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We Could Have Had Electric Cars from the Beginning

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Re: We Could Have Had Electric Cars from the Beginning

#241

Post by magduf »

chadcmulligan wrote: post #141
amelius wrote: post #139

Earlier quoted context omitted.

For short distances you could use a bicycle or scooter instead. Cars are mostly useful for larger distances, i.e. on highways, where slow vehicles are not allowed.

bicycles / scooters have a limited application though - families with young kids, long trips, older people, people with injuries, its raining, are just some of the groups / times these are excluded. Cars still are superior general purpose solution for travel.

>bicycles / scooters have a limited application though - families with young kids

In Japan, bicycles routinely have child seats, and frequently two child seats (front and back).

Re: We Could Have Had Electric Cars from the Beginning

#242

Post by LifeLiverTransp »

gambiting wrote: post #138
raxxorrax wrote: post #135

Earlier quoted context omitted.

I still think there is a limit in chemical density that cannot be overcome without significantly changing technological principles of current batteries. Maybe hydrogen fuel cells would be a better solution after all if we can find an efficient way to contain it. Easier said than done...

Energy density of hydrogen per litre is few orders of magnitude lower than that of petrol. Really the only saving grace of hydrogen vs batteries is the speed of refueling.

Dont you forget something- hydrogen if hydrolizes takes place in situa - aka directly below a windpower or solar-plant, has the lowest conversion loss right there.. Also storage can be improved by now chemically - meaning you bind it to a https://en.wikipedia.org/wiki/Hydrogen_storage#Liquid_organi...

and reduce that to a nearly solid material with extremly high energy density. Its okay to be a tesla fanboi, its not okay to propagate ancient technological "insights".

Re: We Could Have Had Electric Cars from the Beginning

#243

Post by avar »

magduf wrote: post #234
godelski wrote: post #129

Earlier quoted context omitted.

Another reason: Even today the energy density of batteries is SUBSTANTIALLY smaller than that of fossil fuels. [0] We frequently see this graph [1] showing how far batteries have come (they have! and we need to keep going) but not understanding this is part of the issue too. [0] is why we need to keep researching, but [0] is why electric was never going to win in the beginning. It is taking very advanced materials to…

>Another reason: Even today the energy density of batteries is SUBSTANTIALLY smaller than that of fossil fuels. That's irrelevant. The thing people keep forgetting with fossil fuels is that most of that energy is being wasted to just produce heat. With an EV, 95-98% of the battery's energy is being used for propulsion (unless you turn on a heater of course). In short, you're comparing apples to oranges.

It's not irrelevant. The high water mark for Li-Ion efficiency is 0.875 MJ/kg[1] (in practice e.g. a Tesla seems to be 0.7 MJ/kg). For petrol that's 46.4.

Now, let's adjust that for the efficiency of the power train. Let's give the electric car 100% (in practice it's 95-97%). Production ICE engines are around 20%. That gives us 46.4 x 0.20 = 9.28 MJ/kg.

That's a 10.6x difference in favor of petrol if we take the optimistic 0.875 number. The most fuel-efficient cars sold today consume around 5L/100km. A liter of petrol is 0.78 kg. A 1000 km of range is the probably holy grail for an electric car.

A a car powered by petrol needs to carry 39 kg of fuel at the start of a trip for that range. That'll be at best ~390 kg for the Tesla at its theoretical limits, which isn't counting overhead weight associated with the battery pack, and unlike a petrol-powered car the weight doesn't reduce as you go through the trip (a significant hurdle for e.g. electrically powered airplanes).

Of course the power train of an electric car is lighter than on the ICE-power vehicle, but the ICE still wins, and all of this is before we get to the battery needing much more volume than petrol, although as the Tesla shows you can win back some space by placing it in the floor, which isn't a realistic option for ICE.

None of this means electric cars aren't viable, but the weight and volume differences for the same MJ are inherent, and aren't going to go away.

1. https://en.wikipedia.org/wiki/Energy_density

Re: We Could Have Had Electric Cars from the Beginning

#244

Post by adrianmonk »

sitkack wrote: post #124
adrianmonk wrote: post #111

> Early electric cars performed better in cities than internal combustion vehicles This article talks a lot about cars around 1900. In the US in 1900, 60% of the population lived in rural areas and only 40% lived in cities. (See https://en.wikipedia.org/wiki/Urbanization_in_the_United_Sta... ) So working well in rural areas was probably a more important concern. A product that works OK for all your potential customer…

85% of all the income was probably made in cities.

Valid point. I couldn't easily find data on that, though I do think that at a certain point cars became one of those things you find a way to afford (even if you don't have a lot of money) because of how useful they are if you live in a rural area.

Re: We Could Have Had Electric Cars from the Beginning

#245

Post by gnu8 »

magduf wrote: post #234
godelski wrote: post #129

Earlier quoted context omitted.

Another reason: Even today the energy density of batteries is SUBSTANTIALLY smaller than that of fossil fuels. [0] We frequently see this graph [1] showing how far batteries have come (they have! and we need to keep going) but not understanding this is part of the issue too. [0] is why we need to keep researching, but [0] is why electric was never going to win in the beginning. It is taking very advanced materials to…

>Another reason: Even today the energy density of batteries is SUBSTANTIALLY smaller than that of fossil fuels. That's irrelevant. The thing people keep forgetting with fossil fuels is that most of that energy is being wasted to just produce heat. With an EV, 95-98% of the battery's energy is being used for propulsion (unless you turn on a heater of course). In short, you're comparing apples to oranges.

That heat is not wasted if you live in a place that has seasons. I’d like to see EVs with a petrol burning heating system that could provide cabin and battery heat during winter. Many gas stations sell untaxed kerosene that I think could be used because it’s for heating, not motor fuel.

Re: We Could Have Had Electric Cars from the Beginning

#246

Post by clouddrover »

magduf wrote: post #236
clouddrover wrote: post #158

Earlier quoted context omitted.

> Really the only saving grace of hydrogen vs batteries is the speed of refueling. And range, weight, and (eventually) price. Batteries need to improve in all these areas. Fuel cell cars are expensive at the moment because they're produced in such low volumes. But Toyota thinks that if they produced FCEVs at scale they could build them cheap: https://www.thedrive.com/tech/26050/exclusive-toyota-hydroge...

Toyota is the only company pushing hydrogen as a fuel for cars, and it's puzzling why, because they really don't have many advantages, and a ton of disadvantages compared to BEVs. Everyone else is working on BEVs, including the Chinese.

Hyundai is working on fuel cell cars as well:

https://www.electrive.com/2019/06/05/hyundai-to-sell-their-f...

Re: We Could Have Had Electric Cars from the Beginning

#247

Post by C1sc0cat »

benj111 wrote: post #198
C1sc0cat wrote: post #191

Earlier quoted context omitted.

I think you mean Bikes (ridden by middle class white people) not Scoters and Mopeds ;-) In India you can see entire families, Dad, Mum and Baby on Mums back riding a moped.

Flying pigeons are bicycles. I'm not a biologist but I believe non white, non middle class people are capable of riding bikes... Even women! :P

Wooosh as you miss the point totally

Re: We Could Have Had Electric Cars from the Beginning

#248

Post by C1sc0cat »

magduf wrote: post #240
C1sc0cat wrote: post #152

Earlier quoted context omitted.

They are popular in Asia because relatively speaking Asia is poor. Just like the flying pigeon bike was massively popular in china back in the 70's, I even saw one being ridden at Cranfield university by a Chinese masters/doctoral student in the late 70's early eighties.

No, Japan is one of the richer countries on the planet per-capita, and bicycles are very popular there. They're popular because they're cheap and simple and they have excellent public transit for longer distances and they don't have to worry much about thieves like in crappier countries. And as a result of people biking and walking more, almost no one there is fat, unlike America where the majority of the population…

Um I think they meant asia ex Japan as did I

Re: We Could Have Had Electric Cars from the Beginning

#249

Post by nostrademons »

tigershark wrote: post #221
nostrademons wrote: post #136

Earlier quoted context omitted.

You run into Carnot cycle [1] physical limits. The efficiency of any heat engine is bounded by 1 - Tc/Th, i.e. the ratio of the absolute temperatures of the cold reservoir (usually the exhaust gases) to the hot reservoir (combustion temperature). To make an engine more efficient, it needs to run as hot as possible. Non-superheated steam engines are bounded by the boiling point of water (373 C); assuming 21 C outside…

Water boiling temperature is 373 K, not Celsius. 21 C of the air temperature is 294 K.

Ah yes. I labeled it wrong, but the calculation was done with 373K hot reservoir & 294K cold reservoir temperature.

Re: We Could Have Had Electric Cars from the Beginning

#250

Post by mhh__ »

sokoloff wrote: post #205
hwillis wrote: post #200

Earlier quoted context omitted.

> It seems like you responded only to the gravimetric density part of the chart and not the volumetric part of the chart. Gravimetric (specific energy, Wh/kg or MJ/kg) energy is generally more relevant than volumetric (energy density, Wh/l or MJ/l), because batteries are about twice the density of gasoline. Weight is also more valuable than volume in most vehicles, and a battery system already takes up hardly any mor…

> If you want to talk about power density, an electric battery will beat a gas engine to absolute shreds. Most (all?) production electric cars struggle to do a full power complete lap of Nürburgring Nordschleife without heat-related issues. They're amazing at the Stoplight Grand Prix (and I enjoy my cheap LEAF daily), but struggle as racecars. >> I'm not aware of any performance cars that weigh twice as much as their…

Not hugely related but VW have sent their electric hill climb car around the ring (6:05)

https://youtu.be/lRHIiJjWhWo

Very very fast although its not a racing car per se

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