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US schools can subscribe to an electric bus fleet at lower prices than diesel

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Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#281

Post by iancmceachern »

headmelted wrote: post #246
VBprogrammer wrote: post #169

Earlier quoted context omitted.

> diesel buses breakdown regularly In comparison to what? Diesel engines in commercial vehicles are extremely reliable. It certainly could be possible for an electric bus to be more reliable, they certainly have less points of mechanical wear. However, there are a lot of power electronics going into charging their batteries and delivering the battery power to the motors.

Diesels, in general, are notoriously unreliable. The only very selective myth I still hear repeated is that diesel engines are more durable now than they were, which isn’t saying much, and skirts around just how much else can and regularly does go wrong with a diesel-powered vehicle. Flywheel clutches are an expensive nightmare, and the vibration destroys manifolds, cams and exhausts in short order. That’s only for t…

Not true. There are diesel engines that have warranties up to half a million miles.

The old ones "run on physics"

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#282

Post by bsdetector »

hedora wrote: post #210
bsdetector wrote: post #179

Earlier quoted context omitted.

This video is actually a great example of how smart people can fool themselves. The sources he uses for breakeven time (DOE) assumes 24.3 mpg [1] for the average regular car, but people don't drive average cars they drive specific cars. If you take the DOE assumptions and approach this from the other end, CO2 pollution by mpg, then you find an ICE car getting approx 30 mpg or more is less polluting per mile driven th…

There are many, many assumptions to such calculations. Here's PG&E's best guess at g CO2 / kWh based on time of day/year in California (page 2): https://ww2.arb.ca.gov/sites/default/files/classic/fuels/lcf... If you only charge from noon to two in Q1, then use have zero marginal emissions per mile driven (this is the best case). If you only charge from 7-8pm you emit 142.06 gCO2e/MJ. 1 megajoule = 0.2777777778 kilowa…

If you just apply CA's 49% natural gas (according to DOE) to the 45 mpg for 100% natural gas you come up with a gas-burning car needing >90 mpg to be cleaner -- well higher than the 70 mpg you calculated vs charging on natural gas -- but easily achievable with hybrids.

I feel like there are many people who see 30 coal / 45 nat gas and take offense that it doesn't make EVs sound particularly good. This is why I called it a more honest presentation because EVs in terms of CO2 are fairly bad in WV and marginal in DE or MI or many other places compared to a high-mpg regular car. Instead of taking offense and setting out to correct the record, understand that not sounding particularly good is an accurate view.

Even in CA, the mpg needed to be cleaner than EV formulation makes it clear that driving a 100 mpg hybrid for instance is so good that any further gains are of little consequence.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#283

Post by cure »

drewcon wrote: post #264
VBprogrammer wrote: post #261

Earlier quoted context omitted.

If Diesel engines are so unreliable why are they used in practically every heavy goods vehicle, bus, tractor, plant equipment, ship and backup electric generator in operation today?

Torque.

Which, incidentally, is also something electric motors are far superior at (flat curve...).

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#284

Post by erosenbe0 »

stephen999 wrote: post #249
erosenbe0 wrote: post #224

Earlier quoted context omitted.

I have found measuring in typical American neighborhoods that PM2.5 is raised the most when people burn wood for recreation or heat in the evening. It is much higher in the evening with a few neighborhood fire pits than during rush hour with a few diesel vehicles around. This is also when residents have asthma symptoms too. To be fair they are more likely to be home. So it is not cut and dry but if possible I would l…

So what? You can try and clean up both. Particulate is not the only pollutant either. NOx and ozone are also emitted from diesel cars.

Agree, just saying vehicle emissions are part of the picture and more work needs to be done on air quality.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#285

Post by skolsuper »

derriz wrote: post #239
skolsuper wrote: post #203

Earlier quoted context omitted.

And maybe as the type of generation used for the marginal difference in energy required. If your country generates 90% of its electricity from hydroelectric and 10% from coal, you might still use coal for the comparison because hydroelectric power would be slow to add and the extra electricity for EVs would have to provided by coal

Assuming that it's more likely that marginal demand will be met by coal than by renewables makes no sense to me. Coal is rapidly been retired as a source of electricity generation - 85% of generation capacity being retired in 2022 will be coal[1] - and there hasn't been a new large coal plant built in the US for over a decade[2]. In Europe the amount of electricity being generated by coal is half of what it was at it…

Still... if you plan to add 100MW of renewable this year and retire 100MW of coal, then demand goes up by 100MW, do you now add 200MW of renewable instead, or do you delay the retiring of the 100MW of coal?

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#286

Post by mike_d »

me_me_mu_mu wrote: post #205
lucastheisen wrote: post #188

Earlier quoted context omitted.

what is a reasonable walking distance? 9% seems like a surprisingly small number.

Just looked at CDC website it says fewer than 20%. Suburbs have been the only place where I’ve seen lots of yellow busses because everything is so spread out. Idk where that dude got his numbers, go to any city in the USA and you'll see kids taking public transit to school aka walking. https://www.cdc.gov/pcd/issues/2016/15_0573.htm#:~:text=Esti... .

> go to any city in the USA and you'll see kids taking public transit to school aka walking

The majority of children do not live in cities. Most people move to suburban/urban areas when they have kids.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#287

Post by elihu »

tshaddox wrote: post #234
elihu wrote: post #233

Earlier quoted context omitted.

> They also have to have at least one extra bus and driver on standby every day because diesel buses breakdown regularly during a route and they have to go out with a second bus and pick up the kids and finish the route. I distinctly remember being one of those kids that would have to be picked up in another bus every once in awhile. This was before cell phones, so the bus driver had to walk to the nearest house (thi…

The buses in my small town all had radios (and quite a bit of chatter between drivers, as I recall). Were you in a district with very long distances or geography where that wouldn’t have been feasible?

My bus route wound over and between a couple of hills, so a radio might not have worked.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#288

Post by kube-system »

olivermarks wrote: post #277
kube-system wrote: post #228

Earlier quoted context omitted.

That's a demonstration of a $99 harbor freight flux core welder, not a "battery fire" This is a EV fire: https://www.youtube.com/watch?v=CdaFk3w6rUY And this is a diesel school bus on fire: https://www.youtube.com/watch?v=0nPrUdP_POg If any vehicle catches on fire, you have to leave the vehicle, or risk death. There is no "safe fire"

Again, I suggest you digest 'Lithium-Ion Battery Fires in Electric Vehicles - Safety Risks to Emergency Responders' from the US NTSB which is analysis of types of EV vehicle fires. https://youtu.be/J6eS6JzBn0k The 220v mig welder example was to demonstrate the different fire characteristics of a trapped/runaway energy battery fire vs gasoline fire. All commercial vehicles such as school buses have a significant fire…

My point is that both will kill. There are, of course, some differences between fires of different types. However, one thing remains constant: the occupants can be killed by any of them if they don't get out.

I definitely agree that manual locks are safer -- school bus emergency exits don't even have locks, they simply only have latches on the inside. This isn't a problem with batteries though -- this is a problem with Tesla.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#289

Post by sagarm »

humanrebar wrote: post #267

What is the range on these? In rural area, yellow busses need to travel for two hours morning and night. And for extra-curricular activities, like transportation to away games, drives can last five hours or more.

Most Americans don't live in rural areas.

Re: US schools can subscribe to an electric bus fleet at lower prices than diesel

#290

Post by headmelted »

iancmceachern wrote: post #281
headmelted wrote: post #246

Earlier quoted context omitted.

Diesels, in general, are notoriously unreliable. The only very selective myth I still hear repeated is that diesel engines are more durable now than they were, which isn’t saying much, and skirts around just how much else can and regularly does go wrong with a diesel-powered vehicle. Flywheel clutches are an expensive nightmare, and the vibration destroys manifolds, cams and exhausts in short order. That’s only for t…

Not true. There are diesel engines that have warranties up to half a million miles. The old ones "run on physics"

There absolutely are high warranty Diesel engines. That doesn't mean they'll last that long - a lot of those warranties are subsidised by servicing.

Even with that said (and as detailed above) there are so many other parts to a modern Diesel-powered vehicle that can and regularly do go wrong that they get a pass for because it's not in the engine block. I do wonder if this is because people just assume the vehicles are otherwise identical beyond the engine.

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