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The other difference between trucks and cars is that power/weight isn't really important for the latter, and hugely important for the former. If there's an impr
by kackerd 5y ago
The other difference between trucks and cars is that power/weight isn't really important for the latter, and hugely important for the former. If there's an improvement that allows you to carry 5% more weight in your car, that doesn't matter much. Most of the engine's energy is being used transporting the engine around, and the weight of passengers and luggage is not an operative constraint. For trucks it matters a lot, because they just became 5% more efficient.
- nostromo 5y agoCrazy idea: don't store hydrogen as a liquid but as a gas. Hydrogen is lighter than air, so you've just reduced the fuel requirements by making the semi lighter than it otherwise would be. Or just go to the logical conclusion: make semis blimps that use hydrogen to both float and as a fuel source.
- xxpor 5y ago... you're aware a variation of this was tried a century ago, yes?
- nostromo 5y agoYes, but tech has improved a tad since then. In every flight you take, the wings are filled with highly combustable materials, and yet we find ways to keep them from exploding. The same is true for all those batteries in electric cars, and of course gasoline.
- xxpor 5y agoJet A is really not that combustible; it's very close to diesel/kerosene. If you take a lit match and drop it in a bucket of Jet A, nothing would happen, it'd just burn out. It's way safer than gasoline. It's combustible only when turned into a fine mist. On the other hand, H2 would have exploded just from the spark of lighting the match.
- jsight 5y agoYou'd likely get by with dropping the match into gasoline most of the time too. Its not definite that there will be vapor from it in the right mix for it to catch fire before hitting the surface. Gasoline also isn't quite as combustible as people imagine.
- nostromo 5y agoIt's worth noting that hydrogen fires burn bright and quickly, but tend to not be very dangerous to people. Gasoline and batteries are heavy and tend to stick to surfaces (including people) when they burn, almost like napalm. Hydrogen rushes upwards, away from people and surfaces, as it burns, and is generally quickly exhausted.
- linuxftw 5y agoI strongly disagree with this statement.
- jsight 5y agoI'm not sure what there is to disagree with. Fire around gasoline is dangerous for a number of reasons, but liquid gasoline pooled just isn't as volatile as people imagine. The vapors are different. See both sides of this coin here: https://www.youtube.com/watch?v=DsZOE1nvlhI https://www.youtube.com/watch?v=DsZOE1nvlhI Also, this: https://www.youtube.com/watch?v=vln5-HZpgcA https://www.youtube.com/watch?v=vln5-HZpgcA Don't try this at home. Vapors can change things dramatically and horribly. The videos lightly demonstrate this too, but it can be worse.
- linuxftw 5y agoLiquid gasoline without the present of vapor is pretty much nonexistent. Dropping a match into some is going to be a problem.
- throwaway0a5e 5y agoIn my experience the combustibility of det fuel and similar petroleum products depends primarily on whether the context of the conversation is praising modern safety engineering or heckling someone for using diesel as a cleaning solvent.
- istjohn 5y agoYou haven't made them lighter, you've made them more bouyant. A ton of feathers weighs the same as a ton of rocks, but a ton of rocks is far more aerodynamic.
- JoblessWonder 5y agoI mean, this is sort of off-topic.... but I just love this video: https://www.youtube.com/watch?v=-fC2oke5MFg https://www.youtube.com/watch?v=-fC2oke5MFg
- nostromo 5y agoSure, but the point is a more buoyant semi would lose less energy to friction between the tires and the road.
- trulyme 5y agoYou're missing the point. Liquid hidrogen takes much less space, that's all. It is neither lighter nor heavier than the same amount of hidrogen gas. And for buoyancy to matter, the trucks would need to be huge (zepelin style).
- deleted 5y ago[deleted]
- HPsquared 5y agoThat works until there's a light breeze.
- the_pwner224 5y agoAnd if you have 20% less weight on the wheels, you now have 20% less traction and thus 20% (or more?) longer braking distance. You still need the same engine output to accelerate 100 tons, but you only have the traction you would get from an 80 ton load. That's a bad thing. Meanwhile, you save a miniscule amount of energy by having less-loaded tires. Anyway, you need to compress hydrogen to store any meaningful amount, which increases the density and makes it like a normal gas/liquid instead of making you more buoyant. So it's not even possible.
- NwtnsMthd 5y agoIt becomes a bit of a transport density problem. A semi does not take up much more room than the cargo it's transporting (if fully packed) but a blimp needs to be significantly larger to carry the same amount. They're big, slow, and require a large amount of space to land on the ground. It just seems like more issues to overcome than hydrogen fuel cell trucks.
- bloopernova 5y agoCould trains tow blimps?
- kevin_thibedeau 5y agoThe trailer tail aerodynamic devices are supposed to save 5% on fuel. They remain rare and 99% of those are left undeployed. The trucking companies don't seem to care much about easy cost savings.
- Dennip 5y agoFrom looking at it on Google images, could it be that this device has other downsides? Making doors more awkward to open, increasing turning radius etc?
- bombcar 5y agoA significant percentage of semis you see are nowhere near fully loaded. Especially for local deliveries- the truck is often half-empty.
- zeristor 5y agoDon’t you mean half-full?
- anshorei 5y agoWhen you're doing deliveries half-empty is the optimistic take.
- tomcam 5y agoCan’t leave me hanging, brofus
- tosser456123 5y agoDon't you mean twice as big as it needs to be?
- bombcar 5y agoThe marginal cost of dragging 40ft of air is so small compared to the hassle of trying to determine which truck is the correct one for today’s deliveries and pickups, so the companies tend toward having all trucks the same size.