Question of the Month: Which technology will power automobiles in 20 years?

Interesting question! I'm not sure about hydrogen being energy source for the everyday car

If an ICE engine is 25% efficient,  you are making use of approximately 8MJ/L of the energy in gasoline. So assuming a hydrogen powered drivetrain is 100% efficient. It would seem you would need the same volume of liquid hydrogen as gasoline to travel the same distance. SUVs have 80L gasoline fuel tanks. Not sure...  

Interesting question! I'm not sure about hydrogen being energy source for the everyday car

If an ICE engine is 25% efficient,  you are making use of approximately 8MJ/L of the energy in gasoline. So assuming a hydrogen powered drivetrain is 100% efficient. It would seem you would need the same volume of liquid hydrogen as gasoline to travel the same distance. SUVs have 80L gasoline fuel tanks. Not sure...  

With modern containment vessels, it would be as safe to use as gasoline and a whole lot less volatile as lithium.

A hydrogen powered drive train will not be 100% efficient - the kind of fuel cell which might be used in cars is only about 40% efficient (better ones exist but molten carbonate technology is unlikely to be feasible in a car). The electric parts of the drive chain won't be perfect either - estimates vary but 90% seems fair. So the hydrogen  car will manage 36% v 25% - an improvement but not enough to make the tank smaller.

And  I don't fancy liquid hydrogen , one warm day too many and ....... at best the tank vents itself - or do we have to factor in the cryogenic cooler in the garage ?

MK

Riding a 3000PSI tank of natural gas(methane), gives me the heebeegeebees too.

Though kudos to the people who made it happen.

https://www.cycleworld.com/motorcycle-news/bajaj-freedom-125-cng-powered-motorcycle/

Right now nat gas is selling at $1/GJ, which is equivalent gasoline being 3.8 C/L (thermal equivalent)

If only it were that price in the UK, it's about £1 per therm = £10 per GJ.

MK

It would be fair to say that creating hydrogen at the moment requires a fair amount of energy (electricity) and a hydrogen powered vehicle takes that hydrogen and converts it back to electricity for the vehicle to use.  It's more efficient to just use electricity in the first place.

Undoubtedly.

I am not a believer in the hydrogen economy.

This thread is a year old now and right at the beginning I made my pitch for synthetic fuel. Nothing has happened in the last 12 months to make me change my mind.

MK

That is true, but the battery issue with electric vehicles kills the goose.

They take time to charge, waste a lot of energy in heat, and generate even more heat when used to move the vehicle.

When you add in the convenience issues, hydrogen will always beat electric using batteries.

EV charging is somewhere between 80% and 93% efficient with the remainder lost to heat, conversion and other inefficiencies.  Fast DC chargers are more efficient than 7Kw home chargers where more loss is incurred in the conversion from AC to DC.  I’ve tried (quickly, not exhaustively) to find out how much heat is generated by the battery under use.  Obviously the harder the vehicle is driven the warmer the battery gets but it would seem that not enough heat is generated by the battery to recycle into warming the cabin.  Instead, this has to be managed by a heater or through the use of a heat pump (quite common on newer cars) or, presumably, a combination.  In fact, for efficient charging in colder weather the battery needs pre-warming.  I would presume in hot weather it may need cooling for efficient charging.  In any case the vehicle does not lose a lot of efficiency in wasted heat.  An EV is vastly more efficient than a petrol/diesel/hydrogen vehicle.  Hydrogen will never beat a pure electric vehicle because they BOTH use electricity to drive the vehicle.  Hydrogen isn’t directly burned to provide motion, it is used to create electricity in the vehicle to provide motion.  Producing hydrogen is also energy intensive.

They do take time to charge, obviously, particularly in relation to a fuel-delivery system.  In the majority of circumstances, this isn’t actually an issue, but I can imagine it is a pain when (a) chargers are busy and waiting for access is factored in; or (b) in an emergency waiting for 30-40 minutes may feel like an eternity.  There have certainly been a few horror stories about charging times.

What Michael says about fuel delivery infrastructure is true; if synthetic fuels can be produced that can be delivered through existing infrastructure and are as clean (at point of use) then I think that may be a great alternative even if not as efficient.