Electric Vehicles (Cars, Planes, and Ships)

So I have been attempting to estimate how (un)safe battery-powered aircraft would be, by comparing accident rates.

4 incidents between 2006-2013 due to lithium battery issues minus one ground fire vs 4 incidents between 2006-2014 due to fuel-fed fires minus one lithium fire. Tiny numbers but I am only considering these incidents in Aviation Safety Net, which presumably exclude laptop fires that are quickly put out and the EgyptAir flight 814. Given that jet fuel is present in considerably larger quantities on any plane than lithium batteries, that's not reassuring especially when considering that batteries needed for electric aircraft will likely have much higher energy densities.

Edited by SeptimusHeap on Apr 4th 2021 at 10:10:13 AM

For a minute there I thought you were talking about cars when those have much higher rates of gasoline fires. Aviation fuel is surprisingly difficult to spontaneously ignite, which is a very good thing, and airplane engines are generally much better maintained than gas ones. By battery fires, are you talking about in the aircraft's avionics and airframe or are you talking about batteries in luggage or carry-ons?

Edited by Fighteer on Apr 4th 2021 at 3:24:11 PM

Avionics, airframe and cargo - the statistic somehow does not include luggage and carry on battery fires which are apparently quite common [but usually trivial, except for the aforementioned EgyptAir flight]. However, normal aircraft don't use many batteries except as backup for critical systems and I don't think these need to have a high power density.

Added the word "aircraft".

Theoretically, I think that batteries are inherently less safe than jet fuel for the following reasons:

• Aviation fuel only needs to burn in the engine when it's in vapour form, so it's possible to make it highly inert in liquid form which is the form that jet fuel is stored in the tanks. Batteries by contrast need to produce energy when in the racks and thus are more fire-prone there.
• Lithium batteries are notorious for projectile-like behaviour when they burn, which jet fuel lacks.
• There are far more metaphorical "moving parts" in a battery than in a fuel tank and thus far more things that can break and start a fire. Moreover chemical flaws in fuel stop mattering once that batch is burned, while a battery keeps its flaws.
• A fuel-fed plane loses weight as it burns its fuel, which makes landings - both normal and emergency - easier and safer. A battery-fed plane by contrast keeps the same high weight.

But I wanted to know if this theoretical analysis has any empirical support yet.

Getting lighter as fuel is consumed is a serious advantage and one that's very difficult to overcome for high-performance scenarios like aircraft and especially rockets. No matter how efficient batteries become, we will never be able to make rockets powered by them, although that's kind of a silly observation since a rocket requires throwing stuff out of a nozzle and it makes no sense to physically hurl the batteries.

Batteries can power ion drives and that sort of thing, but those don't have anywhere near enough thrust to get to orbit. Before someone brings up Rocket Lab's Electron, that uses battery-powered pumps, which is a good application for smaller rockets but doesn't scale well.

Anyway, regarding aircraft, I do not have a good sense for the relative safety of batteries vs. jet fuel, but I should also point out that internal combustion engines have had a century to develop while battery-powered aircraft are relatively new. One would expect safety margins to increase as the technology matures.

Tesla has revealed the target date for opening of the Giga Berlin factory. Along the way, it sent a letter to German authorities sharply criticizing them for their slow process of issuing final operation permits, stating (paraphrased) that climate change won't wait for bureaucracy.

I was trying to find a discrete article; here's one by Drive Tesla Canada. It's covered widely enough that it should be easy to find corroboration. This article discusses the letter itself, which is German but in translation reveals July 2021 as the target start date of vehicle production. In addition to an auto factory, Tesla is building a battery plant in Germany intended to produce 100 GWh of cells per year.

Edited by Fighteer on Apr 8th 2021 at 11:23:02 AM

Since we've talked about it here before, there's more news from Las Vegas about The Boring Company's tunnel system. It's very close to being ready for business: moving people around beneath the strip and avoiding street traffic. Article by The Review Journal

This is the first operational commercial tunnel by The Boring Company, although it has many more projects in the pipeline. Up until now, no public images were available save for some tweets by Elon Musk, but now journalists have been invited inside and given the opportunity to take rides. The lights were set to psychedelic mode for the event, because of course they would be.

The Las Vegas Loop plans to use up to 60 Tesla vehicles - we saw Model 3 and Model X in the videos - in a closed system. They will be fully autonomous eventually; for now each car has a safety driver. You will hail a ride with your phone much like taking an Uber. There are plans for 16-passenger vehicles at a later point.

Since the cars are all-electric, there is no need to provide special ventilation for car exhaust and the risk of fire is significantly reduced. Should a breakdown occur, there are specialized vehicles capable of clearing it out.

There are major advantages to tunnel systems like this, not the least of which is cost. Conventional tunnels cost more than $1 billion per mile to build, while The Boring Company does it for around $10 million: 100x savings. Part of the savings is in the reduced diameter. The tunnels just need to be able to fit a single driving lane with some slack. Part of it is that, as mentioned above, ventilation is much simpler with all electric vehicles. The drilling machine itself also helps reduce cost by taking the waste and forming it into construction materials.

Lest anyone wonder about this, earthquakes are much less dangerous in tunnels than above ground.

Edited by Fighteer on Apr 9th 2021 at 8:20:50 AM

The last time there was a discussion on that project in this thread there were concerns that the company wasn't taking the possibility of an incident in the tunnels seriously and there thus were inadequate safety and rescue measures.

Having said that, having a way to mass produce tunnels regardless of the surrounding rock would be a huge step for environmental protection measures. Imagine how cities could look if we could shift all roads, traffic etc. underground and repurpose open spaces.

[At least in the case of car tunnels, I think it's been proven that accident rates and mortality are less than on open roads. Sure, rescuing someone in a tunnel is harder and woe betide you if you are caught in a fire ... but there is no icing, fog, rain, snow or glaring sunlight in a tunnel and thus accident rates are less]

"We should make the tunnels the diameter of a single vehicle" still seems short-sighted. First, you've now introduced all the flaws and limitations of that which plague a railway system (you can never make wider vehicles for any reason), and second when something does break down you've backed up the entire system until you can get to it. Which you have made much harder, because it's one lane wide.

If it's exactly two cars wide then you've at least reduced that (maybe), but you still can't do wider vehicles otherwise it comes back. Wouldn't you want two lanes?

Edited by RainehDaze on Apr 9th 2021 at 2:45:31 PM

For one thing, since all the cars are using automation on a fixed track (the simplest case for automation), there would be virtually no risk of driver error causing crashes. The loop is closed so some yahoo can't butt in off the street. There are no gasoline engines so a much lower risk of fire from a breakdown and fewer breakdowns in general. The cars have self-diagnostic software so if they encounter issues they can automatically report them and take themselves out of service.

Combined, these should reduce the risk factors from a typical tunnel by a factor of at least 100. I'd say the biggest challenges will be human factors: people vandalizing the cars or (given that it's Vegas) getting sick in them.

The article says that there are emergency vehicles designed to reach and service any cars that experience issues, but assuming it's not a catastrophic problem the safest action would be to continue to the next stop rather than halt in the middle of the tunnel. If that's not possible, what you'd do is have all vehicles ahead of the problem proceed to their stops, then run your service equipment in backwards.

Edited by Fighteer on Apr 9th 2021 at 10:00:33 AM

I would imagine that there are parallel access tunnels to assist emergency personnel in reaching the scene of any accident, but I dont know.

See, that's the thing; it's going to happen a lot less, but it will happen at some point. You've minimised the up-front cost whilst making anything that does go wrong an annoying delay to fix. Then you've got the limitations on your future options etc.

It's a bizarre marriage of the worst parts of cars (small occupancy, not all that much room) and trains (when something does break or go wrong, you've created a backup that affects everyone in the system; you can't add more throughput easily).

All choices involve compromises. What alternative would you suggest? Should we continue to build highway bypasses? Downtown traffic jams? Carbon burning cars? Change carries risk, but stagnation carries more.

Not building as small as possible and ignoring the many, many times this has caused headaches down the line.

And considering that if you're basically building a small train loop, only using cars as the vehicles, maybe you shouldn't bother with the car part?

Edited by RainehDaze on Apr 9th 2021 at 3:29:02 PM

Cars are a stopgap until more dedicated vehicles are built. However, ultimately these kinds of tunnel will be designed to serve commuters, who will drive their personal vehicles (or their robo-taxis) into the system and exit the other end. They will be electric-only, of course, and will operate on automatic in the tunnels with humans there only to supervise.

There is a tendency among some to make the perfect the enemy of the good: to insist that nothing be done until the technology is perfect. There must be a balance struck: if you can make things ten times better now but there's still some risk, is it not obligatory to move now?

Edited by Fighteer on Apr 9th 2021 at 10:35:12 AM

So you want a larger tunnel with a train. I'd settle for access service tunnels and emergency exits.

This implies that making the tunnels this size was a necessary and forced constraint. Also, this still sounds like reinventing the train, but introducing extra inefficiency and material waste. It's pretty weird.

I would have just thought "make it two lanes wide" would have been the obvious choice.

Are you a tunnel engineer? By "two lanes" I presume you mean an unused emergency access lane—otherwise I don't see the point. I tried to find something online about traffic tunnel construction, but so far there isn't much. I'll keep looking. Meanwhile, we shouldn't assume that we know exactly how these tunnels are designed. I would hope that Nevada safety regulations would prohibit an underground tunnel with no emergency access. That sounds so implausible that I would assume there is someway of getting people out should they become stuck.

If you had two lanes going each way, and total control over the access to the tunnel, then that gives you one redundant lane to keep operation (if something breaks) and provide access, as well as the obvious "we can fit more in here either because there's more demand than anticipated or because things got slightly bigger", albeit at the cost of that redundancy. Doesn't solve the emergency access though.

IIRC the Boring tunnel has emergency access at various points along the tunnel. Making it wide enough for multiple vehicles increases the cost for a marginal increase in safety, but neither you nor I are tunnel engineers so we need to trust the people who are.

I would rather distrust them and try to find what the justifications for their choices are by asking. Being an unrelated forum, the closest I can do is speculation.

Edited by RainehDaze on Apr 9th 2021 at 3:58:38 PM

I know that many long tunnels (Gotthard Road Tunnel [cars] and Eurotunnel [trains]) are with two tubes, one for traffic and the other for rescue operations and the like. Do note though that the traffic tube in the Gotthard Tunnel is two lanes but in opposite directions so that we can have bidirectional traffic with one tube but that creates lots of safety issues. The Gotthard Base Tunnel [trains] has some intermediary spots with refuges and has two tubes, one for each direction.

I'd imagine one consideration is that since trains carry more people per train than cars, you need fewer of them. Thus the number of potential accidents is less and with only one or no fuel tanks [for electric trains] the fire hazard is less than for cars too. So train tunnels need fewer safety measures than car tunnels.

I'm still curious if there is a better justification for this being a car tunnel other than "to sell more Tesla vehicles".

The electric vehicle requirement simplifies the ventilation system by a huge factor. It's pretty obvious: if you operate a gasoline engine in a tunnel you need to get the fumes out. You also need to supply a lot more fresh air to feed the engines. Having no flammable liquids in the tunnels cuts fire risk by a huge amount.

To suggest that someone would go to all the effort of creating a tunneling company just to generate demand for something that is already selling every unit that can be produced is kind of crazy, but okay. Bang that drum all you like.

The actual motivation is traffic mitigation. As Elon says, we plan road transportation in two dimensions when our world is three-dimensional. Building up is difficult, so why not build down?

Edited by Fighteer on Apr 9th 2021 at 11:51:14 AM

To be fair to Tesla and Musk, I did give a rationale before:

Also consider that self-driving solutions are much simpler when you are in tunnels.