341–350 of 919 posts
Earlier quoted context omitted.
This gets thrown out quite a bit but I don't really buy it. If it is not designed for alcohol, it probably isn't going to work. Alcohol has too many weird interactions with stuff like aluminum.
Many countries are running on part-ethanol already; the UK is on "E10" (up to 10%)
I just realized how much energy efficiency is being squeezed out of a Tesla. It's incredible. A normal diesel fueled sedan such as the Chevy Cruze diesel runs at about 31mpg, which is 13.2 km/l or 15.3 km/kg. Diesel has a mind-boggling 12700 Wh/kg energy density[1], which translates to an efficiency of ~827 Wh/km for the Chevy. By contrast, the Tesla Model S, has a ~540 kg battery[2]. At 272 Wh/kg (from the posted ar…
>runs at about 31mpg, which is 13.2 km/l or 15.3 km/kg The measurements outside North America are reciprocal, e.g. 7.7L/100km (which is awfully inefficient for a diesel, normally it should be around 5L) So converting gallon to liter, and mile to kilometer is the wrong way to present it. As for the efficiency in general - of course electric engines have a very high efficiency (in the 90s), unlikely diesel which can ba…
Earlier quoted context omitted.
What about charging efficiency?
DC is better then AC and both depends on how much the battery is already charged, temperature of the battery, the infrastructure (charging cables for example). The range is somewhere from low 80's for low amperage AC charging on cold weather using a low quality granny charger cable to high 90's for a warm battery on a dedicated high power DC charger. This of course doesn't include losses in transmission from the powe…
- AC converted to DC (with power factor correction, usually means AC stepped up 1st)
- DC converted back to AC (but higher voltage) and MUCH higher frequency
- AC transformed to lower AC voltage (still higher frequence)
- AC rectified to DC (filtered and stabilized), DC voltage lower
Earlier quoted context omitted.
Why is it so important for you to be able to pollute a bit more when commuting?
First of all, the poster was writing about the legal elimination of an option, which is does not fit such reduction. Some people value the qualities that the current (pun happened) alternatives do not offer: they are inadequate for some use cases. This includes long travel and refuelling in minutes. Furthermore, since societies are now suffering an epidemic of lunacy, electric cars can be extreme noise pollutants, be…
Well, isn't it then peoples choice to do that? Or do you instead argue for a ban of EVs? I don't get this point.
I've never heard an electric car making more noise than the road noise. Which of course is annoying in itself going at high speeds, but still less than an ICE. What you're describing is absolutely not something of the ordinary. ICEs revving their engine in residential streets, however...
Earlier quoted context omitted.
The big reason for this is thermodynamics. A conventional internal combustion engine car has to convert chemical energy to kinetic energy - the absolute best theoretical efficiency of this might be 70%, but in practice it's more like 30%. Electric cars have to pay the same thermodynamic penalty, but they pay it at the power station (In practice, thanks to renewables, not all the electricity used to charge a car will…
> the absolute best theoretical efficiency of this might be 70% I fell down a rabbit hole and found this link, which gives 46% for the theoretical limit for the efficiency of the internal combustion engine. https://physics.stackexchange.com/questions/98966/maximum-th...
Earlier quoted context omitted.
Hybrids that emit carbon will still have a huge effect on global warming, simply because there are so many cars. There isn't a huge amount of headroom for efficiency increases, so you're only going to get anywhere near "net zero" by charging from a renewable grid nearly all the time.
Hybrids almost never emit carbon though. Because they're almost always running from the battery that you charged up from the wall before leaving home for your daily commute. And the daily commute is less, or maybe a little over the battery range. If it isn't then you have bought the wrong car, if you goal is carbon neutrality. You can use a smaller battery, which means using less rare materials that are very expensiv…
Earlier quoted context omitted.
Though that makes me think that hybrids have a real future. Or hydrogen fuel cells. Anything that doesn't require charging directly from the grid all the time, because although parts of the USA and Norway are ready for that, it's very tricky to get right globally. Maybe hybrids like the Prius get to be so efficient that such cars will have a truly negligible impact on global warming.
Hybrids that emit carbon will still have a huge effect on global warming, simply because there are so many cars. There isn't a huge amount of headroom for efficiency increases, so you're only going to get anywhere near "net zero" by charging from a renewable grid nearly all the time.
CO₂ -> C + O₂
2 H₂O -> 2 H₂ + O₂
C + 2 H₂ -> CH₄ (methane)
[1] https://en.wikipedia.org/wiki/Fischer%E2%80%93Tropsch_proces...
Earlier quoted context omitted.
Not that confusing, only the US measures fuel in gallons, isn't it? Everyone else just uses liters.
The UK also does for some God awful reason (especially infuriating considering it's sold by the litre at the petrol station). In the United States and some other countries, a gallon is equal to 128 fluid ounces or 3.785 liters. Meanwhile, in the United Kingdom and some Commonwealth countries, a gallon is equal to 160 fluid ounces or 4.546 liters.
Earlier quoted context omitted.
Well, they were already possible and being sold. But with relatively short but usable ranges. Those now more than double with this battery. Which makes those planes usable in a lot more scenarios. Consider the Eviation Alice, one of the 9 passenger prototype electrical planes that is currently undergoing test flights (i.e. it definitely works). The advertised range is 250nm. Not amazing. But far enough for a lot of r…
> Most flights are short haul. And they are, well, short. Which means, all of those are in scope for electrical planes. Exactly. In the EU, Eurocontrol (European Organisation for the Safety of Air Navigation) says 30.6% of flights in 2020 were 0-500km, roughly within the range of the Eviation Alice currently. A further 43.6% of flights in the EU are between 500 and 1500km. Source [1] > You don't have to cram hundreds…
We may also see a return to more of a hub-and-spoke model. Fly from a smaller, local airport close to you. Fly to some hub near the half-way point, switch to a plane that takes you to a small airport close to your destination. If planes are smaller maybe security can be relaxed too. Total time spent travelling could be comparable to taking a direct flight with a large international airport further from your origin and destination. Then the aircraft doesn't need to be very long range.
Earlier quoted context omitted.
> the absolute best theoretical efficiency of this might be 70% While ICE are heat engines with a theoretical limit of 70%, they’re more specialised subsets described by the Otto (gas) and Diesel (… diesel) cycles, which have a much lower theoretical maximum. Just plugging the temperature ranges into Carnot will give you a Carnot limit of 50%, and using Otto will yield 46% ( https://physics.stackexchange.com/a/98992…
Wrap the combustion engine with a heatpump to a small steam engine?