper than Jakarta's existing energy system in 2030," said Professor Takuro Kobashi, who led the research.

The group discovered that solar panels already provide a cost-effective means to generate electricity within the city. These savings, which as of 2019 stood at 3–4%, will rise to roughly 8–15% by 2030. When factoring in the use of EVs as a battery for PVs (e.g., Vehicle-to-Home or Vehicle-to-Building systems), where PV electricity stored in EV batteries can power cities as well, the rooftop system could meet 75–76% of Jakarta's electricity demand with clean and affordable electricity.'

That is a completely different ball game to throwing money at big battery BEVs in high latitude countries with great solar variability.

The EVs WHERE THERE IS LOW ANNUAL VARIABILITY can economically provide storage.

I don't advocate FCEVs as a panacea.

But BEVs aren't., either, and immoderately pushing them everywhere at any cost is throwing money away.

@sd

There are umpteen subsidies and mandates driving the sticker price of BEVs, with companies allocating costs to spread them across ICE cars to hit mandated targets.

That is why only Fiat now offer Class A cars in Europe, out of the big boys.
So the most economic cars were driven out of the market.

One way and another, I think Stellantis's estimate of around a 40% cost increment against ICE is about right.

And here in Europe, fuel savings are mostly due to exemption from fuel excise duty.

It is perks, mandates and subsidy driving BEV sales, not real competitive costs.

That will change, and the differentials narrow, but that is not anytime soon.

@sd said;

' I will say it again. Without taking into account any subsidies or tax rebates, it is flat out less expensive to buy a new Chevy Bolt with a 260 mile electric range than it is to buy a new Toyota Prius and the Bolt is also considerably less expensive to operate. '

You might say it again, but you still don't provide any data or context for your claim.

No doubt taking just the purchase price, ignoring the mandated uptake of BEVs in California etc which forced adoption of BEVs with the excess costs loaded on to other vehicles and so on, what you say is true.

But that tells us almost nothing more generally.

Utah is not the centre of the motoring industry universe, nor can costs there be simply read out as applicable elsewhere.

Gasoline costs a fraction of what it does elsewhere in Utah, which is favourable to the comparison, but as against that in places like Europe it has been very specifically stated that exemptions from fuel tax have a limited shelf life, and electric cars are going to be hit by taxes per mile driven.

To be clear I have no doubt that at some point as batteries develop, the total costs will be lower than for ICE, with equalised taxation everywhere, even excluding the very substantial benefits of reduced GHG.

But in the long run we are all dead.

A hybrid or a plug in hybrid is at minimum competitive with a long range BEV most places, with equal incentives, and in many places ex subsidy and mandate it way more do-able and practical.

That is going to change, but unless you are spending other people's money, timing is all important.