The Economist: Electric cars Difference Engine: Tailpipe truths

Psuns has correctly pointed out that a 10 kg H2 tank weighs 400 pounds, not 800 I had posted earlier. Corrected numbers below

LOL. One more time

(estimates, all)
Hydrogen energy/mass is about 3X that of petrol
A hydrogen tank to carry (10 kg=22 pounds of fuel) weighs 400 pounds
A petrol tank to carry (30 kg=66 pounds of fuel) weighs 60 pounds

Equal energies ( about 1200 MJ), the respective weights are
Hydrogen (chemical + tank) = 22 + 400 = 422 pounds
Petrol (chemical + tank) = 66+ 60 = 126 pounds

So...
For these energy amounts, the hydrogen car's energy (fuel+tank) weighs about 3.35x a petrol car's (fuel+tank). For someone who thinks Ethanol is bad because its energy density is 30% less than petrol, this arithmetic that shows Hydrogen (plus its container) is 70% less energy dense than petrol must be having fits LOL

 

Honda with 3.9 kg tank gets 60 miles per kg. 240 mile range.

Quantum 5 kg usable hydrogen tank weighs 202 lbs.

Honda with Quantum tank 5kg vs Honda 3.9kg would have 300 mile range.

Estimates none. Facts all.

 

All me to convert to Kg and gallons

The Honda (fuel+tank) weighs 96 Kg
----

If a petrol car, the tank is 27 kg, leaving 69 kg for fuel
Petrol weighs about 2.8 kg/gallon, so the petrol car would have a 24.6 gallon tank. In a Prius that is a 1230 mile range.

 

The problem is that a quantum 5kg H2 storage tank weight is over 90kg of weight. see http://www.qtww.com/assets/u/129LTankBrochure.pdf

So for your FCX, 95kg of tank + fuel = 300 miles.

The Prius's gas tank weights less than 10kg.

so for 95kg you could carry
17*5kg = or more than 1400 miles..

Meaningful energy density per unity weight really needs to include the mass of the tank needed to store at that density.

 

I have been using 27 kg for the fuel tank. That must include the fuel LOL

 

Figured it would be about the same as the Quantum tank.

I guess you could put a 24 gallon tank on the 50 mpg Prius. Not sure what problem you are trying to fix.

The 5 kg tank on the 60 miles per kg FCX works fine for 300 mile range. I'd prefer 7 kg for a 430 mile range. I want to make it from PDX to Whistler without stopping in Seattle for H2. Tanks, range, miles per are all in kg for hydrogen vehicles.

Being able to have a hydrogen generator in the garage running off of solar/wind power purchased at green/night rates from utility or home solar panels and using the tap water to make fuel would be soooo cool.

 

None.
We are just pointing out to you that the energy density of hydrogen stinks, once you remember to weigh the tank the car has to carry. And remember Trollbait's calc, that the hydrogen tank is twice the volume of a petrol tank for the same energy amount. Take that out of your back seat or trunk space.

These are the minor problems with hydrogen, and they already should give you pause in your advocacy.

 

The FCX gets 60 miles per kg including weight of the tank which is 4 kg capacity. Whatever the weight of the tank and fuel, it's all bundled into the 60 miles per kg. Just as tank and fuel are bundled in Prius 50 mpg.

It doesn't matter if the cat is black or white, only that it catches mice and gets good mileage doing it.

Quantum tank has slightly higher capacity of 5kg useable which would give the FCX a 300 mile range. Doubt a 7kg tank would weight much more than the 5 kg or affect the FCX's miles per kg.

 

Oh no...you've gone in the ditch again.

Hydrogen has the highest energy density of any fuel short of antimatter at 123 mj per kg vs. gasolines 47 mj.

I think the point you were trying to make is this creates some problem in fuel storage in a car but the FCX demonstrates it is not a problem.

 

+1

:deadhorse:

I'm betting this will lead to a PC first . . . a newbie hitting 5,000 posts in one year ... primarily on vaporware.
.

 

Not according to the road test article-- 2 weeks is a COMPLETE loss of fuel in the tank, not 14%. http://www.wired.com/cars/energy/news/2006/11/72100?currentPage=1

Sorry, but a car that loses fuel when parked is just absurd.

 

You yourself said earlier that the tank to hold 5 kg of hydrogen weighs 90 kg.

What *is* your problem ?
On second thought, don't answer that. Welcome to my ignore list

 

Kind of like a Prius that can't be driven after being parked two weeks unless you put a charger on it? Similarly, one of the solutions BMW had was to burn the hydrogen to run the AC to keep the H2 tanks cool during storage. Neat trick.

Remember BMW took a basic BMW7 and converted it to hydrogen to prove the concept. Honda engineered the FCX as an H2 car.

 

202 lbs for the Quantum tank which holds 5kg of useable hydrogen.

None. That works fine in the Honda. Gives it a slightly greater range up to 300 miles than its existing 4kg tank was the point if range was an issue. It also showed that increasing the range was easy to do.

Range and refill was the genesis of the discussion on H2 vs. EV as the reason for the EV "not being ready for prime time" per Toyota were the issues of range and refill.

H2 cars don't have those issues and Honda building out the H2 pumps at existing gas stations is part of their and the government's pilot program on feasibility of H2 cars.

 

You don't know the Prius very well.

Mine was in storage for 3 months. Fired right up.

All I had to do is disconnect the 12V batt before I put it in storage. No need for chargers.

Again, a car that loses all of its fuel after 2 weeks of being parked is just absurd.

 

My bad on the Explorer/Escape mix up. Must be because of your Escape harping in the other thread. Or just that you would think a car or truck would actually haul around half it's weight in fuel.

The 6 gallons difference between the Escape and Explorer fuel volume adds 36.4 pounds or 16.5 kg. Assuming the Explorer had the largest gas tank.

"Ha! He made a mistake that had no bearing on his point. I can continue to ignore hydrogen's poor energy density along with the massive size weight of its tanks."

Energy density - Wikipedia, the free encyclopedia

It isn't just the weight you ninny. Cars are not TARDISes. They aren't bigger on the inside. Those 2 more kilograms of hydrogen will take up over 13 gallons of space. Not including the tank. Go down to the store and buy 13 gallons of milk, and place them in your car where they won't be in the way of passengers and cargo. People complain about the loss of trunk space in hybrid trims of ICE cars. They bitched about the loss of the spare in the PHV.

Not true of the few non-SKS Prii out there. The SKS system can be turned off on the gen2 to prevent it. The 12 volt can be replaced with something better. More importantly, it isn't an issue with a regularly used car.

BMW's tank leaks whether you use it or not. People aren't going to buy a car that leaks fuel they spent cash for.

Didn't think I,d use use outside of the politics section.

 

I am not a fan of FC-ICE but I think FCHV will be a great alternative. Here is Toyota's assessment of:

Well-to-wheel Efficiency


Refueling Speed


Fuel Cost and Infrastructure Effectiveness

 

In regard to the weight, FCHV-adv weights 4,145 lbs (1,880 kg) with 472 miles range (JC08 cycle) while Highlander Hybrid weights 4,641 lbs (with V6 ICE).

 

The issue was range. Point of the Explorer example was its 350 mile range was similar to FCX of 300 with a 5kg tank.

1 more Kg actually the Honda tank is 3.92 kg. Space and weight not an issue as the Quantum tank is equal in wt and size. As the Honda (and BMW) demonstrate, the hydrogen tanks were not an issue. Tank technology is moving faster than battery. Batteries weigh in at 455 lbs (?)?

No free lunch.

Nope. Only if car sits for extended period and hydrogen starts to warm up. Doesn't happen with regular use. BMW talked about burning the H2 to keep tank cool for extended periods of inactivity.