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Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

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Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#371

Post by valuearb »

emptyfile wrote: post #277
SigmundA wrote: post #268

Earlier quoted context omitted.

Lithium batteries still seem to have a way to go in energy density currently at around 250-300 wh/kg and going up year over year with a theoretical maximum (Sulfur cathode) of above 2500 wh/kg. At around 2000 wh/kg you are equivalent to diesel drivetrain energy density both size and weight based on my rough math. Expensive large hydrogen tanks in a trailer with high pressure lines to tractor seems like it would cause…

I have no clue about batteries or hydrogen tanks. But I'm always amused to think that posters on HN give more credence to their back-of-the-napkin calculations over opinions of, say, folks at Toshiba, Volvo or Daimler.

Smart engineers chose Hydrogen as the first stage fuel fuel the Space Shuttle, and it turned out to be a terrible choice.

H2 offered the highest ISP, ie energy per fuel mass, and originally they wanted the Shuttle to be a single stage to orbit vehicle. But Hydrogen also added larger, much heavier tanks and engines didn’t have enough thrust for that. So they had to add large Solid Rocket Boosters to get off the pad. And all they additional dry mass meant the higher ISP of H2 was wasted.

And now the SLS is repeating those mistakes, not because engineers didn’t learn those lessons, but because politicians require them to repeat them.

Engineers recommending Hydrogen for cars are influenced by regulatory requirements and benefits, and politically by company objectives. If your CEO says Hydrogen is important to use because our government and regulators say it is, you as an engineer will find a way to make the best of a bad choice.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#372

Post by SigmundA »

semi-extrinsic wrote: post #368
Mvandenbergh wrote: post #244

Earlier quoted context omitted.

>It doesn't seem like current fuels cell have much of a energy density / range advantage even though hydrogen itself is much more energy dense, the fuel cell weight and efficiency and high pressure liquid hydrogen tanks must be accounted for. Hydrogen has a better gravimetric scaling than batteries - as stored energy increases, the fixed weight of the fuel cell is amortised over more energy and the weight of high pre…

For trucks and other heavy duty applications, liquid hydrogen starts to win out over pressurized. In LH2 tanks, the scaling becomes advantageous as you are optimizing against heat ingress, which goes down as 1/R when you increase the radius R.

Double walled high vacuum tanks that vent hydrogen gas if left unused for less than day and empty themselves after 10 days.

Liquid hydrogen at -253c that is more energy intensive to make than high pressure.

Not sure I see that being practical.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#373

Post by elihu »

jvanderbot wrote: post #320
SigmundA wrote: post #117

This is at 66.9 km/h (40 mph) in order to greatly increase its range due to lower drag compared to normal highway speeds. As a comparison a Tesla Model 3 got 975km (606 miles) at 40 km/h (25 mph) [1]. I can't seem to find any range tests at a similar speed as the Nexo. I found an EPA dyno test for the Model 3 at 77 km/h (48mph) for 708 km (440 miles). The Nexo and Model 3 have similar dimension and weight and price,…

The one thing H has going is quicker fills at the pump, right? Being low on joules is a pain when you're going to work in the morning, but it's a royal pain if you have to wait a half hour to charge.

On the other hand, if we ever build out electrified road infrastructure, one might be able to recharge a battery electric vehicle without even stopping just by pulling power from rails embedded in the road or overhead power lines.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#374

Post by Gravityloss »

merb wrote: post #367
Gravityloss wrote: post #11

Earlier quoted context omitted.

You don't want your fuel cell chemistry to be contaminated. The fuel cell needs oxygen from the air. That's also why it's so light, since in H2O, 90% of the weight is the oxygen.

> That's also why it's so light, since in H2O, 90% of the weight is the oxygen. which also makes it unsuitable for moon cars.

Or alternately, you can use a lithium battery with air. But it gains more weight as it is used up.

Anyway, energy density is comparable to gasoline.

https://en.wikipedia.org/wiki/Lithium%E2%80%93air_battery

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#375

Post by NoblePublius »

Editor’s note: there is no naturally occurring source of hydrogen and no established industry of producing hydrogen from renewable energy. It’s made from oil and natural gas and exists purely by the grace of the carbon industry.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#377

Post by _carbyau_ »

jfengel wrote: post #341
jvanderbot wrote: post #320

Earlier quoted context omitted.

The one thing H has going is quicker fills at the pump, right? Being low on joules is a pain when you're going to work in the morning, but it's a royal pain if you have to wait a half hour to charge.

At least you get a half hour to think about how you should have plugged it in last night.

For me that'd be half an hour to ruminate on how my apartment has no place to charge a car.

I am not getting an EV anytime soon unfortunately.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#378

Post by crote »

jvanderbot wrote: post #320
SigmundA wrote: post #117

This is at 66.9 km/h (40 mph) in order to greatly increase its range due to lower drag compared to normal highway speeds. As a comparison a Tesla Model 3 got 975km (606 miles) at 40 km/h (25 mph) [1]. I can't seem to find any range tests at a similar speed as the Nexo. I found an EPA dyno test for the Model 3 at 77 km/h (48mph) for 708 km (440 miles). The Nexo and Model 3 have similar dimension and weight and price,…

The one thing H has going is quicker fills at the pump, right? Being low on joules is a pain when you're going to work in the morning, but it's a royal pain if you have to wait a half hour to charge.

Even there it's not a clear-cut victory.

The last time I looked at it, it turned out that hydrogen filling stations need a significant time after fueling each car to get back to transfer pressure. If you want to fill your tank right after someone else, you'll have to wait for a bit.

But overall, filling time is not that big of a deal. Most people don't really drive that much, and the car spends the majority of its time in a parking lot. In practice it turns out that just charging it at home every day is more than enough to keep a battery full.

In addition to that, commercial vehicles often have a driving time limit. As long as the recharge period is shorter than the mandatory break, you are not going to care about the recharge speed.

And both battery capacity and charging speed are quickly improving. There might be a small niche for hydrogen, but it's disappearing rapidly.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#379

Post by Retric »

emptyfile wrote: post #277
SigmundA wrote: post #268

Earlier quoted context omitted.

Lithium batteries still seem to have a way to go in energy density currently at around 250-300 wh/kg and going up year over year with a theoretical maximum (Sulfur cathode) of above 2500 wh/kg. At around 2000 wh/kg you are equivalent to diesel drivetrain energy density both size and weight based on my rough math. Expensive large hydrogen tanks in a trailer with high pressure lines to tractor seems like it would cause…

I have no clue about batteries or hydrogen tanks. But I'm always amused to think that posters on HN give more credence to their back-of-the-napkin calculations over opinions of, say, folks at Toshiba, Volvo or Daimler.

I once called BS on a VR article written by John Carmack on HN and he clarified the article. https://news.ycombinator.com/item?id=17348638

Which umm shows you never know who’s posting here.

Re: Hyundai Nexo sets new world record 887.5 km travelled on single tank of hydrogen

#380

Post by abakker »

semi-extrinsic wrote: post #366
abakker wrote: post #273

Earlier quoted context omitted.

With hydrogen this is especially problematic due to hydrogen embrittlement. https://en.wikipedia.org/wiki/Hydrogen_embrittlement

Nope, because you don't make hydrogen tanks out of materials that are susceptible to hydrogen embrittlement. In particular, pressurized automotive-size hydrogen tanks aren't made from metal at all, they are typically epoxy/kevlar/carbon fiber composites.

OOC, since you know what these tanks are made out of, what is the duty cycle/lifespan of those tanks? I was presented some info on Kevlar tanks for drones using fuel cells and remember thinking that the lifespan was very short.
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