OT: Hydrogen Powered SUVs are Here

Is not the big problem with using it, the storage of hydrogen? Its a very small molecule and even in a normal tank it eventually all manages to escape. It is also hard to keep enough. Fuel cells need another gas, usually oxygen. Then the output is water at the end which ever way you go, ie electric or internal combustion directly Most fuel cells still get hot, which wastes energy just like ICes do. Then of course you have to realise that it takes electricity and water to make oxygen and hydrogen in the first place, which admittedly could come from renewable sources. The problem is every time you change energy from one form to another you lose some to operate the process.

Brian

Could it be charged simply by towing, or is that not catered for?

In theory, and probably in practice but nearly every manufacturer advise against it, possibly because charge rates and duration could be higher than that charging system is designed to cope with. They probably could be designed to do it safely but that would cost extra.

Tim

When Green Flag came out to recover my car, it had to be loaded onto a lorry as it was too heavy to be towed. I think he said the maximum he could tow with his van and an A frame was about 2 tonne. I suspect the same would be true of a lot of EVs.

another problem might be: putting an EV in neutral

Would a towed EV want to use regen braking, unless it was fully turned "on"?

Most EVs (especially Hybrids) use some form of planetary gearbox, it might need to provide energy to e.g run one of the planet/ring/sun gears forwards to enable the motor generator to run backwards for charging?

Would the towing vehicle appreciate the towed EV doing constant regen braking to charge itself?

If the traction battery was low the 12V battery would probably still be okay so the system could boot and regen would work.

As far as I’m aware, just a simple reduction gear in EVs.

I’m not sure towing vehicles have feelings. ;-). For sure the drag would be increased, but not beyond what a tow truck/car could manage.

Tim

I don't mind (much) sitting a few litres of petrol in my garage. We know how to handle that, and it's not a major risk.

Hydrogen though? I really don't like the idea that the garage could fill with hydrogen, which IIRC is explosive at anything between 2% and 80% in air. And could be lit by a thermostat or a light switch.

I've seen the R101 films.

Andy

Yes. Hydrogen is a high risk - although simple roof vents let it dissipate quickly.

Are any of the current proposals using H2 as a fuel for an Internal Combustion Engine? I thought that was very inefficient in terms of range per tankful and the only way to make H2 useable is to use it in a fuel cell to generate electricity for an electric drivetrain. Have I missed something?

The advantage that

The argument put forward for converting exiting ICE cars to burn hydrogen is the energy and resources needed to replace them with new fuel cell or battery cars.

Make more sense to convert cars to run on LPG which is way easier than hydrogen which has terrible physicochemical properties for an ICE. Will still produce CO2 but less than petrol or diesel.

Tim

COP27 (under pressure from gulf states?) seems to have redefined LPG as a "low pollution" fuel

That only really makes sense for classics, or for heavy machinery where the engine is secondary to the hauling / digging / harvesting / etc functionality. They can often last for decades.

For your average economical hatchback, run it on petrol or diesel until it falls to bits (which it will before too long) and replace it with an electric. If you're going to be manufacturing a car anyway, you only need to pay the extra energy/resources cost of manufacturing an EV compared with a petrol car (which is roughly a year of use of that petrol car).

Theo

Maybe new cars are still affected by the chip shortage.

What's the main difference between plug-in and self-charging hybrids?

Nt just chips. Wiring looms were often made in Ukraine.

With a plug-in one yu recharge the battery from external mains. A self charging one uses the ICE to charge the battery.

AIUI, part of the concern is that there simply is not enough of some of the raw materials needed to make enough EVs to replace all the ICE cars on the planet.

Another answer might be to look at different ways of using a fuel like hydrogen. For example, the Jaguar concept car that used two micro gas turbines as onboard chargers for a much smaller battery pack. Gas turbines can burn just about anything you can get into the combustion chamber. They don't like variable loads, so are not really suitable for powering a car directly, but they are very good at driving generators.

I would have thought catalytic conversion to methanol would be a better bed. Easily stored, easily/efficiently used in an ICE. There are (I think) some fuel cells that can use methanol.

Lithium, iron, phosphorus, copper. Most of which aren't that scarce. In some cases there currently isn't enough extraction capacity, but that's because nobody needed it - that capacity is scaling up.

Some current EVs use lithium-ion batteries with manganese, nickel, cobalt in them, but that's because they're originally developed from laptop cells where size is a limit above all else. MNC has higher energy density but lithium iron phosphate is less susceptible to catching fire, so what you lose in energy density you save in battery protection. MNC will probably find a niche at the 'performance' end of the market and most cars will be LiFePO4. Most of China's output is already, for example.

A lot of this stuff is engine and fossil fuel companies desperately scrabbling around trying to find ways for their business not to be wiped out. Why bother with that stuff when you can just have a battery and an electric motor?

(there are some niches where batteries don't quite make sense - eg long distance trucking - and maybe those concepts have a place there. But that's typically not where they're being touted)

Theo