How green are electric cars

[JI_Joe84]

In response to the OP's point, this mathematically makes sense. I use to work in a power plant as an engineer myself, and I can tell you in a pure efficiency sense, it's actually better in terms of pollution output to burn something like gasoline or natural gas at a heating/automotive source than take electricity from a power plant.

However, this is IN THEORY.

In reality, I'm not entirely sure this holds up. It really depends on emissions controls at power plants vs. automobiles. And that I can't really speak to other than power plants.

Coal power plants these days have environmental emissions control systems, including scrubbers, baghouses, etc. to catch stuff within limits set by the EPA. Not saying their not still emitting stuff into the air, but it's not everything produced.

So you'd have to take into account what is ACTUALLY being released rather than what is theoretically being released. And that's a facility by facility calculation.

Just saying, it's more complicated in reality.

At the time "Eco boost" engine's became the norm for cars I found out that the combustion efficiency of a turbo charged piston engine was up to 60 percent with naturally aspirated piston engines getting up to 30 percent. What I ponder is what is the combustion efficiency of turbine engine's such as those used in power plants. Axial flow turbines are God in aviation but that has a lot to do with it's power to weight ratio and it being in general a very arodynamicaly clean package I suspect.

[Simon_Jester]

We know how much fuel and carbon emissions are associated with generating a kilowatt-hour of electricity. We know how far an electric car can drive on that kilowatt-hour. We know how many gallons of gasoline it would take to cover the same distance, and how much carbon emission is associated with that.

That's all we need to know. Numbers like raw percentage efficiency of one kind of engine versus another are at best irrelevant and at worst actively misleading.
_______________________________

That said, yes, efficiency numbers of various power systems can be counterintuitive. For example, I've read papers indicating that the most mechanically efficient way to move a ship is oars. Not propellers, paddles, or hydro-jet-thingies. Oars.

The reason people stopped using rowboats except for recreational purposes isn't because they're inefficient. It's because they are very efficiently connected to the most brutally exhausting power supply imaginable: your arms and back muscles. A sail isn't nearly as efficient as converting wind energy into moving-the-boat energy, but it doesn't matter, because you don't have to get out and push the wind. Literally the only reason to build a large vessel powered by oars is if you need to be able to move the ship independent of the wind, and don't have a motor.

Conversely, almost nobody ever seriously tried to build motor-powered boats that used oars... because oars are mechanically much more complicated than just hooking the crankshaft of an engine up to a rotating propeller or set of paddlewheels. You end up with a system that is theoretically efficient, but which breaks down and takes up a lot of unnecessary space and weight on your ship. Not good.

So while the oars are 'efficient' in that they convert the greatest possible fraction of 'moving the oar' energy into 'moving the boat' energy, they lose so hard on other metrics that nobody in their right mind would build a ship to be powered by oars if they had a choice.

[aerius]

We know how much fuel and carbon emissions are associated with generating a kilowatt-hour of electricity. We know how far an electric car can drive on that kilowatt-hour. We know how many gallons of gasoline it would take to cover the same distance, and how much carbon emission is associated with that.

That's all we need to know. Numbers like raw percentage efficiency of one kind of engine versus another are at best irrelevant and at worst actively misleading.

Electricity doesn't get itself from the power plant to inside the battery with 100% efficiency so you can't do a direct kW-h to gallons of gasoline conversion. There are losses in transmission over the grid, losses in AC to DC conversion, and charging losses when you're putting the energy into the battery. These must all be accounted for when calculating how much juice needs to be generated at the power plant, and only then can you figure out how much fuel & carbon emissions you get at the generating station.

[Patroklos]

The same is true of the gasoline though. it doesn't spontaneously convert itself from crude. Nor does it materialize randomly into your gas tank.

[Simon_Jester]

We know how much fuel and carbon emissions are associated with generating a kilowatt-hour of electricity. We know how far an electric car can drive on that kilowatt-hour. We know how many gallons of gasoline it would take to cover the same distance, and how much carbon emission is associated with that.

That's all we need to know. Numbers like raw percentage efficiency of one kind of engine versus another are at best irrelevant and at worst actively misleading.

Electricity doesn't get itself from the power plant to inside the battery with 100% efficiency so you can't do a direct kW-h to gallons of gasoline conversion. There are losses in transmission over the grid, losses in AC to DC conversion, and charging losses when you're putting the energy into the battery. These must all be accounted for when calculating how much juice needs to be generated at the power plant, and only then can you figure out how much fuel & carbon emissions you get at the generating station.

The point remains that certain numbers are relevant, and certain numbers are not. The key numbers are "how much electricity (or fuel) is required to put a kilowatt-hour (or liter of gas) into my car, how much emissions does it cost to do so, and how much performance can I get out of that kilowatt-hour (or liter)."

Theoretical numbers about engine performance are totally beside the point unless they are required to compute one of the above numbers.

[Sea Skimmer]

At the time "Eco boost" engine's became the norm for cars I found out that the combustion efficiency of a turbo charged piston engine was up to 60 percent with naturally aspirated piston engines getting up to 30 percent. What I ponder is what is the combustion efficiency of turbine engine's such as those used in power plants. Axial flow turbines are God in aviation but that has a lot to do with it's power to weight ratio and it being in general a very arodynamicaly clean package I suspect.

No piston engine in a car or truck is anywhere near 60% efficiency. You could only even dream of something like that with a gigantic low RPM turbo diesel on a ship or power plant, and even then that's unlikely to be realized in actual service, though 50% can be. Meanwhile a good modern gas turbine combine cycle plant running on natural gas really can produce 58-59% efficiency to the grid, and they were over 50% a long time ago. Grid transmission losses vary, a few percent to as much as a ten percent depending on the details. Tesla electric cars have about 80% charging efficiency off grid power, higher numbers are plausible for near future batteries, obviously with a superconductor this could become 100% from generator to battery.

Gas and diesel cars and light trucks normally have 35-40% efficiency, but only when they are actually moving at a decent speed. All engine idle time is basically 0% efficiency, and that turns into a lot of engine hours in a country the size of the US, never mind the 4 billion motor vehicles in the world right now. The power plant meanwhile just always operates at its highly efficiency rating, the power industry load balancing means they'll just shed whole generators from the grid rather then run units at poor RPM ranges. Because of that the power grid + electric will just crush conventional cars and trucks at efficiency no matter how you want to slice the numbers. The problems come from all the times efficiency isn't the prime goal, like heavy air conditioner usage, or trucking where the shear mass of the batteries is a problem because the vehicles are already operating at the maximum allowable gross weight. So all battery weight is directly lost payload.

[JI_Joe84]

Thanks, mental note taken. I'd say combustion efficiency will actually drop in the near future because of the 10/11&12 speed transmissions coming online in near future models then.
The battery packs on the Tesla's and other electric car start ups are huge in a physical sense. Tesla's takes up about 4" under the cab from front to back, I shudder to think what Elon Musk has in mind for the Truck he mentioned a couple of times.
Also those batteries take hour's to charge, if some body got that glass electrolyte battery in a car I know they say they are getting twice the power out put of lithium-ion but that's not until heard of there is lithium-magnesium ion and lithium pollimer magnesium that already does that. Kinda funny that none of the electric cars use those batteries.

[Esquire]

The charging time, I note, is a facilities problem and not a logistical one, generally; for the vast majority of users, cars will be idle for hours at a time anyway.

[JI_Joe84]

How is ok you can build a electric car with the range of a conventional car but it's gonna take all night to charge a facility problem and not a technilogical one?
Battery cost and recharge times are the biggest impediments to electric cars taking over from gasoline or diesel. Not charger stations.

[Esquire]

Because the same car, of fossil-fuel powered, would be sitting idle overnight and most of the day besides for all but the most extreme users. It doesn't matter, simply, because nobody drives 300 miles a day or overnight, generally.

[Simon_Jester]

I will note that the range issue IS something that can deter a buyer from going with an electric car.

While I don't actually do a lot of long-distance driving, I have had need to make a trip of roughly 500 miles in a single, specific day on at least one occasion. Waiting a day, or leaving a day earlier, were not options. And this was not 'vacation,' it was need; I'd have lost something rather valuable to me otherwise. There was another time, with slightly lower stakes, that necessitated a round trip of about 200 miles each way. Similar things could easily, foreseeably, arise in my life in the future.

Not everyone gets to keep their entire life neatly compartmentalized within the state line.

I do desire the flexibility that comes from being able to travel hundreds of miles without needing to book transportation that is uncomfortable and may not be available on short notice. Because if I'm in a situation where that's necessary, then bluntly, I have enough trouble without having to add an extra layer of "lol just rent a car they won't mind you driving across state lines" or whatever.

And this is one of the factors in my mind that discourages me from getting an electric car. I could imagine having one gasoline car in a two-car household, but in (for example) the situation that necessitated my long round trip a few years ago, that wouldn't have been a satisfactory alternative. Time was... rather pressing.

[Jub]

I will note that the range issue IS something that can deter a buyer from going with an electric car.

While I don't actually do a lot of long-distance driving, I have had need to make a trip of roughly 500 miles in a single, specific day on at least one occasion. Waiting a day, or leaving a day earlier, were not options. And this was not 'vacation,' it was need; I'd have lost something rather valuable to me otherwise. There was another time, with slightly lower stakes, that necessitated a round trip of about 200 miles each way. Similar things could easily, foreseeably, arise in my life in the future.

That's a pretty rare situation for most people. If you had a car that couldn't make the trip, renting a car or even trading cars with a friend were still options. Without a doubt, these are vastly less convenient options, they're still options though and for most cases they're good enough. I generally wouldn't judge a car on its ability to perform in low odd scenarios.

[Simon_Jester]

Experiences like the ones I describe are certainly 'rare.' Not day-to-day occurrences. Some people may never experience such situations- but some people do. And those people have valid reasons to think in terms of having needs that an electric car can't meet if it needs an overnight recharge to be capable of driving another 300 miles the next day.

One of the things I'm looking for in a car is for that car to be reliably capable of meeting my foreseeable needs. At various times in my recent life, I've had friends and loved ones spread out over a multi-state area, in some cases depending on me for help that I had to be able to travel to provide. Sometimes on fairly short notice. A car that I have to temporarily replace with a friend's (one that may not be available) or a rental (that may not be available on short notice or in the time available) isn't a good option in that situation.

For this reason, I'd cheerfully switch to a hybrid- but not to an electric car, unless they figure out a solution to that problem. And while the people who are in my position may not be a majority of the population, it's at least a relevant thing to consider and take seriously.

Let's not just blithely dismiss the range limitation of current electric cars as being an irrelevant non-issue, okay?

[K. A. Pital]

Because the same car, of fossil-fuel powered, would be sitting idle overnight and most of the day besides for all but the most extreme users. It doesn't matter, simply, because nobody drives 300 miles a day or overnight, generally.

Uh... we do. Also we do it like once a month or once every two months, and we will keep doing it (and we used and will keep using the appropriate car for that, a diesel one). It's just that convenient, good roads, and lots of interesting places within the 400-mile range. And almost any weekend can easily have 150-200 km round trips.

Some people like to travel and like to drive. "Nobody" is taking it too far.

[Elheru Aran]

Example: My parents live ~200 miles away. We go to their house about once every other month or so. That's a 400 mile round trip.

This is absolutely not unusual at all for most Americans.

[houser2112]

300 miles is not very far, only 4 hours at highway speeds. People have the endurance to make trips significantly longer than that. If you have a gasoline car and take a trip that's beyond its range, you can take 10 minutes to fill up on the way to extend it. However, lots of trips become impossible or terribly inconvenient when the range of your car is limited, and the "refill" time is 48x longer. This pretty much forces you to get a room somewhere, which adds to the cost.

[Vain]

I have personally driven my Model S from Baltimore to Atlanta and back again, which is about 700 miles each way. Stops to supercharge made for a relaxed, enjoyable road trip. They take longer than stopping to gas up, but it's nice to get out and decompress for a bit when you're driving that far and I didn't pay a cent for fuel because supercharging is free. Note that I had the option to fly directly there and chose to drive because I thought the road trip would be more fun. Note also that 700 miles is about as much as I can do in one day before I get too tired to safely drive anymore, but I don't think switching to an ICE would dramatically extend my own endurance.

I will concede that there are places where you might want to drive your electric car that don't have fast charging along the route or destination charging at your goal, but that's an infrastructure problem not a technology one.

Finally, in comment threads like this, people always want to come up with scenarios that make a PEV unsuited to their lifestyle. To them I say, fantastic. Don't buy one. Not everyone can afford a Tesla right now, not everyone has a place to charge at home, some people are apparently doing the 24 Hours of Le Mans. If you fall into one of those categories, buy something else. The technology is here, it works for most people, and maybe someday it will work for you. In the meantime, you have other options.

[Elheru Aran]

Being able to stop and take your time while the car charges isn't an issue if you aren't on a timetable. When you have to drive a major distance in a day though you kinda don't want to do that. Take my wife's family reunion... in the far side of Arkansas... when we live in Georgia. It's a 12-hour drive *minimum* for us-- about 800 miles. And we typically make this trip over a weekend. Drive there one day, spend a day there, drive back the next day. Kinda brutal.

EDIT: To elaborate, 800 miles *is* a lot when you have small children in the car, one of the drivers is your mother-in-law who drives like the grandmother she is, and half the distance driven is through the backwoods of Mississippi when you can go a couple hours without seeing a gas station... the only times you really want to stop are for bathroom breaks (ideally when you stop for gas, but with little kids? it's going to be more often than that), gas, and meals.

Which relates to the whole electric-car thing, I guess, by 'refueling'/charging stops taking rather longer than simply gassing up and making the trip take longer than it already is. But again, perhaps that's something that will be changed in the future.

[Vain]

Being able to stop and take your time while the car charges isn't an issue if you aren't on a timetable. When you have to drive a major distance in a day though you kinda don't want to do that. Take my wife's family reunion... in the far side of Arkansas... when we live in Georgia. It's a 12-hour drive *minimum* for us-- about 800 miles. And we typically make this trip over a weekend. Drive there one day, spend a day there, drive back the next day. Kinda brutal.

EDIT: To elaborate, 800 miles *is* a lot when you have small children in the car, one of the drivers is your mother-in-law who drives like the grandmother she is, and half the distance driven is through the backwoods of Mississippi when you can go a couple hours without seeing a gas station... the only times you really want to stop are for bathroom breaks (ideally when you stop for gas, but with little kids? it's going to be more often than that), gas, and meals.

Which relates to the whole electric-car thing, I guess, by 'refueling'/charging stops taking rather longer than simply gassing up and making the trip take longer than it already is. But again, perhaps that's something that will be changed in the future.

That sounds terrible. I have to say, though, I don't think the drive train is your problem in that scenario.

In any case, I absolve you from having to buy an electric car.

[JI_Joe84]

Because the same car, of fossil-fuel powered, would be sitting idle overnight and most of the day besides for all but the most extreme users. It doesn't matter, simply, because nobody drives 300 miles a day or overnight, generally.

A regular car sitting idle has nothing to do with it.
The refuel time is determined by battery chemistry, what it can handle safely and that supper charging situation which you can not rely on normally. That is a technological issue not a logistical one.
Secondly how many miles a person drives in a normal day doesn't matter at all if it falls inside the electric car's range.
Look at this threads topic, you are not even close. Start your own thread.

[Esquire]

I'll freely admit that I over-generalized about people's travel needs and habits. That said...

Because the same car, of fossil-fuel powered, would be sitting idle overnight and most of the day besides for all but the most extreme users. It doesn't matter, simply, because nobody drives 300 miles a day or overnight, generally.

A regular car sitting idle has nothing to do with it.
The refuel time is determined by battery chemistry, what it can handle safely and that supper charging situation which you can not rely on normally. That is a technological issue not a logistical one.

A solved technical issue, unless I'm much mistaken. We can recharge a standard electric-car battery overnight or during the work day, yes? If so, then the issue is availability of charging stations, not inventing them in the first place, and that's logistics.

Secondly how many miles a person drives in a normal day doesn't matter at all if it falls inside the electric car's range. Look at this threads topic, you are not even close. Start your own thread.

That was rather the point. Daily commuting distances do not strain existing electric car ranges, even if you can't recharge it during work, and having to charge the car overnight (or whatever) isn't a problem because your gasoline-powered car would also have been sitting somewhere not being driven about during the same period; it's not wasted time if you have access to a charging station at home or at work. My post was a direct response to yours just above it, too, so you can get off your high horse.

[JI_Joe84]

I'll freely admit that I over-generalized about people's travel needs and habits. That said...

Because the same car, of fossil-fuel powered, would be sitting idle overnight and most of the day besides for all but the most extreme users. It doesn't matter, simply, because nobody drives 300 miles a day or overnight, generally.

A regular car sitting idle has nothing to do with it.
The refuel time is determined by battery chemistry, what it can handle safely and that supper charging situation which you can not rely on normally. That is a technological issue not a logistical one.

A solved technical issue, unless I'm much mistaken. We can recharge a standard electric-car battery overnight or during the work day, yes? If so, then the issue is availability of charging stations, not inventing them in the first place, and that's logistics.

Secondly how many miles a person drives in a normal day doesn't matter at all if it falls inside the electric car's range. Look at this threads topic, you are not even close. Start your own thread.

That was rather the point. Daily commuting distances do not strain existing electric car ranges, even if you can't recharge it during work, and having to charge the car overnight (or whatever) isn't a problem because your gasoline-powered car would also have been sitting somewhere not being driven about during the same period; it's not wasted time if you have access to a charging station at home or at work. My post was a direct response to yours just above it, too, so you can get off your high horse.

I would not call a 6 to 8 hour charge time a solved issue. A charge time equivalent to refueling a conventional vehicle is the goal and arguably one of the things needed to make PEV's the standard conventional drive train.
Charging stations are being built all the time and unless I am mistaken they are along the major routes already. It's the areas off the beaten path that are slower to adopt but they are showing up. I saw one at the local Wal-Mart the other day for example. So not really a problem. Cutting charge time and battery cost to at least the equivalent of gasoline (Petrol for you Brits) would make PEV's as cheap as regular cars and there for more prevalent and there for charging stations that will actually be used.
Installing a charging station is not nearly as hard as a gasoline fueling station. It's just electricity, Petrol has so many environmental concern's that drive up the cost and necessitate big corporations to run. Charging stations are just a pole in the ground, even Wal-Mart can figure that out.
Building charging stations is not the hold up, transitioning to same thing like this glass electrolyte battery using sodium instead of lithium is what will truly unleash electric car's and you will be hard pressed to find any reason to choose gasoline over electricity.
That battery I mentioned the article stated it would take about 10 minutes to charge and had 2 times the energy density of a regular lithium-ion battery.
So that would take these 200 mile range EV's to 400 miles and a turn around time of about 10 minutes. If that works with Sodium Ion then the cost I think will be there.
Then you could sell electric car's right next to hybrid's and regular car's.
As for the original debate, wouldn't a charge time of around 10 minute's totally put to rest all this " but aren't gasoline car's more efficient" non sense??

[Esquire]

I haven't seen any charging stations outside major metropolitan areas, though I confess I wouldn't have been looking for them - I drive a Prius, not a Tesla. Anyway, unless you've got better data than I do, charge time is not the problem. If it takes six to eight hours to charge an existing electric car, as seems plausible, and on any given day any given electric car would be sitting still for eight to ten hours (because leisure time > sleep time) regardless, the only challenge is making sure that electric cars spend their downtime plugged in. It's not wrong to say that the major barrier to cross-country use of electric cars is charging time, but that's a) a small percentage of most people's driving, and b) easily addressed through other means, from gas-powered cars to trains or planes or what-have-you.

I do note, per your last sentence, that begging the question is a formal logical fallacy.

[JI_Joe84]

I agree the lack of charging stations would be a serious draw back to going electric but the first generation had less than 100 miles range and no fast charging capability at all. And they sold just fine.
Maybe it's charging stations and maybe it's battery thechnology. I still see electric cars are way more expensive than traditional gasoline fuelled vehicles.
If a car is going to cost 10k more than other car's it needs a good reason or people won't buy it. That's a fact. That's why I was talking about those new better battery design's. They could allow battery electric cars to get in the price range of conventional cars, then we will see many more electric cars on the roads.
That's my thought, I don't own a electric car yet. Still way to expensive for me but one day I will.

[Borgholio]

It seems to me that the big recurring scenario in this thread is the long-distance road trip where time is of the essence. Long charge times don't really matter if you charge at home while you sleep, or at work, but on the road it can be a very big concern. Before I put a deposit down on my Tesla Model 3, I had to look into the long distance road trip idea...since I did plan on doing such a thing once in awhile. The Superchargers are able to charge a battery to 80% in about half an hour or so. That gives between 2 - 4 hours of driving range depending on factors such as speed, weather, battery size, etc... So while I suppose it's a matter of personal preference, I really don't consider it an inconvenience to take a rest stop for half an hour after every 3 hours of driving on average. Looking at the long trips I plan on taking, I'd actually rather take an EV than a gas vehicle. Some examples:

Palmdale to Mammoth Lakes - one stop in Lone Pine to recharge for half an hour. We usually stop to eat there anyways so we just charge while we eat.

Palmdale to San Francisco - one stop near Fresno to recharge for about half an hour. If we have the bottom of the line battery with only 215 miles of range, then that might be two stops, one in Bakersfield and one in San Jose. Each stop will be about half an hour.

Palmdale to Las Vegas - two stops, one in Barstow and one in Stateline (Primm). These can be shorter than normal stops just due to the placement along the route, so 20 minutes in Barstow and 20 in Primm. With a bigger battery, the Barstow stop can be eliminated.

So basically I'd say that, at least as far as Tesla goes, the charging infrastructure is already there for most destinations. And the amount of extra time on a trip that takes 5 or 6 hours? No more than one extra hour. If you stop to eat and use the restroom along the way, the time it takes you to refill (or purge) yourself can be used to top up. While new battery designs can shave off recharge time and increase range, I'd say that it's already to the point where you don't really need a gasoline vehicle unless you're pretty far off the major routes or it's an emergency where every minute counts.